The FATWO Research Library.

A German team describes one woman whose FATWO came back several times despite surgery and chemotherapy, and how detailed gene testing of her tumour pointed to a targeted medicine that was started too late to judge whether it helped.

The patient or patients

One woman in her early sixties (61), treated in Germany. She had a swollen tummy and lower tummy pain for a few weeks. Scans showed a 15 cm mostly fluid-filled mass coming from the right ovary area. The paper also reviews 16 earlier published women whose FATWO came back and who were treated for it (aged 14 to 75).

What doctors did

First, an operation removed the womb, both ovaries and tubes, the appendix and part of the omentum (a fatty apron inside the tummy). The tumour was fully removed and was confined to the ovary, so no further treatment was advised and she had regular check-up scans. When it came back 8 months later, surgeons removed all visible tumour again. She then had 6 rounds of carboplatin and paclitaxel chemotherapy, followed by 12 rounds of bevacizumab (a drug that cuts off a tumour's blood supply) as 'maintenance' to try to keep it away. When it came back a second time, surgeons removed tumour from the pelvis, part of the liver, part of the small bowel, part of the bladder and some lymph glands. A sample of the liver tumour was sent for very detailed testing (whole-genome and other 'multi-omics' tests) through a German research programme called MASTER. A team of experts (a molecular tumour board) looked at the results. They found changes in two genes, KRAS and MAP2K1, that switch on a growth signal called the MAPK pathway. They recommended a MEK inhibitor tablet called binimetinib, which blocks that signal. Her health insurer at first refused to pay, so meanwhile she had 6 rounds of pegylated liposomal doxorubicin (Caelyx) and then 2 rounds of gemcitabine. The insurer later agreed, and binimetinib was started.

What happened

The tumour came back three times. The first return was 8 months after the first operation. The second was about 25 months after the first diagnosis, while she was still on bevacizumab, and this time it had also spread to lymph glands and the liver. After Caelyx, scans showed the tumour was growing again, with a large mass at the back of the tummy and new spots in the liver. By the time binimetinib could be started, she was very unwell because of how much the tumour had grown, and she had only one dose. The authors say clearly that they cannot tell from this case whether binimetinib works for FATWO. Side effects noted: diarrhoea then constipation with the first chemotherapy, high blood pressure needing treatment with bevacizumab, and a facial rash with Caelyx. This paper also reports survival figures, which we have left out of this summary. This is a single case, so it can't tell us what will happen to others.

Why it matters

This is the first published report of a FATWO that came back being tested in such depth within a structured precision-medicine programme, and it shows that detailed gene testing can find possible targets for medicines even when there is no standard treatment. It also shows the practical problems, such as delays in getting a drug approved and paid for. For researchers, it reports KRAS and MAP2K1 changes, adding to the short list of gene changes described in FATWO, and the authors' review table gathers 17 treated recurrences in one place.

Checked line by line against the paper: 26 Oct 2026.

Doctors in Hangzhou, China, describe the ultrasound scan appearance of four confirmed FATWOs, all of which were misdiagnosed as other conditions before surgery.

Written from the abstract only (full paper not free).

The patient or patients

Four women whose tumours were confirmed as FATWO after surgery, looked back on (retrospectively) at a women's hospital in Hangzhou, China. The abstract does not give their ages or symptoms. The paper also reviews earlier published reports.

What doctors did

The team reviewed the ultrasound scans taken before surgery and compared them with the final pathology. The tumours were examined under the microscope and stained to confirm the diagnosis.

What happened

All four tumours were in the adnexal area (beside the womb) and outside the ovary. Two were solid, darker-looking (hypoechoic) lumps with clear edges and blood flow inside. One was a mixed fluid-and-solid lump with internal walls (septations) and a little blood flow. One was a small fluid-filled, darker-looking lesion. Before surgery, the scans had been read as other things: a fibroma, a corpus luteum cyst or endometrioma, a granulosa cell tumour, and a fibroid (uterine leiomyoma). Under the microscope all four showed the typical FATWO pattern of tubes, cysts and a net-like (reticular) structure. Stains were positive for CK, inhibin, WT-1 and calretinin, and negative for GATA-3 and PAX8. None of the four showed signs of disease during follow-up of 16 to 83 months.

Why it matters

There are few systematic descriptions of how FATWO looks on ultrasound. The authors conclude that FATWO usually appears as a well-defined solid or mixed lump outside the ovary with mild to moderate blood flow, and that when scans show these features, FATWO should be on the list of possible diagnoses, to reduce misdiagnosis before surgery. These are only four cases.

Checked line by line against the paper: 26 Oct 2026.

Korean radiologists describe one woman whose FATWO sat inside her right fallopian tube and contained bone and fatty marrow, which made scans suggest a cancer of the tube, before surgery showed it was a Wolffian tumour.

The patient or patients

One woman aged 61, treated at a hospital in Korea. A scan at a local clinic had found a mass on the right side, near the ovary, with some fluid in the pelvis. She had already had her womb removed in 2012 for fibroids. Her physical examination was normal, and her blood tests, including the CA-125 marker, were normal.

What doctors did

She had an internal ultrasound scan, a CT scan, an MRI scan and a PET-CT scan. These showed a mixed solid and fluid-filled mass of about 6 to 7.5 cm on the right side; the MRI showed it sat inside a swollen right fallopian tube. It had chalky (calcified) areas around its edge and a tiny spot that looked like fat. Some solid parts of it looked 'busy' on the MRI and took up a moderate amount of sugar tracer on the PET-CT, which can be signs of cancer. No spread to lymph glands or elsewhere was seen. Before surgery, the doctors' main thought was a cancer starting in the fallopian tube. Because of the chalky areas and fat, they also wondered about a teratoma (a tumour that can contain different tissue types) that had turned cancerous. She had an operation to remove both fallopian tubes and both ovaries. A 9 cm right-sided mass was found. Fluid washings from the tummy showed no cancer cells. Inside the opened tube, the tumour was attached to the tube wall. Under the microscope, the cells looked bland, with very few dividing cells. There was bone with fatty marrow at the edge of the tumour. Stains were positive for CD10, cytokeratin 7 and pancytokeratin, and negative for PAX8 and GATA3. The final diagnosis was a Wolffian tumour with bone formation.

What happened

She had no further treatment after surgery, such as hormone therapy or chemotherapy. A CT scan seven months after surgery showed no sign of the tumour coming back in the same area. The authors say this is the first reported Wolffian tumour seen as a mass inside the fallopian tube, and the first showing bone with fatty marrow on scans. The usual dark rim seen on some MRI scans of Wolffian tumours was not seen here. From earlier papers, the authors note that about 10 to 20% of these tumours behave aggressively, and they mention advice from the literature of check-ups every 6 months for two years and then once a year. This is a single case, so it can't tell us what will happen to others.

Why it matters

It shows that a FATWO can look like a cancer on scans, including showing up on PET-CT and MRI diffusion scans. The authors suggest doctors should think of a Wolffian tumour when a mass beside the ovary looks worrying on scans but CA-125 is normal.

Checked line by line against the paper: 26 Oct 2026.

A team in Singapore describes one woman whose Wolffian tumour was fully removed, came back 22 months later spread across the lining of her tummy in a more aggressive form, and did not respond well to chemotherapy, which she also found very hard to tolerate.

The patient or patients

One Malay woman aged 68, treated at KK Women's and Children's Hospital in Singapore. She had bleeding after the menopause in December 2021. She had earlier had breast cancer, which was in complete remission. An ultrasound scan showed a suspicious mass by her left tube and ovary. Her CA-125 blood test was 12.8 U/mL at diagnosis.

What doctors did

A scrape of the womb lining (dilatation and curettage) showed only a harmless polyp. In May 2022 she had keyhole surgery to remove the womb, both tubes and ovaries, lymph nodes in the pelvis and along the main blood vessels, and part of the omentum. Surgeons found a 5 cm part-solid, part-fluid mass beside the left ovary, stuck to the bowel and bladder. Everything visible was removed and there was no fluid or spread in the tummy. A quick test during the operation first suggested a different tumour (a granulosa cell tumour). The final lab report, based on the look of the cells and a panel of stains, favoured a Wolffian tumour, likely malignant. The tumour sat in the soft tissue beside the left ovary and involved the fringed end of the tube (the fimbria) and the outer surfaces, but only lay against the ovary and did not clearly involve it. After a team discussion, and because everything had been removed and there was no evidence that extra treatment helps, she chose regular check-ups (active surveillance) rather than chemotherapy. When the tumour came back, surgeons carried out a second operation in April 2024 to remove all visible tumour, leaving no visible disease. Chemotherapy with carboplatin and paclitaxel started in June 2024. She had a severe allergic reaction (anaphylactic shock) to paclitaxel, reduced blood supply to the heart muscle (myocardial ischaemia) and a sudden build-up of acid in the blood (acute lactic acidosis). She then had carboplatin with nab-paclitaxel (Abraxane), but this caused a very low white blood cell count (grade 4) and stomach and bowel side effects, and she became much weaker. Fluid around the lungs had to be drained several times. With the tumour growing and chemotherapy not tolerated, she and her family chose supportive care with the palliative care team.

What happened

She stayed clear for 22 months after the first operation, with steady blood tests and a clear scan in December 2023. About three months later, in March 2024, fluid containing cancer cells built up in her tummy. Her CA-125 had risen to 1,178 U/mL, and another blood marker, beta-hCG, was 4,123 IU/L. Scans showed widespread disease on the lining of the tummy and a thick layer of tumour on the omentum. Under the microscope the returning tumour looked more abnormal and higher grade than the first one (the authors call this anaplastic or malignant transformation), but some areas still looked like the original tumour. Some of the stain results had changed too. Between June and November 2024 the disease grew quickly despite treatment, with fluid around the lungs and enlarged lymph nodes in the back of the tummy, above the collarbone and near the heart, plus new deposits in the tummy and on the lining of the lungs. CA-125 fell to 150.4 U/mL after the second chemotherapy combination, but the authors describe the chemotherapy as poorly tolerated and ineffective. This paper also reports survival figures, which we have left out of this summary. This is a single case, so it can't tell us what will happen to others.

Why it matters

It shows that a Wolffian tumour that looks localised and is fully removed can still come back after a long clear spell, and can return in a more aggressive form. The authors note that the returning tumour had an abnormal p53 pattern, which is unusual for Wolffian tumours, and they think this may be part of the change to a higher-grade tumour. They suggest that gene testing of both the first and the returning tumour would be useful in future cases, and that routine gene testing may be considered for malignant Wolffian tumours. They say there is no agreed approach to follow-up or to drug treatment once the disease has spread, that carboplatin and paclitaxel (borrowed from ovarian cancer care) is the combination most often used but responses vary and side effects are common, and that decisions should be made individually by a team of specialists. They also stress early involvement of palliative care and clear communication. The paper says fewer than 130 cases have been reported worldwide since the 1970s, and that about 10 to 20% may behave aggressively. No gene tests were reported for this patient's tumour.

Checked line by line against the paper: 26 Oct 2026.

Doctors in Belarus describe a 57-year-old woman with a large FATWO of the right ovary and tumour deposits elsewhere in the tummy, all removed in one operation.

Written from the abstract only (full paper not free).

The patient or patients

One woman aged 57, treated at the national cancer centre in Minsk, Belarus. An ultrasound scan of her tummy showed a large tumour of the right ovary.

What doctors did

During the operation, surgeons checked the whole tummy and pelvis. As well as the ovarian tumour, they found tumour deposits on the lining of the tummy (parietal peritoneum), on the mesentery of the sigmoid colon, in the omentum, and in the fatty tissue of the front tummy wall. They carried out radical surgery, removing all of these deposits. The tumour was examined under the microscope and with stains.

What happened

Under the microscope, the tumour's structure and cells did not look like a high-grade (fast-growing) cancer. Taking the stain results and how the illness had behaved into account, the diagnosis was FATWO. The abstract does not describe what happened after surgery. This is a single case, so it can't tell us what will happen to others.

Why it matters

This case shows that a FATWO which did not look high-grade under the microscope had nevertheless spread to several places in the tummy by the time of surgery. The authors stress that FATWO is hard to diagnose because it is rare, its genes vary from case to case, and the available stains are only relatively specific: they mainly help to rule out more common tumours that look similar. The abstract states that about 100 cases have been recorded worldwide since FATWO was first described in 1973.

Checked line by line against the paper: 26 Oct 2026.

This 2026 review compares reported benign and malignant FATWOs with similar tumours that carry STK11 gene changes, and suggests many cases reported as malignant FATWO were probably misdiagnosed.

Written from the abstract only (full paper not free).

The patient or patients

Published cases of FATWO and of adnexal tumours with STK11 gene changes. The number of cases is not given in the abstract.

What doctors did

The authors gathered reported FATWO cases and STK11 adnexal tumours and compared their clinical and microscope features, and discussed which other tumours they can be confused with.

What happened

The abstract says it is not clearly defined in the literature whether FATWOs are benign or malignant, and that, in the authors' view, many of the malignant cases are probably misdiagnoses. It says that finding similar tumours with STK11 gene changes has opened new ways to understand these tumours. The detailed findings are not in the abstract.

Why it matters

It suggests that some tumours called 'malignant FATWO' in the past may really be a different tumour, which matters for how doctors interpret older case reports. The authors say that finding similar tumours with STK11 gene changes has opened new ways to understand these tumours.

Checked line by line against the paper: 26 Oct 2026.

A Portuguese team describes a woman whose 4 cm FATWO beside the left ovary was found by chance on a CT scan, looked like a fibroid on ultrasound and MRI, and was removed by keyhole surgery followed by removal of the womb, ovaries and tubes.

The patient or patients

One woman aged 58, treated in Braga, Portugal. She had had two children. A mass in her pelvis was found by chance on a CT scan done for an inflamed gallbladder. She had no notable medical or family history, including of ovarian or breast cancer. Her examination and blood tests, including tumour markers, were normal.

What doctors did

An internal ultrasound showed a solid, slightly lobed mass of 36 x 28 x 35 mm next to the left ovary, which moved separately from the ovary. It had a mixed pattern with bright spots and shadows, and a moderate blood supply around its edge. Doctors first thought it was a fibroid of the broad ligament. Because it looked unusual, she had an MRI, which confirmed a 36 mm solid mass with no sign of spread. On MRI, the outer solid part looked 'busy' on diffusion imaging (tightly packed cells) and lit up evenly with dye, while the centre looked scarred and did not light up. She chose surgery. Keyhole surgery found a 40 x 40 mm solid mass in the left mesosalpinx, between the ovary and the tube, partly attached to the tube. The womb, tubes and ovaries looked normal and there was no fluid. The mass was removed in a bag; she went home the same day. In the lab, the lump (50 x 35 x 20 mm) showed mainly tube-like patterns, with some solid, net-like and sieve-like areas. Stains: diffusely positive for pancytokeratin (AE1/AE3), calretinin and WT1; patchy positive for alpha-inhibin; focally positive for CD10; negative for EMA, CK7, CD99, chromogranin, synaptophysin, GATA3 and PAX8. This supported a Wolffian tumour of the broad ligament. She was referred to the gynaecological cancer team and, considering the available information, had open surgery to remove the womb and both ovaries and tubes. No other lesions were found in the pelvis or tummy.

What happened

Recovery went smoothly and she went home on the fourth day after the second operation. At her check-up after surgery she was well and had fully recovered. The paper does not report longer-term follow-up. This is a single case, so it can't tell us what will happen to others.

Why it matters

There are few descriptions of what FATWO looks like on ultrasound. This case shows it can cast shadows on ultrasound and look like a fibroid, which makes it hard to tell apart before surgery. The authors note that CD10 positive with PAX8 negative is described as the most reliable stain combination, and that this tumour was unusually CK7 negative. They say the best length of follow-up has not been defined.

Checked line by line against the paper: 26 Oct 2026.

Doctors describe a 64-year-old woman with a FATWO that had spread, who had surgery and six cycles of platinum-based chemotherapy.

Written from the abstract only (full paper not free).

The patient or patients

One woman aged 64 with tummy pain and vomiting for 4 to 5 days. She had had her womb removed about 20 years earlier for abnormal bleeding. Imaging showed an 8 x 7 cm mass in the right adnexa (the area beside the womb where the ovary and tube lie). Tumour blood markers were normal.

What doctors did

Surgeons planned a staging operation with a quick check of the tissue during surgery (frozen section). The frozen section reported an ovarian cancer, so complete staging surgery was done. Because the lab diagnosis was inconclusive, the slides were reviewed by another pathologist, whose stains supported FATWO. As the tumour had spread, a specialist tumour board decided on platinum-based chemotherapy after surgery, and she completed 6 cycles.

What happened

The abstract says the woman is 'disease free till date'. It does not say how long she has been followed. The authors say FATWO is mostly diagnosed by ruling out other more common tumour types, and call for more research into molecular profiling to help predict outcome. They note that around 25 malignant cases had been reported. This is a single case, so it can't tell us what will happen to others.

Why it matters

It adds a case of FATWO that had spread and was treated with platinum chemotherapy after surgery, with no sign of disease reported at the time of writing.

Checked line by line against the paper: 26 Oct 2026.

A cancer centre in Belarus describes a 57-year-old woman with a large FATWO and many tumour deposits in the pelvis and tummy lining, all removed in one operation, and explains how stains confirmed the diagnosis.

The patient or patients

One woman aged 57, three years past the menopause, non-smoker. She had no symptoms; the mass was found during a routine check. Earlier operations: thyroid surgery, appendix removal and removal of fibroids (2014). Scans showed a cystic and solid mass of about 10 x 12 x 7 cm, not attached to the ovaries, and many small deposits up to 15 mm along the womb's ligaments, the pelvic lining and lower tummy. Blood markers (CA-125, HE4, AFP, beta-hCG) were normal.

What doctors did

Surgeons removed the womb, both tubes and ovaries, the lining of the pelvis (peritonectomy), the omentum, and deposits on the bowel mesentery and the front tummy wall. A 12 x 10 x 7 cm mass extending behind the tummy lining was found in front of the womb and bladder, plus nodules up to about 3-4 cm. All visible tumour was removed (complete cytoreduction). Under the microscope the tumour had tube-like, cord-like and solid areas, very little cell abnormality, no dividing cells seen and a Ki-67 below 1%. Stains: positive for vimentin, pancytokeratin and WT1; weak patches of alpha-inhibin and calretinin; patches of progesterone receptor; negative for PAX8, CK7, CK20, ER, CD10, CD117, EMA and others. The deposits in the tummy lining, mesentery, omentum and tummy wall looked the same as the main tumour. Lymph nodes had no cancer. No gene testing is reported.

What happened

The paper describes only the operation. It does not report any further treatment, follow-up length or whether the tumour came back. The authors say the effect of radiotherapy, chemotherapy, hormone and targeted treatments in malignant FATWO remains uncertain, that radical surgery is the mainstay of treatment, and they strongly recommend long-term follow-up for all patients, whatever the first microscope findings. This is a single case, so it can't tell us what will happen to others.

Why it matters

It shows FATWO can be found by chance and can already have spread across the pelvis and tummy at diagnosis, even when it looks very bland under the microscope. It also lists the stains this team used to reach the diagnosis, which matters because there is no single stain that proves FATWO.

Checked line by line against the paper: 26 Oct 2026.

Chinese doctors describe a 53-year-old woman with a small FATWO that was removed by surgery, with gene testing showing a CTNNB1 change and no sign of it coming back after two years.

The patient or patients

One woman aged 53, treated in China (the authors are at Sichuan University). She had gone to hospital for a prolapsed womb and had no symptoms from the tumour; a 2.8 cm round lump beside the womb was found by chance on a CT scan.

What doctors did

Her local hospital removed the tumour, the womb and both ovaries and tubes. The tissue was sent to the authors to be checked. Under the microscope the cells looked mild but were dividing quite often. Stains and gene tests were used to rule out tumours that look similar. A large gene panel (testing 1,021 genes) found one change in a gene called CTNNB1. No extra treatment was given after surgery. She had a CT scan once a year.

What happened

There was no sign of the tumour coming back or spreading at two years after the operation. This is a single case, so it can't tell us what will happen to others. In their review the authors note that FATWO has come back anywhere from 1.5 to 84 months after diagnosis, that it has come back even when the cells were dividing slowly, and that chemotherapy, radiotherapy, hormone and targeted treatments have been used when it comes back but how well they work is not agreed.

Why it matters

It adds one more FATWO to the very small number that have had large gene panel testing (the authors say it is the fourth such study). The CTNNB1 change matches one found in an earlier report, which may help researchers understand how some of these tumours grow. In this one woman, the tumour had not come back two years after full removal even though its cells were dividing quite often; the authors advise long-term scan follow-up when a tumour has worrying features.

Checked line by line against the paper: 26 Oct 2026.

Pathologists describe a 65-year-old woman whose FATWO deposits in the tummy lining were found by chance on a routine scan, and traced back to a cyst operation more than 30 years earlier in which the cyst had been punctured.

Written from the abstract only (full paper not free).

The patient or patients

One woman aged 65. Lumps on the lining of her tummy (peritoneal lesions) were found by chance on a routine ultrasound. The authors are from the University of Chicago (USA) and St Olav's Hospital, Trondheim (Norway).

What doctors did

The lumps were examined under the microscope and with stains, which showed they were FATWO. The team then looked back through her medical records and found that more than 30 years earlier she had had a para-ovarian cyst removed (cystectomy), and the cyst had been punctured during that operation. A review of the slides confirmed the diagnosis of FATWO.

What happened

The authors suggest the tumour cells were spread inside the tummy by the original operation (iatrogenic dissemination), and grew very slowly over three decades. The lesions did not show atypical (worrying) features under the microscope. This is a single case, so it can't tell us what will happen to others.

Why it matters

It shows that FATWO can turn up again a very long time after first surgery, and that spillage of a FATWO during an operation may be one way it ends up in other places. The authors highlight the value of checking a patient's full medical history when a distinctive tumour appears in an unusual place. They say that the slow growth and lack of atypical features in this case support the idea that most FATWOs are benign.

Checked line by line against the paper: 26 Oct 2026.

A Chinese team describes a woman with no symptoms whose 5.2 cm FATWO inside the left ovary was found at a routine check and removed, and reviews 11 other FATWO cases reported over the past ten years.

The patient or patients

One woman aged 54, past the menopause, treated in China in 2024. She had no symptoms: no tummy pain, no unusual bleeding and no bladder or bowel problems. A firm, movable, non-tender lump of about 5 cm was felt on the left side during a routine examination. The paper also has a table of 11 earlier published cases (aged 34 to 75).

What doctors did

An internal ultrasound showed a 5.2 cm solid lump on the left side with some blood flow. A CT scan showed a solid mass, most likely from the ovary, with no swollen lymph glands. Blood tumour markers were normal (CA-125 16.7 U/ml, AFP and CEA also normal). Before surgery the doctors thought it was most likely harmless, such as a fibroma or a fibroid. She had keyhole surgery through a single cut at the belly button. A 5 x 4 x 4 cm solid lump was found inside the left ovary, with no fluid or spots elsewhere in the tummy. A quick test on the tissue during the operation (frozen section) suggested FATWO. After discussion with her relatives during the operation, the womb, both ovaries and both tubes were removed. The final lab report confirmed a Wolffian tumour of 5.2 cm, contained within the ovary, with clear edges. The cells looked uniform and bland. Stains: FOXL2 strongly positive; calretinin, SF-1, alpha-inhibin and vimentin positive; CD10 focally positive; AR positive; ER, PR, EMA, GATA3 and TTF-1 negative. Ki-67 was about 1%, meaning very few cells were dividing. A team of specialists advised no further treatment, but close check-ups every three months with examination, blood markers and scans.

What happened

She recovered well and went home 4 days after surgery. At 12 months she had no symptoms, normal blood markers, and no sign of the tumour coming back on ultrasound or CT. Check-ups are continuing. In their review, the authors note that several earlier cases came back after surgery, and that chemotherapy has had mixed and often short-lived results; they say carboplatin with paclitaxel currently has the most support for tumours that come back or spread. They also note that imatinib (a targeted drug) only held one tumour steady for a short time. This paper also reports survival figures, which we have left out of this summary. This is a single case, so it can't tell us what will happen to others.

Why it matters

It shows a FATWO can be found by chance in a woman with no symptoms and normal blood tests. The authors argue that FATWO should not be thought of as always harmless, advise removing the womb, ovaries and tubes for women past the menopause, and say treatment after surgery should be decided case by case by a specialist team. They point out there is little evidence to guide care for younger women who want to keep their fertility. The authors also mention that tumours with STK11 changes may be a separate type, sometimes called 'STK11 adnexal tumours'; later papers treat these as a separate type.

Checked line by line against the paper: 26 Oct 2026.

A team in Qingdao, China, describes one woman with a large, fast-growing Wolffian tumour beside the left ovary who had full surgery followed by four cycles of chemotherapy and showed no sign of it coming back 9 months after surgery.

The patient or patients

One woman aged 64, treated at the Affiliated Hospital of Qingdao University in China. She had tummy pain and swelling for 8 months. A CT scan showed a well-defined 9.3 x 5.8 cm mass in the left adnexal area, with no enlarged lymph nodes. An ultrasound showed an 8.4 x 7.9 x 6.8 cm mass next to the left ovary, with no clear border between them. Her CA-125 blood test was 38.6 U/mL. Two other blood markers were also measured: HE4 was 83.8 pmol/L and NSE was 30.8 ng/mL.

What doctors did

Surgeons opened the tummy (exploratory laparotomy). They found a small amount of pale-yellow fluid and a 12 x 10 cm solid mass between the left tube and ovary, firmly stuck to the broad ligament and nearby bowel. The left ovary looked normal, and the right side, omentum, liver and spleen showed no visible tumour. A quick test during surgery showed a poorly differentiated malignant tumour with dead tissue, and the possible types included germ cell, sex cord-stromal or a cancer spread from elsewhere. Because the type was unclear and there might be tiny spread to lymph nodes, surgeons removed the womb, both tubes and ovaries, the omentum and the pelvic lymph nodes, and freed the stuck tissue. The final lab report showed an 11 x 7 x 7 cm poorly differentiated malignant tumour with dead tissue, very abnormal-looking cells and many dividing cells. The authors diagnosed a Wolffian adnexal tumour, FIGO stage IC. A gene test found a BRCA1 change described as having established clinical significance, and a TP53 change of possible relevance. She then had four cycles of chemotherapy with paclitaxel and carboplatin (the TC regimen).

What happened

Her tumour markers returned to normal by the second cycle of chemotherapy. At 9 months after surgery, a pelvic CT scan and an ultrasound showed no sign of it coming back or spreading, and her CA-125 kept falling over time. The authors advise long-term follow-up to pick up any return early. This is a single case, so it can't tell us what will happen to others.

Why it matters

Wolffian tumours are usually harmless, so this is a rare example of one described as malignant, with features such as dead tissue, very abnormal cells and frequent cell division. The authors say there is no agreed treatment, and that the role of chemotherapy and radiotherapy is debated. They suggest that gene changes such as BRCA1 and TP53 might one day point to targeted treatments. They mention that PARP inhibitors are used for BRCA-changed ovarian cancer but have not been tested in Wolffian tumours. They also mention an earlier report of a 15-year-old whose tumour responded to imatinib (Gleevec). The paper says fewer than 90 cases had been reported, and quotes earlier work that malignant Wolffian tumours have an estimated recurrence rate of 11%, most often in the lungs and liver. Its stain pattern (ER and PR positive, GATA3 negative) is different from the pattern the authors themselves describe as typical for this tumour (see Points we could not confirm). No STK11 result is reported.

Checked line by line against the paper: 26 Oct 2026.

A short US conference abstract describes a woman whose 20 cm FATWO was removed in 2019 and which came back spread through the omentum in 2024, where an STK11 gene change was found and chemotherapy was started with a targeted medicine planned.

Written from the abstract only (full text could not be opened).

The patient or patients

One woman aged 43, treated at a medical centre in the United States. In 2019 she had an operation planned to remove her womb because of fibroids, and a 20 cm mass was found on the right side, beside the womb.

What doctors did

In 2019, her womb (leaving the cervix) and both ovaries and tubes were removed. Under the microscope the mass was most consistent with a FATWO, with few dividing cells. Stains showed a mix of patterns: diffuse AE1/AE3, ER, calretinin, WT-1 and D2-40; negative CDX2, CD117, OCT3/4, AFP and MOC-31; patchy 'SF-10' (probably SF-1), CK-7, EMA and inhibin A; BAP1 and MTAP retained; p53, p16, Napsin A, chromogranin and synaptophysin not significantly expressed. She did not return for follow-up. In 2024 she came to the hospital with blood clots in a neck vein and in a vein of the left pelvis and leg. A CT scan showed widespread tumour in the omentum. A biopsy of the omentum looked the same as the original FATWO and showed an STK11 gene change. Because of the amount of disease, she was not considered suitable for surgery to remove it. She was started on carboplatin and paclitaxel chemotherapy, and an mTOR inhibitor was planned because of the STK11 change.

What happened

At the time of writing she had just completed her third cycle of chemotherapy, and her response was still being monitored; no result is reported. The authors note that, from earlier reports, FATWO comes back or spreads in about 11% of cases and can do so as early as two years after diagnosis, and that there are no clear recommendations on how best to treat FATWO that has come back or spread. This is a single case, so it can't tell us what will happen to others.

Why it matters

It is an example of a FATWO coming back several years after surgery, and of gene testing pointing towards a targeted medicine (an mTOR inhibitor) because of an STK11 change. The authors call this tumour a FATWO with an STK11 mutation; later papers treat tumours with STK11 changes as a separate type, called STK11 adnexal tumour.

Checked line by line against the paper: 26 Oct 2026.

Pathologists in Mashhad, Iran, describe a 40-year-old woman with an 8 cm FATWO in her right ovary that was first mistaken for other tumour types under the microscope.

Written from the abstract only (full text could not be opened).

The patient or patients

One woman aged 40, in Iran. A mass on her right ovary had been seen by chance on an ultrasound 4 years earlier, but it was not followed up. For 2 months she had needed to pass urine often, and this did not settle with treatment. Ultrasound and MRI showed an 8 cm mass in the right ovary pressing on the bladder.

What doctors did

She had an operation to remove the womb and both ovaries and tubes. The first lab diagnoses were a germ cell tumour and an ovarian carcinoid. On repeated microscope review, the tumour had small cube-shaped to many-sided cells in cord-like, island-like and small follicle-like patterns, with pink secretions in small spaces and 3 dividing cells per 10 high-power fields. The final diagnosis was FATWO.

What happened

She went home after surgery and was advised to have follow-up ultrasound scans. This is a single case, so it can't tell us what will happen to others.

Why it matters

The case shows that FATWO can be mistaken for other tumours under the microscope. The authors say the main look-alikes are granulosa cell tumour, Sertoli-Leydig cell tumour and clear cell carcinoma. They say FATWO should be considered at any age, and because it can become malignant, come back or spread, they say follow-up of patients is essential.

Checked line by line against the paper: 26 Oct 2026.

A pathology study of 21 tumours (18 Wolffian tumours/FATWOs and 3 STK11 adnexal tumours) shows they often take up the same stains as mesothelioma, and in 3 cases mesothelioma was strongly considered or wrongly diagnosed.

Written from the abstract only (full paper not free).

The patient or patients

21 tumours: 18 Wolffian tumours (FATWO) and 3 STK11 adnexal tumours. Patients were aged 25 to 73 (average 51). The tumours were in the adnexa or broad ligament (6), beside the fallopian tube (5), in or beside the ovary (5), inside the tube (2), in the pelvis (2) and in the liver (1). Average size was 9.3 cm (from 0.2 to 22 cm). The authors are from Ottawa (Canada) and from Cleveland Clinic, Mayo Clinic (Arizona) and Stanford University in the USA.

What doctors did

Pathologists reviewed the microscope appearance and stains of each tumour, and did extra stains where tissue was available. They focused on stains normally used to diagnose mesothelioma (calretinin, WT1, D2-40) and on stains usually negative in mesothelioma (claudin-4, MOC31, BER-EP4).

What happened

Most tumours (14 of 21) were made of tubes and solid sheets of uniform cells. At least 7 showed squashed tubes with slit-like spaces and a sieve-like pattern. Three showed the pattern described in STK11 adnexal tumours: joined-up cords of cells growing in a jelly-like (myxoid) background. Of 9 cases tested with all three mesothelial stains, 5 were positive for all three. Of 16 cases tested with at least two, 11 were positive for two (mostly calretinin and WT1). Claudin-4, MOC31 and BER-EP4 were negative in most cases tested. In 3 cases (14%), mesothelioma was strongly considered at first or was actually diagnosed by mistake.

Why it matters

Because Wolffian tumours and STK11 adnexal tumours can look and stain like mesothelioma, especially when they have spread, they can be misdiagnosed. The authors say these tumours should be considered whenever a pelvic or peritoneal mesothelioma is being diagnosed. The authors themselves treat STK11 adnexal tumour as a separate, recently defined relative of Wolffian tumour. They note that most of these tumours have a good outlook, but up to half of STK11 adnexal tumours behave aggressively.

Checked line by line against the paper: 26 Oct 2026.

Doctors in Chandigarh, India, describe a woman in her sixties with two years of lower tummy pain who was found to have an 8 cm solid FATWO beside her right ovary.

Written from the abstract only (full paper not free).

The patient or patients

One woman in her sixties, treated in Chandigarh, India. She had lower tummy pain for 2 years. Her gynaecological history was unremarkable and she had gone through the menopause without problems. On examination, doctors felt a firm, solid lump on the right side beside the womb.

What doctors did

Scans suggested a right-sided adnexal mass of 6 x 9 x 7 cm. She had a staging laparotomy (open operation to remove the tumour and check for spread). During the operation, an 8 x 8 cm solid, fibrous mass was found. Under the microscope the tumour cells showed a focal gyriform (wavy, ribbon-like) pattern and stained positive for calretinin and WT-1, leading to a diagnosis of FATWO.

What happened

She was kept on regular follow-up and no sign of the tumour coming back was seen. The abstract reports on her five years later. This paper also reports survival figures, which we have left out of this summary. This is a single case, so it can't tell us what will happen to others.

Why it matters

The authors describe FATWO as a rare tumour of low malignant potential that is hard to diagnose because its symptoms are vague, it looks different from case to case under the microscope, and its scan features are not well defined. This case adds one more FATWO with no sign of coming back after surgery, as far as the abstract reports.

Checked line by line against the paper: 26 Oct 2026.

A team in Qingdao, China, describes a 33-year-old whose tumour beside the left fallopian tube first looked harmless, came back a year later spread throughout her tummy, and after many changes of treatment shrank on a combination of a targeted tablet (lenvatinib) and a hormone tablet (letrozole).

The patient or patients

One woman aged 33, treated at the Affiliated Hospital of Qingdao University in China. A pelvic mass had been found about two weeks before she came to the hospital in 2021. Her CA-125 blood test was 42.9 U/mL. An ultrasound showed a 7.0 x 7.6 cm part-fluid mass near the upper left of the womb. The paper describes her as never having given birth.

What doctors did

In April 2021 surgeons removed an 8 x 6 cm part-solid, part-fluid tumour from the tissue beside the left fallopian tube by keyhole surgery. Under the microscope the cells looked mild, and the first diagnosis suggested a granulosa cell tumour. After the slides were reviewed by experts at the University of Pittsburgh Medical Center (USA) and Peking University People's Hospital, a Wolffian tumour was considered. The tumour had been fully removed, so she had regular check-ups only. CT and PET-CT scans in the months after surgery were normal. When the tumour came back, surgeons carried out a major operation in May 2022 to remove as much as possible. This removed the womb, both tubes and ovaries, lymph nodes, tumour deposits in the pelvis, the omentum and the appendix, and heated chemotherapy was washed through the tummy during surgery. Some tumour was left behind on microscope checks (R1). A gene test of the tumour found 11 changes, 9 described as clinically significant, including STK11 and TP53. She then had a long series of treatments: nab-paclitaxel and carboplatin with bevacizumab; then a combination including cyclophosphamide and bevacizumab; then docetaxel, nedaplatin and bevacizumab with the hormone tablet anastrozole; then bevacizumab alone; then gemcitabine with bevacizumab; then gemcitabine, oxaliplatin and lenvatinib; and from November 2023, lenvatinib with letrozole tablets.

What happened

About one year after the first operation she developed sudden swelling of the tummy. CT scans showed tumour throughout the pelvis, lymph nodes at the back of the tummy, the lining of the tummy and the omentum, with a possible spread to lymph nodes near the heart. Her CA-125 had risen to 453.9 U/mL. At surgery there were about 4 litres of fluid in the tummy, masses of 12 cm and 8 cm in the areas of both ovaries, a 6 cm mass behind the womb, and many small nodules across the tummy, bowel, liver area, spleen area and diaphragm. Two out of two lymph nodes checked had cancer in them. The tumour now looked more abnormal and was growing faster (Ki-67 40%, up from 20%). The final diagnosis was given as a stage IV malignant tumour of the fallopian tube, described as a Wolffian duct tumour. The first chemotherapy shrank the tumour, but the side effects were too hard to tolerate. On the next combination the tumour grew, with new spread on the lining around the liver, along the lymph node routes beside the breastbone, and in the angle between the heart and diaphragm. The docetaxel, nedaplatin and bevacizumab combination kept it stable, but again the side effects were too severe. During bevacizumab alone it grew again, and in June 2023 she had chest pain from fluid and tumour on the lining of the lungs. Gemcitabine with bevacizumab did not stop it. Gemcitabine, oxaliplatin and lenvatinib shrank it partly, but she stopped because of side effects. On lenvatinib (12 mg daily) with letrozole (2.5 mg daily), the tumour deposits shrank steadily over 7 months and CA-125 and other markers fell to normal. The authors describe this response as unexpected. This paper also reports survival figures, which we have left out of this summary. This is a single case, so it can't tell us what will happen to others.

Why it matters

This is a detailed record of many lines of treatment for a Wolffian tumour that came back and spread, showing which ones the tumour responded to and which it did not. The authors suggest that, for advanced or returning Wolffian tumours, platinum chemotherapy with drugs that block blood vessel growth and hormone therapy looks promising, but they say more follow-up and more cases are needed to confirm this. The tumour stained positive for oestrogen and progesterone receptors, which is why hormone tablets were tried. Its gene test included an STK11 change. Later papers treat tumours with STK11 changes as a separate type, called STK11 adnexal tumour; this paper uses the label Wolffian tumour. The authors say only about one hundred cases had been reported.

Checked line by line against the paper: 26 Oct 2026.

A team in Tehran, Iran, describes a 35-year-old woman whose Wolffian tumour was removed with the left ovary and tube, then appeared in the right tube and ovary two years later, and was treated with further surgery, chemotherapy and radiotherapy, with no further return reported so far.

The patient or patients

One Iranian woman aged 35, who had had one pregnancy and one child. In 2019 an ultrasound found a mass by chance on her left side, about 10 cm across. Her ovarian blood markers (CA-125, CEA and CA19-9) were normal at that time. The paper also includes a table of 27 earlier published cases of FATWO, most of which came back or spread.

What doctors did

First operation (2019): surgeons removed the left ovary and tube and took a sample of the omentum. Under the microscope the tumour had spindle-shaped cells with branching tubes and sieve-like patterns, and few dividing or very abnormal cells. It had grown into the outer surface of the left tube, and the omentum was also involved. Stains were used to rule out look-alike tumours, and the diagnosis was a tumour of probable Wolffian origin. She then had check-ups. Second operation (2021): when a new mass appeared on the right, surgeons removed the right ovarian growth (cystectomy), a mass on the omentum, and an area of deep endometriosis behind the womb. A quick test during surgery suggested a Wolffian tumour, and this was confirmed. Third operation: after an MRI scan scored both sides as high risk (O-RADS 5), she had a full debulking operation, removing the womb, the right tube and ovary, the omentum and lymph nodes. Her specialist team then planned 6 rounds of chemotherapy with paclitaxel and carboplatin, followed by radiotherapy to the pelvis.

What happened

Two years after the first operation (2021), scans showed a multi-chambered fluid-filled growth in the right tube and ovary. CA-125 was 83 at this point (units not given). The right-sided tumour was 6 cm, with moderately abnormal cells, 5 dividing cells per 10 high-power fields, tumour on the surface of the ovary and tumour inside small blood or lymph vessels. The omentum was involved again. The authors diagnosed a bilateral (both sides) adnexal tumour of Wolffian origin with malignant behaviour. After the third operation and the planned chemotherapy and radiotherapy, the authors say she remains under close observation and no recurrences have been detected. They do not say how long she has been followed since the third operation. This paper also reports survival figures, which we have left out of this summary. This is a single case, so it can't tell us what will happen to others.

Why it matters

Tumours of this kind on both sides are described by the authors as extremely rare, and they treat the right-sided tumour as a spread from the left (a sign of malignant behaviour). They point out that most returns in published cases happened in women who first had smaller, conservative operations, as in this case, and that the most successful treatment for a first FATWO is complete removal, including the womb and both tubes and ovaries. They say the effect of chemotherapy, radiotherapy, hormone therapy and targeted drugs on malignant FATWO is unknown, and that paclitaxel with carboplatin is the most often used chemotherapy. They advise regular routine follow-up for all FATWO patients. Their literature table lists times to coming back in published cases ranging from about 1 month to 84 months. The paper mentions STK11 among gene changes reported in FATWOs; later papers treat tumours with STK11 changes as a separate type, STK11 adnexal tumour. No gene tests were done on this patient's tumour.

Checked line by line against the paper: 26 Oct 2026.

A Chinese team describes one woman with a 25 cm Wolffian tumour affecting both ovaries, which first showed up as fluid around her lungs and heart, and which was treated with major surgery and six cycles of chemotherapy, with no return over three years.

The patient or patients

One woman aged 58, treated in Guangdong, China, in 2021. She had vaginal bleeding after the menopause for over a year and a swollen tummy for six months. Two months earlier, another hospital had treated her for a cough and breathlessness caused by fluid around the lung; no tumour cells were found in that fluid. She could not lie flat to sleep. Her legs were swollen. She also had high blood pressure and gout.

What doctors did

Ultrasound showed fluid around the heart and around the right lung. MRI showed a huge mass of 25.3 x 17.8 x 21.9 cm in the lower tummy and pelvis involving both ovaries, thought likely to be a cancer. Blood markers CA-125, CA19-9 and HE4 were raised; hormone levels were normal. She had open surgery. The main mass, about 25 x 25 x 20 cm, came from the left ovary, was stuck to the bowel and had many enlarged blood vessels; it weighed 3.27 kg. A second, 8 x 10 x 10 cm mass was found on the right side. The womb, both ovaries and tubes, and the omentum were removed. There was heavy bleeding during the operation (3,000 mL) and a brief drop in blood pressure, which was brought under control. The lab found a Wolffian tumour in the left ovary and the right tube and ovary; the left tube, omentum and bowel surfaces were not involved. Under the microscope the cells showed moderate abnormality, with fewer than 5 dividing cells per 10 high-power fields. Stains: CK-pan positive, CK7 partly positive, EMA negative, vimentin positive, PAX-8 negative, ER positive in 80% of cells, PR positive in 10%, alpha-inhibin and calretinin negative, Syn focally positive, CD10 positive, GATA3 and TTF-1 negative, CD99 partly positive, p53 negative, WT-1 focally weakly positive. Ki-67 was 20%. The final diagnosis was stage IIA. She then had six cycles of chemotherapy with taxol (paclitaxel) and cisplatin.

What happened

After surgery, CA19-9 and HE4 returned to normal and CA-125 fell; all tumour markers were normal after the six cycles of chemotherapy. Two months after surgery, the fluid around the heart and lung had cleared. There was no sign of the tumour coming back during three years of follow-up. The authors say the cause of the fluid around the heart and lung is unclear. This is a single case, so it can't tell us what will happen to others.

Why it matters

The authors say this is the first report of a giant Wolffian tumour on both sides, and of one first showing up as fluid around the heart and lungs. They describe the MRI appearance in detail. They suggest that, because the tumour was large and stage IIA, chemotherapy as used for ovarian cancer was recommended, and that thorough surgery plus chemotherapy where needed may help reduce the chance of it coming back. This is the authors' view from one case.

Checked line by line against the paper: 26 Oct 2026.

A Chinese team describes the MRI appearance of an 11 to 12 cm Wolffian tumour in the right ovary of a woman with irregular bleeding, and pulls together the MRI findings from nine reported cases.

The patient or patients

One woman aged 56, past the menopause, treated in Jinhua, China. She had a year of irregular, heavy vaginal bleeding with clots. An ultrasound at a local hospital found a mass of about 10.7 x 10.1 cm on the right side, and several lumps in the muscle wall of the womb. She had no tummy pain, fever or bladder symptoms, and no family history of cancer. A hard, well-defined swelling of about 10 cm was felt on the right side. Her tumour markers (CA-125, CA19-9) and other cancer blood tests were normal.

What doctors did

MRI showed a well-defined oval solid mass about 11 cm across on the right side, with a capsule and a fluid-filled dead (necrotic) centre. Its signal on MRI was similar to muscle on one type of picture (T1) and slightly brighter on another (T2). It was very bright on diffusion imaging, meaning tightly packed cells. The capsule showed a clear dark rim on T2 pictures. The solid part lit up moderately and evenly with contrast dye. The right ovary could not be seen separately, so the mass probably came from it. No swollen lymph glands were seen. Before surgery, the doctors thought it was most likely a thecoma (a usually harmless ovarian tumour). At surgery, the right ovary was enlarged to about 12 cm with many blood vessels; the womb was enlarged with a 4 x 3 cm bulge; there was about 50 mL of yellowish fluid in the tummy. Both ovaries and tubes and the womb were removed. A quick test during the operation suggested a possible cancer. Under the microscope, the cells formed slit-like or fern-leaf patterns, with rare dividing cells. Stains: positive for alpha-inhibin, calretinin, CD10, pan cytokeratin, CK19, WT-1, Des, P16, Melan-A and Vim; negative for Pax-8, CK7, EMA, AR, ER and PR. Ki-67 was about 20%. The final diagnosis was a Wolffian tumour from the right ovary.

What happened

No further treatment after surgery was needed. She was followed for 6 months with no sign of the tumour coming back or spreading. In their review of nine cases with MRI (including this one), the authors found that all were very bright on diffusion imaging, six of nine had a dark rim around the edge on T2 pictures, and none showed signs of spread on MRI. This is a single case, so it can't tell us what will happen to others.

Why it matters

Wolffian tumours are hard to diagnose before surgery. The authors suggest the dark rim around the edge on MRI, together with very bright diffusion signal and moderate even enhancement, may help doctors think of a Wolffian tumour before an operation. They also note, from the literature, that tumours of 10 cm or more and those invading nearby structures are more likely to behave like a cancer.

Checked line by line against the paper: 26 Oct 2026.

An Italian team describes a small FATWO found by chance on the ovary and treated by surgery alone, and pulls together 165 published cases, finding that fewer than 1 in 5 came back.

The patient or patients

The new case: one woman aged 52 from Italy, past the menopause, with no symptoms; a cyst on her right ovary was found on a routine scan. The review: 165 cases from 74 published papers (including this one), aged 13 to 83, with a middle (median) age of 50.

What doctors did

For the new case: an ultrasound scan, normal blood tumour markers (including CA-125), then keyhole surgery to remove both ovaries and fallopian tubes, a fluid wash of the abdomen and a sample of the womb lining. After the tumour was confirmed as FATWO, a team of specialists planned a second operation to remove the womb and take samples from the omentum and abdominal lining. All of these were clear. No chemotherapy or radiotherapy was given. In the published cases, surgery was the first treatment where this was reported, most often removal of the womb, both ovaries and tubes; a few women had extra treatment afterwards (platinum chemotherapy in 5, radiotherapy in 2, tamoxifen in 1).

What happened

The woman in the new case had check-ups every 6 months and had no sign of the tumour at the time the paper was published. The new case is a single case, so on its own it can't tell us what will happen to others. Across the review, the tumour came back in 29 of the 165 cases (17.5%, a little under 1 in 5). Where it came back, the commonest places were the abdominal lining (peritoneum), the liver, the broad ligament and the omentum; rarer places included the top of the vagina (vaginal cuff). Among women whose tumour came back, the middle time to it coming back was about two years. A quarter of the women whose tumour came back had first had only the lump removed. Most recurrences (69%) were treated with surgery, sometimes followed by medicines or chemoradiation. The authors say carboplatin with paclitaxel chemotherapy kept the disease stable in some women whose tumour had spread, but treatments varied too much to draw firm conclusions. Four women whose tumour had spread were given tyrosine kinase inhibitors (targeted tablets), and other authors reported a good response in some. This paper also reports survival figures, which we have left out of this summary.

Why it matters

This is one of the largest collections of FATWO cases so far, and it shows that most of these tumours do not come back after surgery, though some do. It gives families a picture of where the tumour tends to be found and where it can come back. The authors ask for every new case to be published and for gene testing (for example for STK11) so that targeted treatments can be studied.

Checked line by line against the paper: 26 Oct 2026.

A Russian team from Tomsk describes a 75-year-old woman whose 7 cm lump beside the womb was thought to be a fibroid until lab tests after her hysterectomy showed it was a FATWO, and reviews how the tumour is diagnosed.

The patient or patients

One woman aged 75, seen at a cancer research institute in Tomsk, Russia, from December 2022. She had long-standing low back pain and some vaginal bleeding after physical effort. She had small procedures in December 2022 and March 2024 to look inside the womb and remove polyps; these were harmless (benign) polyps, with some thickening of the womb lining the second time. In December 2023 her pain got worse and she had spotting. An ultrasound showed a lump on the left edge of the womb, thought to be a fibroid, which had grown from 53 x 32 mm in 2022 to 78 x 66 mm.

What doctors did

Because the polyps kept returning and because of her age, in April 2024 she had keyhole surgery to remove the womb, ovaries and tubes. During the operation there was a 7 cm lump in front of the womb, with scar tissue (adhesions) around it; a fixed lump stuck to the womb filled the tissue at its side. A small amount of fluid was tested and contained only normal lining cells. The lump looked like a fibroid and was separated from the womb, which it was joined to by a thin stalk. In the lab, the lump was made of closely packed gland-like and tube-like structures, some sieve-like, with mildly to moderately varied cells. Dividing cells were few (up to 1 to 2 per 10 high-power fields). Stains: strongly positive for CK7 and CK19; CD10 positive (mainly at the inner edge of the cells); P16 positive in a block pattern; a few cells positive for CA-19-9 and HBME-1; p53 showed the normal ('wild-type') pattern. Negative for PAX8, GATA-3, oestrogen receptor, TTF1, CEA, SATB-2, CDX2, WT1, SOX-2 and GPC3. Calretinin and inhibin alpha were patchily positive in the supporting tissue. Ki-67 was low, under 1%. To rule out a tumour that had spread from somewhere else, she had a pelvic MRI, a CT of the tummy, a mammogram, and camera tests of the stomach and bowel; none showed another tumour. The diagnosis was FATWO. No tumour was found in the cervix, womb or tubes.

What happened

Recovery after surgery was without complications. She was advised to have regular check-ups, and at the time of writing she had been followed for 6 months. The paper does not say whether any scans in that time showed the tumour coming back. This is a single case, so it can't tell us what will happen to others.

Why it matters

It shows how a FATWO beside the womb can be mistaken for a fibroid on ultrasound and at surgery, and that only detailed lab tests and stains gave the right diagnosis. The paper also gives a long review in Russian of how FATWO develops before birth, the stains used, gene findings from earlier studies, and treatment. The authors note a recent review found that many tumours once called malignant FATWO were in fact STK11 adnexal tumours or unusual endometrioid cancers; later papers treat STK11-changed tumours as a separate type.

Checked line by line against the paper: 26 Oct 2026.

A team in Caracas, Venezuela, describes a 56-year-old woman whose tumour was first reported as an ovarian cancer and then as a low-grade sarcoma, before reviews at two international centres settled on FATWO, which meant she was monitored rather than given further treatment.

The patient or patients

One woman aged 56, treated at Centro Médico Docente La Trinidad in Caracas, Venezuela. A mass on the right ovary was found on ultrasound during a gynaecological check-up. It measured 5.5 cm by 4.9 cm on ultrasound. An MRI scan showed a mainly fluid-filled mass of 6 cm by 3.3 cm in the right adnexa, with a swollen right fallopian tube that had a solid part inside it. Her blood tumour markers (CA-125, CEA and CA 15-3) were normal.

What doctors did

On 1 July 2022 she had an open operation to remove the womb and both ovaries. During the operation a quick frozen-section test reported a 'round cell tumour', so the surgeons took fluid washings from the tummy and checked the other organs; they saw no signs of the tumour spreading. The first full lab report called it a poorly differentiated endometrioid cancer of the right ovary growing into the fallopian tube (grade 3), with positive fluid washings. Its stains were: inhibin negative, oestrogen receptor positive in 80% of cells, progesterone receptor positive in 20%, vimentin positive, WT1 and CK7 negative, with 4 to 7 dividing cells per 10 high-power fields and a growth-rate stain (proliferation index) of 8%. She was referred to the cancer medicine team for extra treatment. That team first asked their own pathologists to look again. This second review, with more stains, called it a well-differentiated low-grade sarcoma with no dividing cells seen and no dead tissue. Because the two reports disagreed, the tissue was sent to two international centres and reviewed again in-house. The final diagnosis was FATWO. The stains supporting this were: keratins (pankeratin) positive, androgen receptor positive, oestrogen receptor positive in 99%, progesterone receptor positive in 30%, CD10 and EMA positive, and CK7, CK20, calretinin, SF-1, PAX-8, WT-1, GATA-3 and TTF-1 negative. Because the tumour was described as behaving in a benign way and had been fully removed, and further tests were normal, the doctors chose regular check-ups instead of extra treatment.

What happened

At the time of writing she had had no sign of the tumour coming back for 14 months. This is a single case, so it can't tell us what will happen to others.

Why it matters

This case shows how hard FATWO can be to recognise under the microscope. The same tumour was called two different cancers before experts in other countries agreed it was FATWO. The final diagnosis changed her care: she avoided extra treatment that might have been given for an ovarian cancer or a sarcoma. The authors say surgery to remove the tumour is the main treatment, and that there is no well-established evidence for extra treatments because the condition is so rare. In their discussion they note that carboplatin and paclitaxel is the chemotherapy most used in malignant cases reported elsewhere, and that imatinib has been tried in some tumours that stain for c-Kit, but more data from many centres is needed.

Checked line by line against the paper: 26 Oct 2026.

Surgeons in Sarajevo describe a woman with a 22 cm FATWO filling her tummy and pelvis, with raised ovarian cancer blood markers, which was removed completely and had not come back six months later.

The patient or patients

One woman aged 68, treated at a general hospital in Sarajevo, Bosnia and Herzegovina. For three months she had noticed a painless swollen tummy and needing to pass urine often, and she could feel a large lump in her lower tummy. She had had her womb (but not her ovaries) removed 12 years earlier for fibroids.

What doctors did

Ultrasound and CT scans showed a 22 x 21 cm mass in the tummy and pelvis, more on the right, with solid and fluid-filled parts. The liver was slightly enlarged with a single 8 mm spot. Blood tests were raised: CA-125 185.9 U/ml and HE4 228.3 pmol/l, and the ROMA risk score was high at 79.9%. At open surgery, the tumour filled the whole tummy and pelvis. It had a capsule but was stuck to the omentum, the bowel's supporting tissue and nearby tissue, with large blood vessels feeding it. The whole tumour was removed, along with both ovaries and tubes. Under the microscope, the cells formed tube-like, island and sieve-like patterns. The cells showed mild to moderate abnormality and few dividing cells. There were areas of fluid-filled change and dead tissue. Stains were positive for CK19, cytokeratin AE1/AE3, CK18, inhibin, vimentin and EMA, with rare single cells positive for CK5/6 and CK7. The liver spot was tested and turned out to be a harmless blood vessel growth (cavernous haemangioma), with no tumour cells.

What happened

Recovery after the operation went smoothly. At six months, an MRI scan of the tummy and pelvis showed no sign of the tumour coming back, and her tumour marker blood tests were back in the normal range. This is a single case, so it can't tell us what will happen to others.

Why it matters

It is among the largest FATWOs reported. It also shows that CA-125 and HE4 can be raised in FATWO, even though in most reported cases they are normal before surgery. The authors note from earlier studies that FATWO can come back years later, even without worrying features under the microscope, and that most returns have been reported in women who had only the tumour removed.

Checked line by line against the paper: 26 Oct 2026.

Pathologists in Cleveland, USA, studied 11 FATWOs from their centre and found that the stains CD10 and AE1/3 were positive in every case tested and PAX8 and GATA3 almost always negative, concluding that FATWO is diagnosed by ruling out other tumours.

Written from the abstract only (full text could not be opened).

The patient or patients

Eleven women with FATWO from one institute in Cleveland, Ohio, aged 25 to 76 (average 55). Tumours were 0.5 to 18 cm across (the abstract gives an average of 2.7 cm).

What doctors did

The team reviewed the clinical details, the appearance under the microscope and stain results for all 11 tumours. Most tumours looked low grade, with few dividing cells and no dead tissue. Three main growth patterns were seen: solid, tube-like and sieve-like. Two tumours had more abnormal-looking cells, more dividing cells and small areas of dead tissue; these two were considered malignant FATWO, mainly because the tumour was found outside the adnexa. Stain results: CD10 positive in 11 of 11; AE1/3 positive in 8 of 8; CAM 5.2 in 4 of 5; CK7 in 7 of 10; and patchy positive for calretinin (4 of 10), inhibin (4 of 10), EMA (3 of 9) and SF-1 (2 of 8). PAX8 and GATA3 were negative in almost all cases.

What happened

The authors report that all patients with follow-up information had a favourable outcome. The abstract does not give follow-up lengths or say whether any tumours came back.

Why it matters

It adds a series of 11 cases to a very small body of evidence on how FATWO looks in the lab. The lack of PAX8 and GATA3 suggests, in the authors' view, that FATWO is different from tumours of Müllerian or mesonephric origin. Because the features overlap with other tumours, they conclude FATWO is a 'diagnosis of exclusion' until better gene and stain markers are found.

Checked line by line against the paper: 26 Oct 2026.

US pathologists describe a 79-year-old woman with a small FATWO in her left ovary, removed by keyhole surgery without taking out the womb, and explain why FATWO is hard to diagnose from the quick microscope check done during an operation.

The patient or patients

One woman aged 79 with no other known health problems, treated in the USA. She had tummy discomfort. A scan showed a mass by her left ovary. Her routine blood tests and tumour markers (CEA, CA19-9 and CA125) were normal.

What doctors did

She had keyhole surgery to remove the left ovary and tube, and the surgeon asked for a quick microscope check (frozen section) during the operation. The ovary looked cystic, with solid nodules smaller than 1 cm that were yellow when cut. Under the microscope the cells were rounded to spindle-shaped, arranged in sieve-like and tube-like patterns, with some pink secretions and some grooved nuclei. Stains showed the tumour was positive for Pan-cytokeratin, CD10 and CD117 (c-kit), and negative for PAX8, CK20, CEA and SF1. It was classed as a Wolffian adnexal tumour (WAT). Because of this, the team decided not to go on to remove the womb. She was kept on regular check-ups.

What happened

She recovered well after surgery. At two years there was no sign of the tumour coming back and no tumour left behind. This paper also reports survival figures, which we have left out of this summary. This is a single case, so it can't tell us what will happen to others.

Why it matters

The authors explain that FATWO can look like several other tumours, especially granulosa cell tumours, ovarian endometrioid cancer and Sertoli-Leydig cell tumours. During an operation, stains cannot be used, so the quick check is hard. Getting the diagnosis right matters because it can spare a woman a bigger operation, as here. The authors say FATWO usually behaves in a benign way but some come back, sometimes more aggressively, so they recommend long-term follow-up. In their review of earlier papers they note that no gene change specific to FATWO has been found, though changes in genes including STK11 have been reported; later papers treat tumours with STK11 changes as a separate type (STK11 adnexal tumour). This patient's tumour was not gene tested.

Checked line by line against the paper: 26 Oct 2026.

Pathologists in Himachal Pradesh, India, describe a woman with large FATWOs in both ovaries (17 cm and 16 cm), which were suspected to be ovarian cancer before surgery and diagnosed as FATWO after lab tests and stains.

The patient or patients

One woman aged 55, past the menopause, with tummy pain and a swollen tummy. She had had her womb removed seven years earlier for fibroids. The paper does not say how long her symptoms had lasted.

What doctors did

A CT scan of the tummy showed solid and fluid-filled masses in the tummy and pelvis that lit up unevenly with dye. CA-125 was mildly raised at 62.2 units/mL; CEA and CA 19-9 were normal. Doctors suspected ovarian cancer. The masses were removed by surgery. The lab received both ovaries with their fallopian tubes attached, measuring 17 x 16 x 14 cm and 16 x 10 x 6 cm, and a 30 x 5 cm piece of omentum. Both ovarian masses had an intact capsule with a lumpy, lobed surface; inside they were solid and pale yellow to grey-white. The omentum had no lymph glands or tumour deposits. Under the microscope, the tumour grew in nodules with nests, cords, bands and small tubes or glands containing bright pink secretions. The cells had mildly varied round nuclei, some with grooves, and only occasional dividing cells. Stains: pancytokeratin, CK7 and CD10 positive; PAX8, CK20 and CEA negative. This confirmed FATWO of both ovaries.

What happened

The paper does not report any follow-up after surgery. The authors say the outlook for this tumour cannot be accurately predicted, and that the usual treatment described in the literature is removal of the womb with both ovaries and tubes, because the tumour can come back; the role of chemotherapy or radiotherapy is unclear. This is a single case, so it can't tell us what will happen to others.

Why it matters

It describes FATWO in both ovaries at once, which is unusual, and shows that CA-125 can be mildly raised. It also shows how FATWO can be mistaken for ovarian cancer before surgery, and how careful lab work and stains are needed to reach the diagnosis.

Checked line by line against the paper: 26 Oct 2026.

In one woman whose FATWO kept coming back and had an STK11 gene change, the tumour shrank for over a year on everolimus (an mTOR inhibitor) plus anastrozole (a hormone tablet).

The patient or patients

One woman, aged 29, from Brazil. She had pelvic pain from December 2015 that did not settle with painkillers or the contraceptive pill. An ultrasound showed a 2.6 cm cyst-like area in the left ovary. This is a single case, so it can't tell us what will happen to others.

What doctors did

May 2016: an operation removed the lump and left fallopian tube; it was a 9 cm FATWO beside the tube with many dividing cells. December 2016: it came back as several nodules on the tummy lining (largest 4.5 cm); she had a hysterectomy, removal of both tubes and ovaries and the omentum, and all nodules were removed, followed by four cycles of BEP chemotherapy. July 2018: a 1.9 cm lump near the duodenum was removed by keyhole surgery, followed by four cycles of TIP chemotherapy. August 2019: it came back on the tummy lining in a way that could not be operated on. Next-generation sequencing of the tumour found an STK11 change (L55fs*108). Because of this, and because the tumour had hormone receptors, she started everolimus 10 mg a day and anastrozole 1 mg a day.

What happened

On everolimus and anastrozole the tumour partly shrank and stayed smaller for more than a year. In January 2021 it grew again, but she was then able to have surgery that removed all visible tumour. Tests on that tumour now showed c-Kit (CD117) on its cells, so in February 2021 she started imatinib. At the time of writing there was no sign of the tumour and she was continuing imatinib.

Why it matters

It was reported as the first FATWO with an STK11 change treated with an mTOR inhibitor, and it suggests gene testing (looking for STK11) may be worth considering in FATWO that comes back, as it may point to a targeted treatment. The authors also say that an STK11 change in the tumour should prompt thinking about testing for an inherited change (Peutz-Jeghers syndrome). It is one case, so larger studies are needed before anyone knows whether this treatment helps others.

Checked line by line against the paper: 26 Oct 2026.

A team in New York, USA, describes a 28-year-old whose small FATWO was removed by keyhole surgery and then appeared as small lumps at the belly-button cut used to take it out, eight months later, and reviews earlier published cases of FATWO that came back or spread.

The patient or patients

One woman aged 28, who had had more than one child, treated at Northwell Health in New York, USA. She came to the emergency department with one day of pain low on the left side of her tummy. An ultrasound showed a 3.5 cm solid mass with fluid areas on the left, which looked like an ovarian growth on a stalk that might be twisting. The paper also includes a table of earlier published cases of malignant FATWO (ages 15 to 81).

What doctors did

She had keyhole surgery for a suspected twisted ovary. Instead, surgeons found a cyst beside the left fallopian tube, with no twisting. They separated it from the tissue holding the tube and took it out in a specimen bag through the belly-button cut. The lab result was FATWO. Afterwards a chest CT scan was normal, CA-125 was 12 and inhibin B was 82. About two months after surgery she had a smelly discharge from the belly-button wound, which was an infection (Proteus mirabilis and Streptococcus agalactiae) and cleared with antibiotic tablets. When the tumour came back, she was first treated for a possible pelvic infection (pelvic inflammatory disease), then had an operation to remove the belly button area (umbilectomy) and the left tube and ovary. Table 1 records that treatment with imatinib (Gleevec) was recommended afterwards. The tumour stained positive for c-Kit, the protein this drug targets.

What happened

After the first operation she went to the emergency department several times with tummy pain, but scans were normal. Eight months after the first operation she had severe pain around the belly button. A CT scan showed several small rounded lumps, 9 mm or less, in the tummy wall at the belly button, and one 7 mm lump beneath the tough sheet that covers the tummy muscles (the rectus aponeurosis). A 1 cm lump could be felt in the base of the belly button. The removed belly-button tissue contained several firm nodules of 0.9 to 1.4 cm, which looked almost the same as the original tumour under the microscope and had similar stain results. The left tube and ovary removed at the same time were not affected. The authors say it is unclear whether this was a true return of the tumour or tumour cells seeded into the wound when the specimen was taken out, although a retrieval bag was used and no spillage was reported. They also wonder whether her earlier pain visits could have been linked to inflammation from seeded tumour. This paper also reports survival figures, which we have left out of this summary. This is a single case, so it can't tell us what will happen to others.

Why it matters

It shows a FATWO reappearing at the keyhole wound used to remove it, which the authors suggest might be seeding during removal. From their review of published cases, the authors say upwards of 25% of published FATWO cases had a return or spread, higher than an earlier 2009 estimate of 11%, and they suggest FATWO may be best thought of as a tumour of low malignant potential. They note that extra treatment after the first operation was usually not recommended in past cases, and that after a return, repeat surgery followed by chemotherapy (most often carboplatin and paclitaxel) or radiotherapy was used with mixed success. They say stains may help guide treatment: this tumour stained for oestrogen and progesterone receptors and for c-Kit, and imatinib has been used with some success in earlier c-Kit-positive cases. The authors advise close follow-up because outcomes vary. No gene testing was reported.

Checked line by line against the paper: 26 Oct 2026.

Romanian doctors describe a 43-year-old woman whose FATWO came back about six years after surgery and then several more times, despite repeated operations and four different chemotherapy plans, and they compare five earlier reported cases.

The patient or patients

One woman aged 43, treated at a cancer centre in Romania. The paper does not describe her first symptoms. Her first tumour was 7 cm and was described as of 'uncertain malignant potential' (a borderline tumour).

What doctors did

In 2010 she had her womb removed along with an ovarian cyst. No extra treatment was given; she had check-ups. When the tumour came back in 2016, surgeons removed both ovaries and tubes, the omentum and some lymph glands, but small spots (under 1 cm) were left on the tummy lining. She then had 6 rounds of carboplatin. When it came back again later in 2016, surgeons removed lymph glands and burned away spots on the tummy lining, and she had 6 rounds of paclitaxel with carboplatin. When it came back a third time in 2017, surgeons removed all visible tumour and she had 3 rounds of carboplatin with etoposide. When it came back a fourth time in 2018, surgeons removed the new spots and she had up to 4 rounds of topotecan. The authors also review five earlier reported women whose malignant FATWO came back.

What happened

The first return was about 6 years after the first operation and was widespread: spots in the liver, lymph glands at the back of the tummy and in the pelvis, fluid in the tummy and spots on the tummy lining, with a raised CA-125 of 420.5 U/mL. The paper does not clearly say how the tumour responded to carboplatin alone. After paclitaxel with carboplatin, a scan showed new spots on the tummy lining. After carboplatin with etoposide, a scan showed new spots under the liver surface and in tummy fat. The response to topotecan is not described. In their review of five earlier cases, the authors write that platinum chemotherapy often did not work well, and that the best responses were in two women who had surgery together with imatinib, a targeted tablet. Only one of the five had hormone treatment (leuprolide), and the tumour grew. This paper also reports survival figures, which we have left out of this summary. This is a single case, so it can't tell us what will happen to others.

Why it matters

It shows that FATWO can come back many years after the first operation, which supports long-term follow-up. It records in detail which chemotherapy plans were tried one after another, which may help doctors who have very little to go on. The authors suggest testing tumours that come back for a marker called c-KIT, but this is their suggestion, not a proven approach.

Checked line by line against the paper: 26 Oct 2026.

A Chinese team describes a 75-year-old woman whose FATWO came back three years after it was first removed, was treated with a second operation and six cycles of docetaxel and carboplatin chemotherapy, and showed no sign of coming back two years later; they also review 28 earlier published women whose FATWO came back or spread.

The patient or patients

One woman aged 75, past the menopause, treated at West China Second University Hospital in Chengdu, China. In 2015 she had an 8 cm FATWO growing from the broad ligament (the sheet of tissue beside the womb) on her right side. In October 2018 a routine ultrasound check found a new 3.6 x 4.4 x 3.8 cm part-solid, part-fluid lump on the right side of the womb. She had no symptoms: no bleeding, no tummy pain and no swelling. Her blood tests, including the tumour marker CA-125, were normal. The paper also reviews 28 earlier published patients (aged 15 to 81) whose FATWO came back or spread, from 26 studies published between 1976 and 2017.

What doctors did

First operation (2015, at a local hospital): open surgery found the lump with no other disease in the pelvis or tummy. The lump was simply cut out, and both ovaries and tubes were removed as a precaution. Two outside expert pathologists agreed it was likely a FATWO. Second operation (2018): keyhole surgery (laparoscopy). The 5 x 4 cm lump was stuck firmly to the back of the right broad ligament, the right back wall of the womb and the small bowel. Surgeons removed the lump and the womb, and took fluid washings from the tummy. The abstract also describes removal of a lesion in the small bowel. Under the microscope the tumour was mostly solid with some fluid-filled areas, and the cells looked fairly bland with few dividing cells. Stains: CK7, Vimentin, EMA, TTF-1, CD10, Pax-8, Pax-2, P16 and CA125 were positive; ER, PR, AR, CEA, α-inhibin, CD56 and CK20 were negative. Ki-67 (a measure of how fast cells are dividing) was about 60%. After comparing with the slides from 2015, the final diagnosis was recurrent and metastatic FATWO, staged as FIGO IIIC. A cancer specialist advised chemotherapy, and she had 6 cycles of docetaxel (80 mg/m2) and carboplatin (300 mg/m2), starting 3 weeks after the second operation. She was then checked regularly with chest and tummy CT scans and tumour marker blood tests. No gene testing is reported.

What happened

The FATWO came back three years after the first operation, in the right side of the pelvis, attached to the womb and small bowel. After the second operation and chemotherapy there was no sign of it coming back at 2 years. The authors say she had a good response to the chemotherapy with no side effects. In their review of earlier cases, the time until the tumour came back or spread ranged from 4 to 96 months (middle value 33.5 months), and some women had it come back more than once. The most common places it spread to were the omentum and the lining of the tummy, followed by the liver, the outside of the bowel, the lung and the area beside the vagina. Most of the women whose tumour came back had first been treated by removing the tumour alone. The authors say earlier chemotherapy combinations had results that were 'not satisfactory'. This paper also reports survival figures, which we have left out of this summary. This is a single case, so it can't tell us what will happen to others.

Why it matters

In this case there was no sign of the FATWO coming back two years after a second operation and docetaxel-carboplatin chemotherapy. The authors conclude that complete surgery (removing the womb, both ovaries and tubes, and as much tumour as possible) followed by combination chemotherapy is considered the most effective treatment for FATWO that has come back or spread, and that docetaxel plus carboplatin 'may be effective'. They say further studies are needed to confirm this. The review table is a useful list of 28 earlier published women whose FATWO came back or spread, with the treatments they had. No gene testing was done, so it is not known whether this tumour had an STK11 change; later papers treat STK11-changed tumours as a separate type.

Checked line by line against the paper: 26 Oct 2026.

US pathologists compare one FATWO with one mesonephric-like carcinoma of the ovary, showing how the two differ in loose-cell (cytology) samples, tissue sections and stains.

Written from the abstract only (full paper not free).

The patient or patients

Two patients seen at Inova Fairfax Hospital, Virginia, USA: one with a FATWO and one with a mesonephric-like carcinoma (MLC) of the ovary. Both tumours are thought to come from Wolffian (mesonephric) remnants. The abstract gives no ages or symptoms.

What doctors did

The pathologists compared the cells seen in cytology samples with the tissue under the microscope, and ran stains on both tumours.

What happened

In the FATWO, cytology showed small, oval to spindle-shaped, uniform cells with no dividing cells (mitoses). Some cells had small bubbles (vacuoles) beside the nucleus and sat singly or in loose clusters; others were in tight clusters around glassy basement-membrane-like material. In the tissue sections, the FATWO had areas that looked like thyroid tissue, as did the carcinoma. The FATWO cells were positive for CK AE1/AE3, calretinin, WT-1, inhibin and CD10, and negative for CK7, PAX-8, GATA-3, ER, PR and C-kit. In contrast, the carcinoma cells were positive for CK7, CD10, PAX-8, TTF-1 and GATA-3, and negative for ER, PR and WT-1. The carcinoma also showed tight three-dimensional cell clusters, tubes and finger-like (papillary) shapes.

Why it matters

FATWO and mesonephric-like carcinoma can both show thyroid-like features, so they can be confused. This report shows that the cell appearance and a panel of stains (especially WT-1, calretinin, inhibin, PAX-8 and GATA-3) can help pathologists tell them apart. It describes only one FATWO.

Checked line by line against the paper: 26 Oct 2026.

Pathologists in Montenegro describe a woman whose 8 cm FATWO inside her left ovary was found at a routine gynaecology check, removed with her womb, ovaries and tubes, and had not come back a year later.

The patient or patients

One woman aged 64, treated in Montenegro. She had been through the menopause 12 years earlier and had two children. The tumour was found during a routine gynaecological examination. Her symptoms were vague; she later mentioned bloating and discomfort in the pelvis. She was otherwise well and not being treated for other illnesses.

What doctors did

Ultrasound (through the tummy and internally) showed a solid, even-looking mass where the left ovary would be. A CT scan supported an ovarian tumour. Blood tumour markers (CA-125, CA 15-3, CA 19-9 and CEA) were normal. An ultrasound of the tummy and a chest X-ray showed no changes in other organs. At open surgery, the womb and both ovaries and tubes were removed. The left ovary contained an 80 x 60 x 50 mm tumour with a smooth, shiny, whitish surface, partly solid and partly fluid-filled. Under the microscope the cells were fairly uniform and arranged in solid, cord-like and tube-like patterns. There was no dead tissue, dividing cells were very rare (1 to 2 per 10 high-power fields), and the tumour had not grown through the ovary's outer layer. Stains: positive for pancytokeratin (CK), CK7, CD10 and synaptophysin; individual cells positive for calretinin, progesterone, oestrogen, EMA and NSE; negative for inhibin, CD20, CDX2, WT1, CD56, CD125, TTF1, PAX8, p16, mammaglobin, GATA3, GCDFP15 and chromogranin. Ki-67 was less than 1%. The diagnosis was FATWO. Because the authors regard FATWO as having real potential to behave like a cancer, she was advised to have regular check-ups with examinations, tummy ultrasound and chest X-rays.

What happened

One year after the operation, there were no signs of the tumour coming back or spreading. This is a single case, so it can't tell us what will happen to others.

Why it matters

It adds another FATWO arising inside the ovary itself, which is less common than in the broad ligament, and gives a detailed stain profile. The authors stress that no single stain proves FATWO; CD10 positive with PAX8 negative is described in the literature as the most helpful combination. They say the main treatment is complete surgical removal, while chemotherapy and radiotherapy have an uncertain role for FATWO that comes back.

Checked line by line against the paper: 26 Oct 2026.

Japanese radiologists describe the MRI, CT and PET-CT scans of four women with Wolffian tumours that turned out to be benign, showing that these tumours can look like cancers on some scans.

The patient or patients

Four women from four hospitals in Japan, aged 27, 39, 60 and 66. Two (aged 60 and 66) had no symptoms; their tumours were found by chance during check-ups for other conditions (lymphoma and diabetes). The other two (aged 27 and 39) came in with sudden lower tummy pain.

What doctors did

All four had MRI before surgery; three also had CT, and two had PET-CT. Two radiologists reviewed all the scans together. The tumours were 50 to 70 mm, well-defined and mostly solid; two contained fluid-filled areas and one had small chalky spots. In the two younger women, the normal ovary could be seen separately from the tumour; in the two older women it could not. On diffusion MRI, all three tumours tested were bright, which usually suggests tightly packed cells. On PET-CT, both tumours tested took up a moderate amount of sugar tracer (SUVmax 4.2 and 8.2), above levels other studies have used to suggest cancer in ovarian tumours. Tumour markers CA 19-9 and CA-125, checked in two women, were normal. Three women had one ovary and tube removed; one woman with no symptoms had both removed. None had a hysterectomy or lymph gland removal. The tumours were treated as benign because they were well-defined and showed no spread on scans. At surgery they were found in the left broad ligament, left ovarian hilum, left mesosalpinx and right mesosalpinx. In the 27-year-old, the tumour had twisted twice round (720 degrees) together with the right fallopian tube. In the 39-year-old, there was bleeding inside the tumour but no twist was seen at surgery.

What happened

Under the microscope, all four tumours were diagnosed as benign, without a high rate of dividing cells or abnormal-looking cells. The twisted tumour had dead tissue and bleeding; the tumour with bleeding also had areas of dead tissue, which the authors think may mean it had twisted earlier. The paper does not report any follow-up after surgery. The cases in this small series are individual examples, and four cases can't tell us what will happen to others.

Why it matters

The authors say this was the first description of how Wolffian tumours look on PET-CT. They found that even benign Wolffian tumours can light up on PET-CT and diffusion MRI, so these scan results do not on their own mean a tumour is cancer. They suggest that a solid tumour sitting separately from a normal ovary should make doctors think of a Wolffian tumour, especially in younger women. They also note these tumours can twist and cause sudden pain.

Checked line by line against the paper: 26 Oct 2026.

Doctors in Toronto describe a 63-year-old woman whose FATWO had already spread inside her tummy, which was fully removed by surgery, and they review what is known about treating these tumours.

The patient or patients

One woman aged 63, past the menopause, treated in Toronto, Canada. She came to doctors with a tender lump in the lower right side of her tummy. Her CA-125 blood test was normal (27 U/mL).

What doctors did

An MRI scan showed a 12 cm lumpy mass and a 5.7 cm fluid-filled cyst. A CT scan showed small nodules on the lining of the tummy and some lymph glands that were at the upper limit of normal size but looked abnormal, which suggested the tumour had spread. She had an open operation to remove the womb, both ovaries and tubes, the lining of the pelvis, the omentum (fatty apron), the nodules and some lymph glands. No visible tumour was left. Under the microscope it was a 13 cm mostly solid tumour of the right ovary area that had spread to both ovaries and tubes, the outer surface of the womb, the omentum, the side wall of the pelvis and the outside of the lower bowel. The two lymph glands tested were clear. Stains on the tumour cells confirmed FATWO. The doctors advised regular check-ups (surveillance) rather than extra treatment.

What happened

The tumour was completely removed and she was discharged after 3 days. The paper does not describe her tumour coming back or any further treatment. In their review, the authors write that FATWO comes back in about 10 to 20 in every 100 patients, and that the middle (median) time before it comes back is 48 months. For tumours that come back, they write that carboplatin with paclitaxel is the only combination reported to have held tumours steady or shrunk them; imatinib was used in three reported cases with mixed results; pegylated liposomal doxorubicin helped in one case but was stopped because of side effects; and hormone treatments (leuprorelin, medroxyprogesterone, tamoxifen) showed no clear benefit. This is a single case, so it can't tell us what will happen to others.

Why it matters

It brings together, in a short article, what was known in 2021 about treating FATWO, including after it comes back. It supports complete surgical removal as the main treatment and describes the check-up schedule these authors use (an examination and CT scan every 4 to 6 months for the first 2 to 3 years, then yearly). It also reminds readers that there is no standard extra treatment after surgery, because so few cases have been studied.

Checked line by line against the paper: 26 Oct 2026.

A short conference report describes a 55-year-old woman with no symptoms whose adnexal lump turned out to be a Wolffian tumour (FATWO) on the right fallopian tube, removed by keyhole surgery in two stages.

The patient or patients

One woman aged 55, past the menopause, with no symptoms. She was referred because a lump had been found near her womb and ovaries. Ultrasound showed a fibroid and a partly fluid-filled, partly solid lump of about 8 x 4 cm low in the pelvis behind the womb (the pouch of Douglas). A Doppler scan showed no blood flow signal in it. Her CA-125 and CEA blood markers were normal.

What doctors did

Keyhole surgery removed both tubes and both ovaries. During it, a twisted lump of about 6.5 x 4 cm, partly solid and partly fluid-filled, was found on the right fallopian tube and removed with them. The first microscope report called it an undifferentiated tumour. Stain tests then showed it was a Wolffian tumour. A CT scan of the tummy and chest found no spread. A tumour board (a team meeting of specialists) then recommended removing the womb, which was done by keyhole surgery, along with tissue samples from inside the tummy. These samples were clear.

What happened

The report says the time after surgery was uneventful. It does not describe how she did over the longer term. The authors advise regular long-term follow-up. This is a single case, so it can't tell us what will happen to others.

Why it matters

It shows a FATWO growing on the fallopian tube itself, found by chance in a woman with no symptoms, and twisted on itself. The authors note that because so few cases exist, there is little information on how these tumours behave or how best to treat them. They say complete removal, including the womb and both tubes and ovaries, is thought to work best, because removing the lump alone carries a risk of it coming back, and that the value of extra chemotherapy or radiotherapy is still unclear.

Checked line by line against the paper: 26 Oct 2026.

An Indian pathology team describes a 47-year-old woman with six months of tummy pain and a lump, whose 7 cm tumour beside the right fallopian tube was confirmed as FATWO using stain tests.

The patient or patients

One woman aged 47 who had been pregnant once. She had tummy pain and a lump in the lower right tummy for six months. She had no important past illnesses. A pelvic examination and ultrasound showed a 7 x 5 x 4 cm solid lump in the region of the right fallopian tube.

What doctors did

She had an open operation to remove the womb (hysterectomy). The lump was found to be completely separate from the right tube and ovary, with no blood-vessel stalk. It was removed together with the womb and cervix and sent to the lab. Under the microscope the lump was well enclosed in a capsule, solid, and greyish-yellow. It showed solid areas and packed tube-like shapes. The cells were uniform, with no marked variation in shape and no dividing cells seen. Stain tests were positive for WT (diffuse) and CD99 (patchy), and negative for EMA, CK20, calretinin and PAX8.

What happened

Her recovery after the operation was uneventful. The paper does not report any follow-up after that. The authors advise long-term follow-up after treatment. This is a single case, so it can't tell us what will happen to others.

Why it matters

It shows how pathologists used a panel of stains to tell FATWO apart from look-alike tumours, such as serous and endometrioid tumours, adenomatoid tumour, granulosa cell tumour and Sertoli-Leydig cell tumour. The authors note there is no single stain specific to FATWO. They say most FATWOs behave in a benign way, though cancerous ones have been reported.

Checked line by line against the paper: 26 Oct 2026.

An Iranian team describes a 32-year-old woman with two FATWO lumps beside the left fallopian tube, which were removed along with the tube while her womb and ovaries were kept, with no sign of the tumour coming back at 20 months.

The patient or patients

One woman aged 32 who had been pregnant four times (one birth and three miscarriages). She was being checked for vaginal discharge when ultrasound found a 6 x 6 cm solid lump next to the left ovary and a small polyp inside the womb. MRI confirmed a 6.5 x 6.5 cm lump in the left broad ligament. Her blood markers were CA-125 26 u/mL, CA19-9 7 u/mL and CEA 0.5 ng/mL. A chest X-ray was normal.

What doctors did

First, the womb polyp was removed through a camera in the womb (hysteroscopy); the lab showed a polyp of the womb lining. Then, at an open operation, two solid lumps were found beside the left tube in the broad ligament, separate from the left ovary: one about 10 x 10 cm and one about 2 x 3 cm. No other lumps were seen in the tummy. A rapid test during the operation (frozen section) raised the possibility of a Sertoli cell tumour, but because of where the lumps were and the normal ovary, a Wolffian tumour seemed more likely. So only the lumps and the left fallopian tube were removed; the womb and ovaries were kept. In the lab, the smaller lump showed sieve-like and tube-and-cyst patterns, some dead tissue (necrosis) and 5 dividing cells per 10 high-power fields. Tumour cells had grown into the outer and muscle layers of the left fallopian tube. Stains were positive for calretinin, inhibin, vimentin, CD56, WT1, CK7 and CK19, and negative for EMA, CD10, AFP and Glypican-3.

What happened

She left hospital without complications. Ultrasound checks over 20 months showed no sign of the tumour coming back. This is a single case, so it can't tell us what will happen to others.

Why it matters

It shows that, in a young woman, surgery that keeps the womb and ovaries was used. The authors point out that growth into the tube wall is an invasive feature doctors should take note of. They describe FATWO as a low-grade cancer and recommend that pathologists use a wide range of stains, and that patients are followed up over the long term until more is known. They also cite earlier reports that, when only the tumour is removed, most returns happen within two years.

Checked line by line against the paper: 26 Oct 2026.

FATWO tumours looked very varied under the microscope and with stains, but few had harmful gene changes, which the authors suggest may help tell FATWO apart from look-alike tumours.

Written from the abstract only (full paper not free).

The patient or patients

15 patients aged 32 to 69 (average 47). Tumours measured 1.8 to 30 cm (average 10 cm). All but one grew in the soft tissue beside the womb, tubes and ovaries. The abstract does not say which countries the patients came from or how the tumours first showed up.

What doctors did

Specialist doctors who study tissue (pathologists) looked at the tumours under the microscope, tested them with a range of stains (immunohistochemistry) and read their DNA to look for gene changes and copy number changes.

What happened

Every tumour had tube-shaped (tubular) areas. Many also had solid areas (11 of 15) or a 'sieve-like' pattern (7 of 15). Most (12 of 15) had only mild cell changes, but three had small areas of more abnormal-looking cells. All tumours were positive for the stain pankeratin and negative for TTF-1. Other stains (such as EMA, GATA3 and PAX8) were positive only rarely and in small patches, and several others varied from tumour to tumour. Harmful gene changes were rare: STK11 in three tumours, APC in one and MBD4 in one. The three tumours with STK11 changes also had a jelly-like (myxoid) background and copy number changes. Follow-up information was available for only six patients. This paper also reports survival figures, which we have left out of this summary.

Why it matters

It shows that FATWO can look very different from one tumour to the next, which is why it is hard to diagnose. Most FATWOs in this study had few gene changes, unlike tumours that look similar, which may help pathologists in difficult cases. The small group of tumours with STK11 changes was an early clue that led the same research team to describe a separate tumour type (see FW-166).

Checked line by line against the paper: 26 Oct 2026.

This 2020 review explains how FATWO looks under the microscope and on tests, notes that fewer than 90 cases had been described in English, and says there is no agreed best treatment.

Written from the abstract only (full paper not free).

The patient or patients

A review of fewer than 90 published cases, plus cases from the University of Mississippi Medical Center (USA). The abstract says FATWO affects women across a wide age range and has no typical set of symptoms.

What doctors did

The authors reviewed published papers, book chapters and their own hospital's cases, looking at clinical features, how the tumour looks to the naked eye and under the microscope, staining tests, and other tumours it can be mistaken for.

What happened

FATWO is usually a solid tumour, sometimes with lumpy, lobed or cyst-like parts. Under the microscope it can show many different patterns, which can make diagnosis hard. No single stain is specific to FATWO, and how it develops and its gene changes were not yet well understood. It is generally thought of as benign, but cases that came back or spread have been reported. There were no current recommendations on the best treatment.

Why it matters

Because FATWO can look like several other tumours, this review helps pathologists recognise it and get the diagnosis right. For families, it explains why the diagnosis can be difficult and why doctors may not have a set treatment plan to follow.

Checked line by line against the paper: 26 Oct 2026.

American doctors describe a woman whose FATWO, first judged low-grade, came back two years later as several pelvic lumps that looked more aggressive under the microscope, and was treated with surgery and carboplatin-paclitaxel chemotherapy.

The patient or patients

One woman, now aged 47, who had had two children. The authors are based in New Jersey, USA. At 45 she had a few months of on-and-off pain and pressure in the lower right side of her tummy. An examination found a lump on her right side, and an ultrasound showed a 10 x 9 x 9 cm solid lump. Her tumour marker blood tests (CA-125, AFP and HCG) were normal. The lump was not part of her tubes, ovaries, womb or cervix.

What doctors did

First operation (age 45): surgery began as keyhole surgery, but the lump burst while being removed, spilling about 200 mL of blood, so it was changed to open surgery. A quick test during the operation suggested a granulosa cell tumour or a Wolffian tumour. Surgeons removed the womb, the right ovary and tube and the left tube, removed tumour from the pelvis, removed lymph nodes on the right side of the pelvis, and took samples of the tummy lining and the omentum. The left ovary was left in place because the tumour looked harmless and because of her age. Under the microscope, few cells were dividing and they did not look abnormal. The PAX8 stain was negative and the fluid washings had no cancer cells. It was diagnosed as a low-grade Wolffian tumour and no further treatment was needed. There was no sign of it coming back for the rest of that year. Second operation (two years later): open surgery removed the left ovary and the pelvic lumps, and a rigid camera was used to look inside the back passage. Surgeons found a 3 cm cyst on the left ovary attached to the left pelvic wall, and a 5 cm lump between the top of the vagina and the back passage, which burst while being removed. Because of concern it was cancerous, extra stains and outside expert opinion were obtained. Stains: AE1/3, CD10, PAX-8, CK19, CD56 were positive; calretinin, BerEP4 and p16 were positive in places; WT1 was patchy. EMA, inhibin, melanin A, chromogranin and synaptophysin were negative. Ki-67 was 20%. Because of the stain findings and the high number of dividing cells, she chose to have chemotherapy: carboplatin and taxol (paclitaxel) every 3 weeks for 4 cycles. No gene testing is reported.

What happened

The tumour came back two years after the first operation. At that point she had widespread tummy pain, blood in her urine, pain passing urine, pain around the back passage, difficulty emptying her bladder, right pelvic pain spreading to her side and back passage, light vaginal bleeding, pain during sex, weight gain of 20 pounds and long-term constipation. Tests on her urinary system found nothing significant. Ultrasound found three lumps in the pelvis (3.5 x 3.5 x 4.3 cm, 1.9 x 1.7 x 1.7 cm and 5.0 x 3.3 x 2.7 cm), and a CT scan confirmed a lump on the left ovary and a lump in the left pelvis above the top of the vagina, next to the back passage. The returned tumour looked more aggressive under the microscope than the first: many dividing cells, crowded cells, very varied cell shapes and large nucleoli. Unusually, the first tumour was PAX8 negative but the returned tumour was PAX8 positive. She was having chemotherapy when the paper was written, so the paper does not say how well it worked. This is a single case, so it can't tell us what will happen to others.

Why it matters

This case shows a FATWO that looked harmless at first coming back with features of a malignant tumour. The authors say a FATWO is judged malignant by whether it comes back and spreads, and that stain results must be read with caution because they can vary, as shown by the change in PAX8. They say symptoms from pressure on the bladder and bowel 'should raise suspicion of recurrence'. They found no evidence that keeping the left ovary caused the tumour to come back. The authors say there is not enough evidence to recommend particular targeted medicines for FATWO, though gene testing could help if a treatable change is found. For follow-up, they borrow from ovarian cancer guidance (NCCN): if fertility-sparing surgery was done, scans every 3 to 6 months for at least 2 years seems reasonable. No gene testing was done, so it is not known whether this tumour had an STK11 change; later papers treat STK11-changed tumours as a separate type.

Checked line by line against the paper: 26 Oct 2026.

A Boston hospital team describes two women, aged 43 and 57, whose FATWOs were removed by keyhole surgery and who needed no further treatment, with routine check-ups recommended.

The patient or patients

Two women treated at Brigham and Women's Hospital, Boston, USA. Case A: aged 43, before the menopause, with sudden pain low on the right side of the tummy. A CT scan first suggested a 7 cm right ovary with a dermoid cyst. A repeat ultrasound showed a 6.5 cm lump, partly calcified, next to but seemingly separate from the right ovary. Pregnancy scans 9 years earlier had shown a 4 cm lump in the same place, thought at the time possibly to be a fibroid of the broad ligament. Her CA-125 was 10 U/mL, CEA 1.6 ng/mL and CA19-9 7 U/mL. Case B: aged 57, past the menopause, with blood-tinged vaginal discharge and no tummy pain. Ultrasound showed an irregular solid lump of about 8 to 9 cm on the right with moderate blood flow. A sample of the womb lining showed no cancer. Her CA-125 was 10 U/mL.

What doctors did

Case A: keyhole surgery found the lump beside the right fallopian tube, twisted on itself. The right tube and ovary were removed. A rapid test during the operation favoured FATWO. As there was no visible spread and low concern for an aggressive tumour, no further staging surgery was done. The final lab report showed a 6.8 cm FATWO. Stains were positive for SF1, AE1/3 (patchy) and calretinin, and negative for GATA3, ER, PAX8, CD10 and EMA. Case B: at surgery the lump was fleshy, with some dead tissue, stuck to the front of the pelvis and clearly separate from the tube and ovary. The rapid test suggested FATWO among other possibilities. She had keyhole removal of the womb, both tubes and ovaries and the omentum, plus a sample of the pelvic lining. The final lab report showed a 9.5 cm FATWO. Stains were positive for WT-1, inhibin (in several areas), calretinin (in several areas) and SF-1 (patchy), and negative for STAT6 and CK7.

What happened

Both women recovered well and went home the same day. Both were referred back to their own gynaecologist for routine follow-up. No further treatment was given. The paper does not report how long they were followed up. Two cases are too few to tell us what will happen to others.

Why it matters

Case A suggests a FATWO can stay in the body for many years without causing trouble, and that it can twist (torsion) and cause sudden pain. The authors say FATWOs are generally benign and that, in most cases, complete removal by surgery is enough. They note there are no blood markers for FATWO, scans find it hard to tell it from other lumps, and there are no guidelines on follow-up. They also say chemotherapy has an unclear role for FATWOs that come back, and that more cases with follow-up are needed. They suggest that, because FATWO usually sits apart from the ovary, keeping the ovary could be argued for in some patients.

Checked line by line against the paper: 26 Oct 2026.

A Portuguese team describes a 39-year-old woman whose FATWO beside her right ovary was first watched, then grew and was removed, and they stress how hard FATWO is to diagnose and how unpredictable it can be.

The patient or patients

One healthy woman aged 39, who had had two pregnancies and two births, treated at a hospital in Vila Nova de Gaia, near Porto, Portugal. A scan found by chance a 51 mm lump beside her right ovary, which was thought to be a fibroid hanging from the womb or in the broad ligament. Her womb was also enlarged with fibroids. Her blood cancer markers were normal. As she was thinking about another pregnancy, doctors and she chose to watch it. Two years later she no longer wanted to keep her fertility. By then the lump was 115 x 66 mm on an internal ultrasound, with solid and fluid-filled parts and little blood flow. Her CA-125 was raised at 67.3 U/mL. The mixed solid and fluid-filled lump and the raised CA-125 raised concern about ovarian cancer.

What doctors did

Surgeons opened the tummy and found a 15 x 8 x 8 cm solid and fluid-filled mass. A quick microscope check during the operation (frozen section) favoured a fibrothecoma. They removed the right ovary and tube, the womb and the left tube. The paper does not list removal of the left ovary. The full lab report found mainly solid, tube-like and sieve-like patterns, with sheets of spindle or oval cells and fluid-filled spaces, and no significant variation in cell shape. Stains were positive for keratins (Cam5.2), calretinin, WT1, vimentin and inhibin (around the spaces), and negative for desmin, smooth muscle actin, EMA, CD10, PAX8 and keratin 5. The final diagnosis was FATWO. After talking it through with her, no further treatment was planned, because there are no agreed signs that predict how FATWO will behave.

What happened

She was clinically well 4 years after the operation. The paper does not mention the tumour coming back. This is a single case, so it can't tell us what will happen to others.

Why it matters

This case shows how FATWO can be mistaken for other things: on scans it looked like a fibroid, the raised CA-125 and mixed appearance raised worry about ovarian cancer, and during the operation it was taken for a fibrothecoma. The authors say FATWO is usually benign but almost one-fifth of cases behave more aggressively, sometimes spreading or coming back long after diagnosis. They say treatment is decided case by case, and that complete surgical removal is generally considered the most suitable treatment, and advise long-term follow-up. They warn that mistaking FATWO for a cancer, especially endometrioid adenocarcinoma of the ovary, is a common pitfall.

Checked line by line against the paper: 26 Oct 2026.

Pathologists in Hefei, China, describe a 29-year-old woman whose 3 cm FATWO on the end of her left fallopian tube was found by chance during a caesarean section and simply removed.

The patient or patients

One woman aged 29, admitted to hospital to have her baby at the Second People's Hospital of Anhui Province, Hefei, China. She had no symptoms from the tumour.

What doctors did

During her caesarean section in January 2019, surgeons noticed a growth at the fringed (fimbrial) end of the left fallopian tube. It looked grey-yellow, like a fatty lump (lipoma), with enlarged (varicose) blood vessels on the surface and a soft feel. They removed the lump on its own (simple excision). It measured 3.0 x 2.8 x 2.2 cm, had a complete capsule (outer covering) and was grey-white and fairly soft inside. Under the microscope the capsule was intact and the cells were short and spindle-shaped, packed closely in sheets, small tubes and many small cysts, with a complete basement membrane around the tubes. The cells looked bland, with no obvious abnormality and no obvious cell division. Stains: CK (partly +), Calretinin (+), α-inhibin (partly +), CD10 (focally +), GATA3 (-), EMA (-), Ki-67 (3%), WT-1 (+), PAX-8 (-). The local diagnosis was Wolffian adnexal tumour, with a note that it may have malignant potential and that an expert opinion was advised. An expert review at Peking Union Medical College Hospital agreed it was a Wolffian adnexal tumour, noting low proliferation and no prominent abnormality or cell division.

What happened

She had no radiotherapy or chemotherapy after the operation. At 6 months of follow-up she had recovered well. This is a single case, so it can't tell us what will happen to others.

Why it matters

This case shows FATWO can be found by chance in a young woman, during an unrelated operation, and can look like a simple fatty lump. In their discussion the authors summarise earlier reports: fewer than 90 cases worldwide, aged 15 to 83 (average 50); most cause no symptoms. Citing another paper, they say that when FATWO comes back or spreads it does so 13 to 96 months after surgery (average 48 months), mainly to the liver and lungs. They say the best treatment is removal of the womb and both tubes and ovaries, unless the woman is unmarried or is too old to cope with the operation. They say that when FATWO comes back, it is mostly in women who had only the tumour itself removed; radiotherapy and chemotherapy are usually not needed after surgery, and long-term follow-up is advised. For FATWO that comes back or spreads, they say treatment choices are limited and must be tailored; hormone treatment could be considered if the tumour is ER or PR positive, and a targeted tablet (a tyrosine kinase inhibitor) if it is CD117 positive, but this needs more research. They mention that CD56 has been reported as a possible marker to help tell harmful from harmless FATWOs.

Checked line by line against the paper: 26 Oct 2026.

A Chinese ultrasound team describes three women with small FATWOs, mostly found by chance, and suggests ultrasound features that may help doctors suspect FATWO before surgery.

The patient or patients

Three women treated at a women's hospital in Hangzhou, China. Case 1: aged 45, no symptoms; the lump was found on a routine check-up ultrasound in 2012. Case 2: aged 45, had known about a pelvic lump for 6 years and had mild low back pain for two months; seen in 2012. Case 3: aged 27, lump found by chance on ultrasound two months before admission in 2017. All three had normal blood tests, hormone levels and tumour markers (Case 2's markers included CA-125).

What doctors did

All three had ultrasound, plus CT (Cases 1 and 2) or MRI (Case 3). Case 1 had keyhole surgery: a 4 x 4 x 5 cm solid lump in the left mesosalpinx was removed with the left tube and ovary. A rapid test during surgery had suggested a sex cord tumour. Case 2 had open surgery: a 4 cm part-solid, part-cystic lump in the left mesosalpinx was removed with the left tube and ovary, and four fibroids were taken out of the womb. Case 3 had keyhole surgery: a 3 x 3 x 2 cm lump near the right tube was removed with the right tube and ovary. In the lab, all three were enclosed in a capsule and mostly solid, with no bleeding or dead tissue, few dividing cells (1 to 2 per 10 high-power fields) and no spread into blood vessels. Stains were positive for inhibin, calretinin, D2-40, WT1, AR, p53, CD10 and CD99, and negative for CK5/6, EMA, Vim and CD31. The Ki67 growth index was below 5%.

What happened

The paper says Cases 1 and 2 remained well 8 years after surgery, and Case 3 remained well at 30 months. It does not specifically say whether scans were done to look for the tumour coming back. This paper also reports survival figures, which we have left out of this summary. Three cases are too few to tell us what will happen to others.

Why it matters

The authors say there were no earlier reports focused on how FATWO looks on scans. On ultrasound, all three were well-defined, mostly solid lumps with moderate blood flow, sitting beside a normal-looking ovary that moved separately when the patient breathed. One had small packed cysts. The authors suggest these features, in the broad ligament area, may help doctors suspect FATWO before an operation. They also discuss telling FATWO apart from fibroids, which tend to show less blood flow.

Checked line by line against the paper: 26 Oct 2026.

Doctors describe a 16-year-old girl whose heavy periods led to scans that found a 6.2 cm FATWO, which was removed from the broad ligament.

Written from the abstract only (full paper not free).

The patient or patients

One girl aged 16 with heavy bleeding during her periods and no other obvious signs. Ultrasound showed a mass on the left ovary. A CT scan showed a solid mass that took up contrast, measuring 6.2 x 5 x 4.5 cm, in the left adnexa.

What doctors did

A mass in the broad ligament was removed. Fluid washings from the tummy showed no cancer cells. The microscope appearance and stains confirmed FATWO.

What happened

She recovered from the operation without problems, but she was then lost to follow-up, so later outcomes are not known. This is a single case, so it can't tell us what will happen to others.

Why it matters

The authors say fewer than 100 cases had been reported. They say it is hard to diagnose because it is rare, often causes no symptoms, can grow in different places and can look different under the microscope, especially when it appears to come from the ovary.

Checked line by line against the paper: 26 Oct 2026.

Doctors in Moscow describe a 45-year-old woman having surgery for early cervical cancer whose ovarian mass, first thought to be a cancer, turned out to be a FATWO judged to be apparently benign.

The patient or patients

One woman aged 45, treated at the P.A. Herzen Moscow Oncology Research Institute, Russia, for stage IB1 cervical cancer (an endocervical adenocarcinoma). Her tests before surgery found a mass on the left ovary. Ultrasound showed a 5.7 cm multi-chambered fluid mass with a 3.5 cm solid part and a strong blood supply, which the doctors read as a likely cancer. MRI showed a swollen left fallopian tube ending in a 4.1 x 3.6 x 4.7 cm cyst with a solid part of about 3 cm. Her blood markers were normal: CA-125 6 U/mL, HE4 29.1 pmol/L and SCC 2.2 ng/mL.

What doctors did

Because of the cervical cancer she had a nerve-sparing extended hysterectomy, with both ovaries and tubes removed. At the operation the left-side mass was up to 6 cm, bumpy and bluish-red. A quick microscope check during surgery wrongly called it an adenocarcinoma (a cancer), so the surgeons also removed most of the omentum. The full lab report found a 2.5 cm cyst at the edge of the left ovary containing a single smooth 1.7 cm nodule on a thin stalk. Under the microscope it had tube- and finger-like structures lined by cube-shaped cells, little abnormality, no dividing cells and no dead tissue. It was clearly different from the cervical cancer. Stains were negative for inhibin, vimentin, calretinin, chromogranin, CD-99, CD-10, WT-1 and oestrogen receptors, and positive for CK-7 and EMA, with p-53 weakly positive in some cells. The paper reports CD-56 was not expressed. The final diagnosis was a Wolffian duct cell tumour.

What happened

The authors regarded the tumour as apparently benign, because there was no dead tissue, no growth into the capsule and little or no cell division. They recommended regular monitoring. No follow-up results are given. This is a single case, so it can't tell us what will happen to others.

Why it matters

This case shows FATWO being found by chance while a woman was being checked for another cancer, which the authors say is common. Scans made it look like a cancer, and the quick test during surgery got it wrong, which led to extra surgery. The authors say scans cannot reliably tell FATWO from other tumours. They note that, in the earlier papers they reviewed, the tumour came back in about 5 to 10% of cases and 19 cases had spread to distant organs. They mention one earlier small study where a malignant FATWO stained positive for CD-56 and benign ones did not, but this is based on only three cases. They say there are no treatment guidelines, and the role of extra chemotherapy, radiotherapy or hormone treatment is unclear.

Checked line by line against the paper: 26 Oct 2026.

A US team describes a 47-year-old woman whose small Wolffian tumour (FATWO) was found by chance on the side wall of her pelvis during hernia surgery, which they believe is the first case reported in that place.

The patient or patients

One woman aged 47, treated at the University of Maryland Medical Center in the USA in 2017. She had several other health conditions, including a lung condition (COPD), asthma, diabetes and obesity. She was having an operation to repair a hernia in her tummy wall that had come back. She had no symptoms from the tumour.

What doctors did

During the hernia operation, surgeons noticed a lump on the right side wall of the pelvis. It looked like trapped fat and was completely separate from her right ovary and tube. They cut it out and sent it to the lab. The lump weighed 8 g and measured 3.5 x 2.5 x 2.3 cm. Under the microscope it had sheets of cells, gland-like shapes and tubules, with no worrying cell changes and no dividing cells seen. Stains were positive for inhibin, calretinin, pancytokeratin and CD10, and negative for PAX-8, CD34, actin, desmin, S100, EMA and HMB45. This supported a diagnosis of Wolffian tumour. No further treatment is described.

What happened

Her recovery was uneventful. About one month after surgery she had no symptoms and was healing well, and she was discharged from clinic to return if needed. No longer follow-up is reported. This is a single case, so it can't tell us what will happen to others.

Why it matters

The authors say this is the first reported Wolffian tumour on the pelvic side wall, separate from all the reproductive organs. They say it supports the World Health Organization name 'Wolffian tumour', dropping the word 'adnexal'. In their own search of earlier papers they counted 67 reported cases, 19 of them malignant, and say about one-fifth of Wolffian tumours are diagnosed as malignant overall. They add that some 'malignant' cases may actually have been other cancers that were wrongly identified, and that malignancy is decided by the tumour coming back or spreading, not by stains or tests. They encourage a wide range of stains to make the diagnosis.

Checked line by line against the paper: 26 Oct 2026.

A German team reviews what was known about FATWO in 2019 and describes a 33-year-old woman whose tumour was removed by keyhole surgery while keeping her fertility, after which she had a baby.

The patient or patients

One woman aged 33 from Germany, who had been trying for a baby without success; a lump beside her left ovary and tube was found on ultrasound. The review covers the roughly 80 cases described worldwide at the time, in women aged 15 to 81 (middle age 50).

What doctors did

For the new case: ultrasound, normal tumour marker blood tests (CA-125 and CEA), and an MRI scan, which showed a thin dark rim around the lump (a 'rim sign') that an earlier Japanese study had linked to FATWO. The lump was removed by keyhole surgery. Tests on the tumour included many stains and a gene test for c-KIT (no change found) and FOXL2 (no change found, which helped rule out a granulosa cell tumour). A CT scan of the chest and abdomen showed no spread. Because she wanted children, she then had only her left fallopian tube removed, which showed another tiny (1 mm) piece of tumour. She was advised to have close check-ups and further surgery once her family was complete. The review describes surgery (usually removal of the womb, both ovaries and tubes) as the main treatment, with a fertility-sparing approach used in some younger women.

What happened

The woman became pregnant naturally a few months later and had an uncomplicated birth in February 2018. Further surgery was again recommended, but she did not want it yet. The paper does not report the tumour coming back up to that point. The new case is a single case, so on its own it can't tell us what will happen to others. In the wider literature, the tumour came back or spread in about 10 to 20% of cases, especially to the lungs and liver. The middle time to it coming back was about 48 months, mostly between 13 and 96 months, and occasionally later. One collection of 21 cases found that women whose tumour was completely removed and who had no tumour spots elsewhere did not have it come back. Chemotherapy and radiotherapy after surgery were described in only a few cases. When the tumour came back, surgery was given first priority; of the chemotherapy tried, a platinum drug with paclitaxel seemed to work best. Hormone treatments did not stop the disease growing in the cases reported. Imatinib was tried in 3 women whose tumour showed the c-kit protein: in one, scans showed a response, a later operation found no visible tumour, and she had no sign of it coming back 10 months later; in another, the tumour grew after 4 months of imatinib but then shrank clearly after 10 cycles of carboplatin and paclitaxel; the third outcome was not reported.

Why it matters

It shows that fertility-sparing surgery is sometimes chosen for younger women, though the authors note the risk of the tumour coming back seems higher with this approach. It also points to an MRI sign that may help doctors suspect FATWO before surgery. For researchers, it adds a case where the c-KIT gene and protein were both tested and gathers early reports of imatinib and chemotherapy.

Checked line by line against the paper: 26 Oct 2026.

Reading the DNA of seven FATWO tumours found changes in KMT2D (meaning unclear), STK11 and ARID1B in some, but no single gene change that defines FATWO.

Written from the abstract only (full paper not free).

The patient or patients

8 patients with FATWO. Good-quality DNA could be obtained from 7. The abstract does not give ages, countries or how the tumours first showed up.

What doctors did

The tumours were tested with next-generation sequencing covering 300 cancer-related genes, to look for small gene changes, copy number changes and larger rearrangements. The aim was to see whether FATWO is similar at gene level to mesonephric carcinoma, another tumour thought to come from the same kind of leftover tissue lower in the genital tract.

What happened

New changes in the gene KMT2D were found in 4 of 7 tumours, but their importance is not known (variants of uncertain significance). STK11 changes were found in 2 of 7; one of these patients was already known to have Peutz-Jeghers syndrome. A change in ARID1B was found in 1 of 7. None had changes in KRAS, NRAS, TP53, PIK3CA, PTEN or DICER1. There were few copy number changes; one tumour had extra copies of CCND1. No larger rearrangements were found. The abstract does not report treatment or follow-up.

Why it matters

It suggests FATWO is different at gene level from tumours it can be confused with: it lacked the KRAS/NRAS changes typical of mesonephric carcinoma and the DICER1 changes typical of Sertoli-Leydig cell tumour. The authors say the gene change that defines FATWO has not yet been found, so more research is needed. The STK11 finding, including one patient with Peutz-Jeghers syndrome, is relevant to later work on STK11 in these tumours.

Checked line by line against the paper: 26 Oct 2026.

A Canadian team describes a 29-year-old woman with a 7.2 cm FATWO beside the vagina, which a small biopsy first suggested was a different, harmless tumour (vaginal spindle cell epithelioma).

The patient or patients

One woman aged 29 who had had two children. She had irregular vaginal bleeding for three weeks. Her family doctor found a lump wearing through into the vagina. MRI showed a 7.2 cm lump low in the left pelvis, separate from the cervix and womb, with signs of bleeding inside it and no dead areas.

What doctors did

A biopsy showed mainly spindle-shaped cells with some gland-like cells, mild cell changes and many apoptotic cells (cells that had broken down naturally). Stains were positive for many markers including CK7, CD10, CD56, p16 and vimentin; partly positive for desmin, calretinin and actin; and negative for ER and PR. The Ki67 growth index was 15 to 20%. This suggested vaginal spindle cell epithelioma, but because the sample was in pieces and the growth index was raised, complete removal was advised. At surgery the lump was confirmed to be beside the vagina and was removed without complication. In the lab, the whole tumour was well defined, deep in the vaginal wall, and mostly had the sieve-like pattern typical of FATWO, which had been hard to see on the small biopsy. Cell changes were minimal, with 4 dividing cells per 10 high-power fields. Stains were positive for AE1/AE1 (as printed; probably AE1/AE3), CAM 5.2, CK7, 34bE12, MOC31, p16, CD99, CD56 and CD57; partly positive for EMA, CD10 and calretinin; and negative for vimentin, myogenin, desmin, AFP, Bcl-2, inhibin, WT-1, CEA and CD117/c-kit. A gene test (FISH for the SS18 gene) ruled out synovial sarcoma. The diagnosis was FATWO.

What happened

No extra treatment (such as chemotherapy or radiotherapy) was given. There was no sign of it coming back or spreading at 8 months. This is a single case, so it can't tell us what will happen to others.

Why it matters

FATWO beside the vagina is very rare. The authors warn that a small biopsy can miss the typical sieve-like pattern and show mostly spindle cells, which can be mistaken for vaginal spindle cell epithelioma. This matters because that tumour is benign, whereas the authors regard FATWO as potentially cancerous. They advise caution about making that diagnosis on a biopsy with a high Ki67, and say the diagnosis should rest on the whole clinical and lab picture rather than stains alone. The discussion also reviews earlier treatments reported for FATWOs that came back, including imatinib and hormone treatment, noting the evidence is limited.

Checked line by line against the paper: 26 Oct 2026.

An Indian team describes a 48-year-old woman whose 20 cm lump, thought on scans to be an ovarian cyst, turned out to be a FATWO of the broad ligament, and reports gene tests on the tumour.

The patient or patients

One woman aged 48, around the menopause. For about a year she had on-and-off pain on the left side of the tummy, eased by painkillers, plus weight loss and about five months of poor appetite. Examination showed mild paleness and a large, mildly tender lump in the pelvis reaching up to the belly button. Ultrasound and MRI suggested a left ovarian cyst (mucinous cystadenoma) with some solid parts, and a bulky womb with fibroids. CA-125 was mildly raised.

What doctors did

She had keyhole surgery to remove the womb, both tubes and ovaries, and the cyst. The tubes and ovaries looked normal. The lump was a 20 x 16 x 8 cm complex cyst coming from the left broad ligament, with fluid-filled and blood-filled spaces and grey solid areas, without bleeding into the tissue or dead tissue. The lab confirmed FATWO with no abnormal-looking cells. The authors say 15 stains were used, but name 14: strongly positive for ER, PR, WT-1, CD56, desmin and SMA; moderately positive for CK, Melan A and calretinin; negative for EMA, S-100, CK7, inhibin and CD10. Gene testing found a change in exon 12 of the PDGFRA gene, none in PDGFRA exons 14 or 18, and none in KIT exons 8 or 11.

What happened

She recovered without problems and has had regular check-ups. An ultrasound of the tummy and pelvis 45 days after the operation was normal. The paper does not report longer follow-up. This is a single case, so it can't tell us what will happen to others.

Why it matters

The authors describe this as the third reported case in India and the first from India with gene testing. They suggest gene testing could be an extra tool to help diagnose FATWO. They say complete removal (womb, both tubes and ovaries) is considered the most effective way to prevent the tumour coming back, that there is no agreed plan for tests or follow-up, and that long-term follow-up and more research are needed.

Checked line by line against the paper: 26 Oct 2026.

Doctors describe a 50-year-old woman, who had already had her womb and left ovary removed, who developed a 14 cm FATWO in her right ovary.

Written from the abstract only (full paper not free).

The patient or patients

One woman aged 50 with 3 weeks of tummy pain and swelling. She had previously had a total hysterectomy with her left ovary and tube removed. Ultrasound through the vagina and a CT scan showed a 14 x 10 x 8 cm tumour of the right ovary. Her CA-125 was normal.

What doctors did

She had an open operation to explore the tummy and the tumour was examined. Under the microscope the cells were only slightly abnormal and very few were dividing. Stains were strongly positive for pancytokeratin, cytokeratin 7, vimentin and calretinin; partly positive for inhibin and CD10; and negative for oestrogen and progesterone receptors, chromogranin, CEA, EMA, CD99 and CD117.

What happened

The abstract does not report how she did after surgery. This is a single case, so it can't tell us what will happen to others.

Why it matters

The authors say diagnosis before surgery is very difficult. Because of its malignant potential, they say patients should be properly checked for possible recurrence after the first operation.

Checked line by line against the paper: 26 Oct 2026.

Doctors in Nanjing, China, describe a 34-year-old woman with a pelvic lump that turned out to be a FATWO growing from the mesosalpinx, the tissue that holds the fallopian tube.

Written from the abstract only (full paper not free).

The patient or patients

One woman aged 34 who had never given birth (nulliparous), referred to a hospital in Nanjing, China, after a pelvic mass was recently found.

What doctors did

The diagnosis of FATWO was confirmed by examining the tumour under the microscope and with stains. The tumour arose from the mesosalpinx.

What happened

The abstract does not describe the treatment or what happened afterwards. This is a single case, so it can't tell us what will happen to others.

Why it matters

It adds one more case of FATWO in a younger woman, at a less common site (the mesosalpinx). The authors note that fewer than 90 cases had been reported worldwide at the time, and they also review earlier reports.

Checked line by line against the paper: 26 Oct 2026.

Doctors describe a 50-year-old woman with a malignant FATWO in both ovaries that had grown into the fallopian tube and onto the surface of the womb, and explain why it was hard to diagnose.

Written from the abstract only (full paper not free).

The patient or patients

One woman aged 50. The authors are from hospitals in Jinan, China, and in Arizona and Texas, USA. The tumour involved both ovaries, invaded the fallopian tube on the same side, and extended to the outer surface of the womb (uterine serosa).

What doctors did

At first the microscope findings caused significant confusion. The pathologists considered several other diagnoses: ovarian endometrioid carcinoma, Sertoli cell tumour, and spread from a cancer outside the reproductive organs. After careful examination and many stains, they reached the diagnosis of FATWO. They also reviewed earlier published cases, including malignant ones.

What happened

The abstract does not describe treatment or what happened afterwards. This is a single case, so it can't tell us what will happen to others.

Why it matters

The authors note that most FATWOs behave in a benign way, but occasional cases show malignant potential. This case is unusual because it involved both ovaries and had grown into nearby organs. It also shows how easily FATWO can be mistaken for other tumours, and why many stains may be needed.

Checked line by line against the paper: 26 Oct 2026.

An Indian team reports a 70-year-old woman, whose womb had already been removed, with a lump that was thought to be ovarian cancer but turned out to be a benign Wolffian adnexal tumour.

Written from the abstract only (full text could not be opened).

The patient or patients

One woman aged 70 who had previously had her womb removed (hysterectomy). She came with a lump in her tummy and was first thought to have a cancerous ovarian tumour.

What doctors did

She had a staging operation (open surgery to remove and check for spread). A solid lump coming from the left adnexa was removed, along with the right tube and ovary and the lymph nodes in the pelvis.

What happened

The lab report was 'benign Wolffian adnexal tumour'. The abstract does not report follow-up. This is a single case, so it can't tell us what will happen to others.

Why it matters

It shows FATWO can be mistaken for ovarian cancer before surgery. The authors say most FATWOs are benign but some can behave in a cancerous way, and that diagnosis often depends on ruling out other tumours. They say removing the womb and both tubes and ovaries is considered the recommended treatment, and that the role of extra radiotherapy or chemotherapy is still debated.

Checked line by line against the paper: 26 Oct 2026.

Japanese doctors describe a 37-year-old woman whose FATWO came back after 15 months; imatinib held it steady for about 4 months, and later paclitaxel with carboplatin shrank it almost completely after 10 rounds.

The patient or patients

One woman aged 37, treated in Okinawa, Japan. She had severe lower tummy pain. Scans showed a 7 cm twisted, part-solid, part-fluid mass on the left side with some fluid in the tummy. Her CA-125 and other blood markers were normal (CA-125 35 IU/mL).

What doctors did

In 2013 she had an operation to remove the left ovary and tube, sample lymph glands and take a piece of the omentum. The tumour came from the end of the left fallopian tube and reached the broad ligament. Tiny spots (under 5 mm) were on the left ovary, and tumour cells were found in the tummy fluid. Stains confirmed FATWO. No extra treatment was given; she had CT scans every 6 months. When it came back in July 2014, surgeons removed the womb, the right ovary and tube and the spread tumour, but could not remove all of it. The tumour cells now stained positive for KIT. Gene tests of c-KIT and PDGFR found no changes. She took imatinib (Glivec) 400 mg a day for 6 months. When the tumour grew, she had another operation in June 2015 that again could not remove everything. She then had paclitaxel with carboplatin every 3 weeks.

What happened

The tumour came back as many spots on the tummy lining 15 months after the first operation. Six weeks after the second operation, the remaining spots had grown. On imatinib, the tumours stayed steady for about 4 months and then grew. After the third operation the spots grew again. With paclitaxel and carboplatin, the tumours shrank partly after 6 rounds and kept shrinking; after 10 rounds the spots in the pelvis and on the right side of the tummy could no longer be seen on CT (an almost complete response). She was still having this chemotherapy in June 2016, when the report ends. The authors say she needs continued follow-up. This is a single case, so it can't tell us what will happen to others.

Why it matters

It is one of the few reports where a FATWO that came back clearly shrank with chemotherapy, in this case paclitaxel with carboplatin after imatinib had stopped working. It also adds to the small number of FATWO cases that tested positive for KIT without a KIT gene change. The authors stress that surgery to remove as much tumour as possible remains the main treatment, and that the role of chemotherapy and targeted drugs is still unknown.

Checked line by line against the paper: 26 Oct 2026.

Italian researchers tested the genes of three FATWOs with next-generation sequencing and found different gene changes in each tumour, with no shared pathway.

Written from the abstract only (full paper not free).

The patient or patients

Three FATWOs from the archives of the authors' institution in Sassari, Italy. The abstract gives no patient details.

What doctors did

The team re-examined the tumours under the microscope and used next-generation sequencing, a broad gene-testing method, to look for gene changes (mutations).

What happened

Each tumour had missense mutations in different genes belonging to different growth pathways: the first had CTNNB1 and MET mutations; the second had a PIK3CA mutation; the third had BRAF and CDKN2A mutations. Two further variants, in the KDR and TP53 genes, were found whose effect on the protein is unknown. No common pathway was involved across the three.

Why it matters

Little is known about what drives FATWO at the gene level. This small pilot study suggests FATWOs may differ from each other genetically (genetic heterogeneity). The authors say larger studies are needed to confirm this. No STK11 change is mentioned in the abstract.

Checked line by line against the paper: 26 Oct 2026.

An Italian ultrasound team describes a 70-year-old woman with a 21 cm Wolffian tumour growing in the space behind the tummy lining (the retroperitoneum), and what it looked like on ultrasound.

The patient or patients

One woman aged 70, referred to a centre in Rome with a lump in the pelvis and a swollen tummy. She had earlier had her womb, both tubes and both ovaries removed for fibroids, and her ovaries had been normal in the lab. Ultrasound showed a solid lump of about 16 cm in the pelvis with many fluid-filled spaces and little blood flow. A CT scan showed lung nodules thought to be spread (metastases). CA-125 and CA19-9 were normal.

What doctors did

Doctors suspected a cancer and thought it might come from the retroperitoneum, as her womb and ovaries had already been removed. At open surgery, a 21 cm lump behind the tummy lining, pushing on the bladder, bowel and the large blood vessels on the left of the pelvis, was removed. It had not grown into nearby organs. In the lab the tumour was mostly solid with cystic areas, with areas of bleeding and no dead tissue. Stains were positive for CAM 5.2, CK AE1/AE3, CD10, vimentin and the oestrogen receptor, and negative for α-inhibin, EMA, calretinin, CK7, CD99, CD56, chromogranin and synaptophysin. Because the tumour had oestrogen receptors and there was spread to the lungs, she was given tamoxifen, a hormone tablet, after surgery.

What happened

The report does not say how she responded to tamoxifen or give any follow-up. This is a single case, so it can't tell us what will happen to others.

Why it matters

The authors say this is the first description of what a Wolffian tumour looks like on ultrasound: a very large solid lump with a regular edge, fluid-filled spaces and little blood flow. It also shows that these tumours can arise outside the broad ligament and ovaries, here in the retroperitoneum, and that hormone treatment was tried because the tumour had oestrogen receptors.

Checked line by line against the paper: 26 Oct 2026.

Doctors in Shanghai, China describe a 53-year-old woman whose large Wolffian adnexal tumour came back two years after surgery as many lumps in the tummy and pelvis, and who became very unwell despite a second operation and chemotherapy.

Written from the abstract only (full text could not be opened).

The patient or patients

One woman aged 53, treated at Shanghai Jiao Tong University Affiliated Sixth People's Hospital, China. She had a swollen tummy. Ultrasound showed a mixed-looking mass around the womb measuring 130 x 93 x 116 mm (about 13 cm), and fluid in the tummy. Her CA-125 and CA19-9 blood tests were raised.

What doctors did

First operation: removal of the womb, both ovaries and the tumour. Tests on the tissue showed a Wolffian adnexal tumour. Two years later, ultrasound and CT scans found many lumps in the tummy and pelvis. Second operation: open surgery found nodules in the omentum, the mesentery (the tissue that holds the bowel in place) and the lining of the pelvis. Surgeons removed the pelvic lumps and part of the omentum. Stains were positive for inhibin A, calretinin, oestrogen receptor, progesterone receptor, CD99 and Pax2. She then had chemotherapy (the abstract does not name the medicines).

What happened

The tumour came back two years after the first operation. Despite chemotherapy after the second operation, she became very unwell 2 months after that surgery. This paper also reports survival figures, which we have left out of this summary. This is a single case, so it can't tell us what will happen to others.

Why it matters

The authors say this case further suggests that Wolffian adnexal tumours can behave in a malignant way, and that close follow-up is necessary. Her CA-125 and CA19-9 blood tests were raised when she first became unwell. The abstract does not mention gene testing, so it is not known whether this tumour had an STK11 change; later papers treat STK11-changed tumours as a separate type.

Checked line by line against the paper: 26 Oct 2026.

A Chinese team describes a 73-year-old woman with a 26 cm FATWO from her left ovary, which they believe is the largest benign one reported, and review 18 published FATWOs of the ovary.

The patient or patients

One woman aged 73, treated in Shanghai, China, in 2015. She had had fibroids removed from her womb 20 years earlier. She had tummy pain and bloating for two weeks, and a large lump could be felt in her tummy. Blood tumour markers, including CA-125, were normal. CT and MRI scans showed a large lobed mass, but where it came from was unclear. The paper also lists 18 published women with FATWO of the ovary (including her), aged 27 to 87.

What doctors did

Because her pain and bloating were not improving, surgeons opened the tummy. The tumour filled her whole tummy and pelvis and measured about 26 x 24 x 15 cm. It was well wrapped in a capsule and partly stuck to nearby tissue. It came from the left ovary. There was no fluid in the tummy and no enlarged lymph glands. A quick microscope check during the operation (frozen section) showed no cancer, so only the tumour was removed (simple tumour resection). Under the microscope there were solid, sieve-like and tightly packed patterns, with some bleeding and dead tissue in the tumour. Stains were positive for vimentin, CD99 and pan-cytokeratin, partly positive for calretinin, alpha-inhibin and CD56, and negative for chromogranin, EMA, CD10, CD34, synaptophysin and S-100. Ki-67 was 3%. No further treatment was given.

What happened

She went home 9 days after surgery. About 6 months later there was no sign of the tumour coming back or spreading, and she was having regular check-ups. In the review table of 18 ovarian FATWOs, four are marked as having spread beyond the ovary, one woman had the tumour spread to the lung 8 years later, and four were lost to follow-up. This paper also reports survival figures, which we have left out of this summary. This is a single case, so it can't tell us what will happen to others.

Why it matters

The authors say this is the largest benign FATWO reported. From earlier papers they report that about one-fifth of cases had an adverse outcome, with the liver and lung as the main places of spread, and that most returns happened in women who had only the tumour removed. The authors state that of the 18 ovarian cases, 16 had both ovaries and tubes removed (with or without the womb) and 2 had only the tumour removed (but see Points we could not confirm). The authors suggest removing the womb with both ovaries and tubes unless a woman is unmarried or too old to cope with the surgery, and advise long-term follow-up. They say chemotherapy or radiotherapy is controversial and usually not effective, and that an earlier study suggested a targeted tablet (Gleevec, STI 571, a tyrosine kinase inhibitor) for tumours that come back or spread after surgery, but more study is needed. They also mention an earlier report that CD56 might help tell malignant from benign FATWO, which still needs checking.

Checked line by line against the paper: 26 Oct 2026.

A Korean team describes a 52-year-old woman with a cancerous FATWO whose tumour showed MGMT methylation, and which came back in the pelvis 9 months after surgery and grew despite chemotherapy.

The patient or patients

One woman aged 52, Korean, with mild pelvic pain for a month. She was referred with a lump near the right ovary. A CT scan showed an 8 cm solid lump in the area beside the left ovary at the back wall of the womb, thought possibly to be a fibroid or ovarian tumour. CA19-9 (5.92 U/mL) and CA-125 (12.38 U/mL) were normal.

What doctors did

A keyhole look (pelviscopy) found an 8 cm solid and papillary lump from the ovary's root to the area beside it. A rapid test during surgery showed a cancer with many dividing cells. She then had full staging surgery: removal of the womb, both tubes and ovaries, and the omentum, fluid washings, and removal of lymph nodes in the pelvis. Camera tests of the stomach and bowel were done during surgery to rule out spread from elsewhere. A PET-CT scan afterwards showed no distant spread. The lab confirmed a cancerous FATWO in the left ovary and tube, with no spread to lymph nodes. Electron microscopy favoured FATWO over mesothelioma. Stains were partly positive for D2-40, calretinin, CK, CD10, vimentin, CD56, CK7 and mucicarmine, and negative for CK 5/6, ER, EMA, HMP45, chromogranin, synaptophysin and CK20. Ki 67 was 20 to 30%. Blood tests found no BRCA1 or BRCA2 changes. A test on MGMT gene methylation was positive.

What happened

She had CT scans every 3 months. After 9 months, a 2.5 cm nodule was found on the right side low in the pelvis (cul-de-sac), confirmed by PET-CT as the tumour coming back. She had three cycles of paclitaxel and carboplatin chemotherapy. After this, the lump grew to 2.8 cm, and new spread appeared on the left side of the cul-de-sac and at the tip of the liver. More surgery and chemotherapy were planned, but she did not return for follow-up, so later outcome is not known. This is a single case, so it can't tell us what will happen to others.

Why it matters

The authors say this is the first FATWO case in Korea tested for MGMT methylation. They suggest switching off the MGMT gene in this way may have contributed to the tumour developing, but say more studies are needed. They note that, of 80 reported cases, 21 had come back or spread, most often to the liver; that there is no established chemotherapy for FATWO; that paclitaxel and carboplatin is the most used combination; and that in this case the tumour grew during it. They state that high numbers of dividing cells, abnormal cells and dead tissue usually go with aggressive behaviour.

Checked line by line against the paper: 26 Oct 2026.

A German article in a pathology journal, from Tübingen, describes what FATWO looks like under the microscope, which stains it usually shows, and which other tumours it can be mistaken for.

Written from the abstract only (full paper not free).

The patient or patients

The abstract does not describe any individual patient. It is a general description of the tumour type.

What doctors did

The authors describe FATWO's usual features under the microscope and its usual staining pattern, and list the tumours it can be confused with.

What happened

The authors say FATWO usually grows in the broad ligament or the mesosalpinx. Under the microscope it can look very different from one tumour to another, and even within one tumour (solid, small tubes, sieve-like and fluid-filled patterns). The cells usually look fairly ordinary and divide less often. They say FATWO generally behaves in a benign way, but rare cases turn malignant, so careful examination and follow-up checks are needed. Tumours it can be mistaken for include Sertoli-Leydig cell tumours, endometrioid cancer that has spread, and a FATWO-like form of endometrioid cancer of the fallopian tube. FATWOs stain for pancytokeratin, CD10, vimentin, calretinin and inhibin A. A minority stain for oestrogen and progesterone receptors. EMA is not found.

Why it matters

It gives a compact list of the stains pathologists use to confirm FATWO and rule out look-alike tumours. The negative EMA stain is one of the distinguishing points mentioned.

Checked line by line against the paper: 26 Oct 2026.

A US lab study tested 8 FATWOs and several look-alike tumours with a set of stains, and found that PAX-8 and SF-1 can help pathologists tell FATWO apart from endometrioid cancer and Sertoli cell tumours.

Written from the abstract only (full paper not free).

The patient or patients

Tissue from 8 FATWOs found by a database search, compared with 18 endometrioid cancers of the ovary, tube or nearby tissue, 8 Sertoli-Leydig and Sertoli cell tumours of the ovary, and 11 samples containing the rete ovarii. No individual patients are described.

What doctors did

The team stained the tissue samples for PAX-8, PAX-2 and GATA-3 (stains linked to Wolffian tissue) and SF-1 (a stain linked to sex-cord stromal tumours).

What happened

All 8 FATWOs were negative for PAX-8, PAX-2, GATA-3 and SF-1. All the endometrioid cancers were positive for PAX-8, and 57% were positive for PAX-2. All but one of the Sertoli-Leydig and Sertoli cell tumours were positive for SF-1. The rete ovarii was positive for PAX-8, weakly positive for SF-1, and negative for PAX-2 and GATA-3.

Why it matters

FATWO can look very like endometrioid cancer or Sertoli cell tumours. The authors suggest PAX-8 helps separate FATWO from endometrioid cancer, and SF-1 helps separate it from Sertoli cell tumours. They say their results do not support the idea that FATWO comes from Mullerian tissue, sex-cord stromal tissue or the rete ovarii. They find it curious that FATWO does not show Wolffian markers, and suggest it may come from a distinctive part of the Wolffian duct. This is a small study of 8 tumours.

Checked line by line against the paper: 26 Oct 2026.

Doctors in Japan describe two women with a Wolffian tumour whose MRI scans showed a dark rim round the tumour, which matched a layer of smooth muscle seen under the microscope.

Written from the abstract only (full paper not free).

The patient or patients

Two women. Case 1: aged 61, with a swollen left adnexa. Case 2: aged 40, with lower tummy pain.

What doctors did

Both had MRI scans before surgery. Case 1's scan showed a 4.4 cm solid mass in the pelvis; case 2's showed a 6.0 cm solid mass. Both tumours were examined under the microscope (the abstract says case 2's tumour was removed; it does not say what operation case 1 had), including stains for smooth muscle.

What happened

In both women, the T2 MRI showed a rim of low signal (a dark rim) round the tumour. Under the microscope, both tumours were made of cube-shaped cells with ordinary-looking nuclei packed in small tubes, and both were diagnosed as Wolffian tumours. The rim was made of spindle-shaped cells that stained for alpha-smooth muscle actin and desmin. The authors say these are the same as the smooth muscle cells that surround leftovers of the mesonephric duct. The abstract does not report follow-up.

Why it matters

FATWO is hard to recognise before surgery. The authors suggest that this dark rim on MRI might help doctors make an accurate diagnosis before an operation. This is based on two cases only.

Checked line by line against the paper: 26 Oct 2026.

A short conference report describes a 40-year-old woman with tummy pain and fever, operated on for an abscess, whose lab results unexpectedly showed a FATWO of the left broad ligament.

The patient or patients

One woman aged 40 who had never given birth and had a history of infertility and irregular periods. She had poorly controlled diabetes for 5 years. She had sudden tummy pain and fever for 2 days, with tenderness across the tummy, vaginal discharge and an unhealthy-looking cervix. A tender lump of about 8 x 6 cm was felt on the left. CA-125 was 35.60 IU/L, CEA 3.46 and beta-HCG 2.29, all described as normal. MRI showed a 9 x 8 cm part-solid, part-fluid lump on the left, a 6 x 7 cm cyst with bleeding on the right, a swollen fluid-filled tube, and a lump to the left of the womb thought to be a broad ligament fibroid.

What doctors did

She was started on antibiotics by injection for a suspected infection. Because of the sudden pain, keyhole surgery was done. It found abscesses on both ovaries and a solid lump in the left broad ligament, thought to be a fibroid. The surgeons drained the abscess, removed the left tube and ovary and the right tube, and freed scar tissue. The lab report showed FATWO, probably from the left broad ligament, positive for vimentin and CD10. She then had a radical hysterectomy with removal of the omentum and appendix because of the FATWO.

What happened

The report does not give the results of the second operation or any follow-up. This is a single case, so it can't tell us what will happen to others.

Why it matters

It shows FATWO can be found by chance when surgery is done for something else, here an infection, and that it can look like a fibroid at surgery. The authors note that diagnosing FATWO before surgery is very difficult because it is rare and little has been written about it, and that, although usually benign, some cases have spread or come back even after a long time.

Checked line by line against the paper: 26 Oct 2026.

A pathology report describes a FATWO with an unusual mix of two cell types, which tested positive for c-kit, a protein that some targeted tablets act on.

Written from the abstract only (full text could not be opened).

The patient or patients

The abstract describes one case but gives no details about the patient.

What doctors did

The tumour was examined in the lab. It grew in solid sheets with two parts: rounder (epithelioid) cells and long, thin (spindle) cells. The tumour cells were diffusely positive for oestrogen and progesterone receptors (ER and PR). The rounder cells were positive for AE1/3, CK-7 and CAM 5.2; the spindle cells were positive for vimentin and CD10. The tumour cells were negative for inhibin, CK20, P53, CA125, CD99, calretinin and CK5/6. They were positive for c-kit.

What happened

The abstract does not report treatment or follow-up. This is a single case, so it can't tell us what will happen to others.

Why it matters

The authors say the c-kit result gives extra support for the idea that tablets called tyrosine kinase inhibitors might be tried for FATWO. But they stress that it is not known how often FATWO is c-kit positive, or whether this means such treatment would work for FATWOs that come back or spread, and say this needs more study.

Checked line by line against the paper: 26 Oct 2026.

Pathologists at Temple University Hospital, USA, describe a 29-year-old woman with a widely spread broad ligament tumour that they thought was most likely a malignant FATWO, though a granulosa cell tumour could not be fully ruled out.

Written from the abstract only (full paper not free).

The patient or patients

One woman aged 29 with tummy pain and fever. A CT scan showed widespread tumour deposits in the pelvis and tummy lining. The main tumour was a 9.3 cm, mostly cystic mass in the right broad ligament, with deposits on the ovaries, womb, appendix, omentum and liver. It was stage IIIC.

What doctors did

She had chemotherapy called modified BEP before surgery, which had no clear effect. She then had removal of the womb, both ovaries and tubes, and as much tumour as possible. Under the microscope the tumour had small and large cysts, cords and structures like those seen in granulosa cell tumours, grooved nuclei, and up to 5 dividing cells per 10 high-power fields in places. Stains were diffusely positive for AE1/AE3, ER and vimentin, partly positive for inhibin and CEA, and negative for EMA, melan-A, AFP and FOXL2. A gene test found no FOXL2 mutation.

What happened

Later CT scans showed widespread tumour deposits in the pelvis and tummy. This paper also reports survival figures, which we have left out of this summary. This is a single case, so it can't tell us what will happen to others.

Why it matters

The authors leaned towards malignant FATWO because the FOXL2 stain and gene test were both negative; they say about 95% of adult granulosa cell tumours carry the FOXL2 mutation. But they could not completely rule out a granulosa cell tumour outside the ovary. The case shows how hard it can be to tell these two tumours apart.

Checked line by line against the paper: 26 Oct 2026.

Japanese doctors describe a 30-year-old woman whose FATWO had already spread as small deposits in the pelvis when first found, grew back within 4 months, and did not respond well to several chemotherapy and hormone treatments; they suggest tumours with such deposits at first surgery may come back early.

The patient or patients

One woman aged 30 in Japan, who had never been pregnant. She had no symptoms. In September 2008 a lump on her right ovary was found by chance at a routine smear test and pelvic examination, then seen on ultrasound and MRI. Blood tests: CA-125 31.8 U/ml, CA 19-9 6.8 U/ml, CEA 0.6 ng/ml, AFP 4.4 ng/ml. The paper also reviews 21 earlier published women with FATWO that came back or spread.

What doctors did

First operation: open surgery found a 5 cm lumpy tumour hanging from the right fallopian tube on a short stalk, with small tumour deposits on the surface of the pouch of Douglas (the space behind the womb). Surgeons removed the right ovary and tube and the tumour, and scraped out 17 deposits measuring 3 to 10 mm. The tumour had a capsule and came away easily. Fluid washings showed a few abnormal cells. Under the microscope the tumour was mostly solid with many small tubes and a sieve-like pattern, with many dividing cells in the solid parts and no bleeding or dead tissue. Stains: calretinin, inhibin, CD10 and vimentin were positive, desmin and CD34 positive in places, c-kit negative. Chemotherapy with paclitaxel and carboplatin was started, but she was allergic to paclitaxel, so she had 3 cycles of carboplatin alone. Second operation (6 months after the first): removal of the womb, both ovaries and the omentum, removal of tumour deposits, and lymph node samples. Extra stains on this tumour: CA125, calretinin, inhibin, CD10, oestrogen receptor, progesterone receptor and androgen receptor positive; HER2 negative. Later treatments, in order: medroxyprogesterone acetate (a hormone tablet) 400 mg a day for 3 months; removal of a bleeding lump at the vaginal opening under local anaesthetic; pegylated liposomal doxorubicin every 4 weeks for 3 cycles; irinotecan for 3 cycles; gemcitabine for 8 cycles. No gene testing is reported.

What happened

Despite the carboplatin, an MRI 4 months after the first operation showed the disease had grown. At the second operation there were many 2 to 3 cm deposits on the outside of the bowel, the omentum and the left ovary, and the tumour had grown back in the pouch of Douglas, although all deposits had been removed there at the first operation. The lymph nodes were clear. The returned tumour had more varied cell shapes than the first. The tumour kept growing on the hormone tablet, with a 2 cm lump by the left iliopsoas muscle (a muscle at the back of the pelvis) and a 2 cm lump in the front wall of the vagina. Pegylated liposomal doxorubicin was stopped after 3 cycles because of a serious lung inflammation side effect (interstitial pneumonia); at that point the MRI showed the disease was stable. Irinotecan did not work and caused sickness. Gemcitabine caused no side effects, but after 8 cycles MRI showed many lumps in the tummy, including on the surface of the liver. The authors say she had a poor response to chemotherapy and hormone treatment. This paper also reports survival figures, which we have left out of this summary. This is a single case, so it can't tell us what will happen to others.

Why it matters

The authors looked at earlier published cases and found that 3 of 8 women who had tumour deposits at their first operation had the tumour come back or spread within 1 year, while none of the women without deposits who had all the tumour removed had it come back within 1 year. They suggest that women with deposits or tumour left behind are at risk of early return, and that such tumours behave more aggressively than 'low malignant potential' suggests. They conclude that there are no recommendations for treatment after surgery, that surgery to remove as much tumour as possible appears to be the treatment of choice, and that other treatments remain experimental. Hormone treatment did not work here even though the tumour was positive for hormone receptors, and the tumour was c-kit negative (the paper notes imatinib was reported to delay recurrence in 2 c-kit-positive patients in an earlier report). No gene testing was done, so it is not known whether this tumour had an STK11 change; later papers treat STK11-changed tumours as a separate type.

Checked line by line against the paper: 26 Oct 2026.

An Indian pathology team reports a FATWO of the broad ligament in a 70-year-old woman, confirmed by stain tests, with cell features that the authors say may raise the chance of it coming back or spreading.

Written from the abstract only (full text could not be opened).

The patient or patients

One woman aged 70. The tumour grew from the broad ligament.

What doctors did

The diagnosis was confirmed with stain tests (immunohistochemistry). Under the microscope the tumour was very cellular, with cells varying in size and shape and abnormal-looking nuclei.

What happened

The abstract does not describe treatment or follow-up. This is a single case, so it can't tell us what will happen to others.

Why it matters

The authors say most FATWOs behave in a benign way, but that features like those seen here (many cells, variation in cell shape and abnormal nuclei) may increase the rate of coming back and spreading. They therefore recommend close follow-up for FATWO.

Checked line by line against the paper: 26 Oct 2026.

Doctors describe a 69-year-old woman with a malignant FATWO that stained for CD56, which came back one year after surgery, and suggest CD56 might help tell malignant FATWOs from benign ones.

Written from the abstract only (full paper not free).

The patient or patients

One woman aged 69. The abstract does not describe her symptoms. The authors also tested two benign FATWOs from their own hospital.

What doctors did

She had surgery (the type is not given in the abstract). The tumour was examined under the microscope and with a panel of stains.

What happened

The tumour was mostly solid, made of closely packed cells in thin branching tubes. Cells were dividing fairly often in the active areas (5 to 7 dividing cells per 10 high-power fields). The cells were strongly positive for glutathione S-transferase pi, and positive for calretinin, vimentin, c-Kit, CD99 and CD56, with partial neuron-specific enolase. They were negative for inhibin alpha, oestrogen receptors, progesterone receptors, BCL-2 and S100. It was diagnosed as malignant FATWO. The tumour came back one year after her first operation. The two benign FATWOs at the same hospital were negative for CD56. This is a single case, so it can't tell us what will happen to others.

Why it matters

The authors say only 14 malignant FATWOs had been reported worldwide at the time. They suggest CD56 might be a marker that helps tell malignant FATWOs from benign ones. This is based on one malignant and two benign tumours, so it is an early suggestion only.

Checked line by line against the paper: 26 Oct 2026.

A Turkish team describes a 51-year-old woman whose small FATWO grew in her right ovary, was removed by surgery with no further treatment, and showed no sign of coming back one year later.

The patient or patients

One woman aged 51, past the menopause, treated in Ankara, Turkey. She was referred because of a mass by her right ovary that was thought might be cancer. The paper does not describe her having symptoms. An internal ultrasound showed an enlarged right ovary with two mixed solid and fluid-filled lumps (2.5 cm and 2 cm). An MRI scan suggested the mass probably came from the right ovary. Her blood tumour markers were normal, including CA-125 at 5.8 U/mL.

What doctors did

Surgeons opened the tummy and found a 3 x 4 cm mixed solid and fluid-filled mass in the right ovary. The rest of the tummy and pelvis looked normal. The mass was removed and checked quickly under the microscope during the operation (a frozen section), which showed no cancer. They then removed the womb, both ovaries and both tubes. She went home on day 5. Under the microscope the tumour was well wrapped in a capsule, with sheets of cells and small tube-like spaces. There were no worrying cell changes, no dead tumour tissue, and very few dividing cells (0 to 1 per 10 high-power fields). Stains were positive for pancytokeratin, vimentin and calretinin, and negative for inhibin, Factor VIII and EMA. The final diagnosis was FATWO. No chemotherapy or radiotherapy was given. She was told about the risk of the tumour behaving like cancer and was followed up with check-ups, blood markers, ultrasound and MRI.

What happened

One year after surgery she had no symptoms and no sign of the tumour coming back. This is a single case, so it can't tell us what will happen to others.

Why it matters

FATWO in the ovary is less common than in the broad ligament. The authors say FATWO is very hard to diagnose before surgery and is diagnosed by ruling out other tumours that look similar, such as endometrioid carcinoma and Sertoli-Leydig cell tumour. From earlier papers they report that most returns happened in women who had only the tumour itself removed, and they describe complete removal with the womb, both ovaries and tubes as the most effective treatment reported so far, while noting that treatment is still not well defined. They note that the role of chemotherapy or radiotherapy is debated, that FATWO can come back or spread a long time after diagnosis (in earlier reports, the middle time to coming back was 48 months, range 13 to 96 months), and that tyrosine kinase inhibitor tablets could be considered for tumours that come back or spread, but data from many centres are needed to know whether they work. The authors advise long-term follow-up.

Checked line by line against the paper: 26 Oct 2026.

A short Indian pathology report describes a 36-year-old woman with six months of tummy pain and a lump, whose 10 cm tumour in the broad ligament was diagnosed as a benign FATWO from its appearance under the microscope.

The patient or patients

One woman aged 36 who had pain and a lump in the tummy for six months.

What doctors did

An open operation (exploratory laparotomy) found a lump lying purely in the broad ligament. The lump was firm and rounded, 10 x 8 x 5 cm, with a knobbly surface. Cut open, it was well enclosed, grey-white and even, with a few tiny cysts. Under the microscope, the tumour cells were arranged in cords and tubes within a fibrous background. The cells were uniform. Special stains showed PAS positivity and some reticulin positivity in the background tissue. The diagnosis of benign FATWO was made from how the tumour looked to the naked eye and under the microscope.

What happened

The report does not describe any follow-up. The authors say long-term follow-up is needed because FATWO can come back. This is a single case, so it can't tell us what will happen to others.

Why it matters

It adds a typical example of a benign FATWO in the broad ligament. The authors note that, although most FATWOs follow a benign course, about 10% come back or spread and are thought to resist chemotherapy and radiotherapy, quoting earlier work. They say surgery removing the womb and both tubes and ovaries appears to be the most successful first treatment.

Checked line by line against the paper: 26 Oct 2026.

Doctors in Indianapolis, USA, describe the ultrasound appearance of a FATWO in a woman in her mid-40s in a short report, but the abstract gives almost no details.

Written from the abstract only (full text could not be opened).

The patient or patients

One woman in her mid-40s who had had two pregnancies and two births.

What doctors did

The abstract says the report focuses on how the tumour looked on ultrasound, but it does not describe the scan findings, the operation or the lab results.

What happened

Not reported in the abstract. This is a single case, so it can't tell us what will happen to others.

Why it matters

The authors say little has been published about what FATWO looks like on ultrasound, and that it often causes symptoms that come on slowly.

Checked line by line against the paper: 26 Oct 2026.

A team reports a woman with FATWO who developed a serious clotting disorder (DIC) during her operation, which surgeons managed with pressure, a clotting agent and blood products.

Written from the abstract only (full text could not be opened).

The patient or patients

One woman with FATWO. The abstract does not give her age or other details.

What doctors did

During surgery she developed disseminated intravascular coagulation (DIC), a serious problem in which the blood's clotting system goes wrong and can cause heavy bleeding. The surgical team controlled it with pressure, a microfibrillar collagen haemostat (a material that helps blood clot) and blood products.

What happened

The bleeding problem during the operation was brought under control. The abstract states that the disease progressed after surgery. This paper also reports survival figures, which we have left out of this summary. This is a single case, so it can't tell us what will happen to others.

Why it matters

The authors note that FATWOs are usually considered of low malignant potential but are sometimes aggressive and can spread, that stain tests do not always settle the diagnosis, and that there is no standard treatment. They say that, although FATWO and DIC rarely occur together, surgeons operating on these tumours should be prepared for both.

Checked line by line against the paper: 26 Oct 2026.

Doctors in China describe a 45-year-old woman who had keyhole surgery for a lump in the tissue next to her right fallopian tube, which turned out to be a FATWO.

Written from the abstract only (full paper not free).

The patient or patients

One woman aged 45, reported by doctors at the Second Hospital of Jilin University, China. The abstract does not describe her symptoms.

What doctors did

She had a laparoscopy for a mass in the right mesosalpinx. The tissue was examined under the microscope and with stains.

What happened

The pathology showed a FATWO. The authors say stains (immunohistochemistry) play the biggest part in diagnosing FATWO. The abstract does not report any further treatment or follow-up. This is a single case, so it can't tell us what will happen to others.

Why it matters

The authors say FATWO's features are often overlooked, and they wrote the report to draw attention to it so that treatment, surgical options and outlook can be better judged.

Checked line by line against the paper: 26 Oct 2026.

A Turkish team describes a 55-year-old woman with a 5 cm FATWO in the right broad ligament whose tumour cells did not stain for Ki-67, a marker of dividing cells, which the authors take as a sign of a tumour with low malignant potential.

The patient or patients

One woman aged 55, treated in Ankara, Turkey. She came to clinic with heavy periods and pelvic pain. On examination she was tender low on the right side. An ultrasound scan showed a 4 cm fibroid in the wall of the womb and a 5 cm solid mass beside the right ovary.

What doctors did

Surgeons opened the tummy (laparotomy). The mass was in the right broad ligament and the other pelvic organs looked normal. They removed the womb, both ovaries and both tubes. The tumour came away easily with the womb. Under the microscope the pathologist first thought it was a Sertoli-Leydig cell tumour, but after stains the diagnosis was FATWO. The tumour was 3 x 4 x 5 cm, surrounded by a capsule, completely solid and had areas of calcium. Both ovaries were free of tumour. There were few dividing cells and no marked variation in cell shape. The tumour stained positive for vimentin and keratin, and negative for EMA, inhibin, oestrogen receptor, progesterone receptor and Ki-67. The paper reports no gene tests.

What happened

She recovered without problems and went home on the fifth day after surgery. She was told to see her doctor at least twice a year. The authors say no further treatment had been needed up to the time of writing. The paper does not say how long she had been followed up. This is a single case, so it can't tell us what will happen to others.

Why it matters

The authors say this is the second known FATWO to show no Ki-67 staining. They suggest Ki-67 may help doctors judge how a FATWO is likely to behave, alongside other warning features they list (dead tumour tissue, growth through the capsule, many dividing cells, very varied cells, and CD117 staining). They also say these warning signs can be absent in tumours that still come back. They conclude that firm treatment advice cannot be made without larger studies across many centres.

Checked line by line against the paper: 26 Oct 2026.

A Japanese team describes a 36-year-old woman with a 6 cm FATWO in the right broad ligament and sets out in detail how it looked on MRI, hoping such features might one day help doctors suspect FATWO before an operation.

The patient or patients

One woman aged 36, treated in Tokyo, Japan. She had been pregnant twice but had no children. She was sent to hospital because an ovarian tumour was suspected. On examination there was a hen's-egg-sized lump on the right side. Blood tests were normal, including tumour markers (CA-125 was 12 U/ml). Ultrasound showed a 6 cm solid mass with small cysts behind a normal womb.

What doctors did

Before surgery she had MRI and CT scans. On MRI the mass was well defined and oval, about 6 cm across. It was slightly brighter than muscle on one type of image (T2), the same as muscle on another (T1), lit up evenly with contrast dye, and showed 'restricted diffusion', which suggests tightly packed cells. The centre looked like it might have broken down. CT showed curved and dotted specks of calcium. A normal right ovary was seen next to the mass. At operation the tumour sat in the right broad ligament and was partly joined to the right fallopian tube. There was no sign of spread, and a small amount of brownish fluid in the pelvis. Surgeons removed the right tube and ovary together with the tumour. A quick test during the operation (frozen section) suggested a Wolffian tumour. The removed tumour measured about 5 x 6 x 6.5 cm, was solid, white-yellow, with small cysts. Under the microscope there were 1 to 2 dividing cells per 10 high-power fields, no abnormal dividing cells and no growth into blood vessels. The tumour surface was intact and it was called stage 1a. Stains were positive for CAM 5.2, vimentin, calretinin and CD10, and negative for EMA, ER, PgR and D2-40.

What happened

The paper does not report any follow-up after surgery. This is a single case, so it can't tell us what will happen to others.

Why it matters

Few papers describe how FATWO looks on scans. The authors say their MRI findings matched one earlier report and add findings from diffusion imaging. They say these MRI features 'might be one of the common features' of FATWO, but also that they look like other solid ovarian tumours, such as granulosa cell tumour, Sertoli-Leydig cell tumour, thecofibroma and dysgerminoma. So stains on the removed tumour were still needed to make the diagnosis. They hope newer MRI methods may help in future.

Checked line by line against the paper: 26 Oct 2026.

A US team reports one woman with a malignant FATWO that had spread widely, reviews earlier reports, and advises long-term follow-up because FATWO can behave aggressively, sometimes years later.

Written from the abstract only (full paper not free).

The patient or patients

One woman with disseminated (widely spread) malignant FATWO. She was reported by a pathology team in New Jersey, USA. The abstract gives no age, symptoms or other details.

What doctors did

The abstract does not describe her treatment. The authors also reviewed the published literature.

What happened

The abstract says only that the case was a rare one of disseminated malignant FATWO. No treatment or outcome is given. This is a single case, so it can't tell us what will happen to others.

Why it matters

The authors say FATWO grows where Wolffian remnants are found, such as the broad ligament. It is thought of as benign, but this is not always so: scattered reports describe more aggressive behaviour, sometimes years later. They conclude FATWO can behave in a malignant way, that knowing about it helps doctors recognise it, and the authors advise long-term follow-up.

Checked line by line against the paper: 26 Oct 2026.

American doctors describe a 38-year-old woman whose FATWO came back on the surface of her left ovary three years after it was removed; the tumour stained strongly for c-kit, no c-kit gene changes were found, and she was started on the targeted tablet imatinib.

The patient or patients

One woman aged 38, treated at Roswell Park Cancer Institute in Buffalo, New York, USA. In 2007 she had a 12 x 11 x 10 cm lump growing from the right broad ligament (the sheet of tissue beside the womb), with no other disease seen in the pelvis or tummy. Some time after this she was diagnosed with invasive breast cancer. In 2010, while taking tamoxifen, she had abnormal bleeding from the womb.

What doctors did

First operation (2007): the lump was removed on its own. Two outside expert pathologists agreed it was likely a FATWO. Second operation (2010, because of abnormal bleeding): removal of the womb, both tubes and both ovaries. The left ovary had several small firm lumps on it, and the quick test during surgery showed a poorly differentiated tumour, so full staging was done: removal of the omentum and the lymph nodes in the pelvis and along the main blood vessels. Under the microscope the tumour sat on the surface of the left ovary without growing into it, with a sieve-like pattern and only slightly abnormal cells. The womb, omentum and lymph nodes were clear. Stains: AE1/3, cytokeratin (CK)7, WT1, calretinin and α-inhibin positive; epithelial membrane antigen (EMA), CK20 and synaptophysin negative; C-kit (CD117) strongly positive. Comparing it with the 2007 tumour showed the same look and stain pattern, so it was judged to be the FATWO coming back. Gene testing: the lab tested parts (exons 9, 11, 13 and 17) of the C-kit gene and parts (exons 12 and 18) of the PDGFR gene, and found no changes. She was then started on imatinib mesylate (Gleevec) 400 mg by mouth daily for 6 months, with CT scans every 6 months.

What happened

The FATWO came back 3 years after the first operation, as several small lumps on the surface of the left ovary, the largest 1.9 x 1.7 x 0.6 cm. The returned tumour had many more dividing cells than the first (15 per 10 high-power fields, compared with 1). She had no problems after surgery and went home 3 days later. The paper does not report how she responded to imatinib, as she had only just started it. This is a single case, so it can't tell us what will happen to others.

Why it matters

This is an early report of testing a FATWO for c-kit as a possible target for treatment; the paper says c-kit had been found in only 2 earlier cases. The authors chose imatinib because the tumour came back within 3 years, was strongly c-kit positive, there were no proven treatments, and imatinib has few serious side effects. They point out that their gene test only checked some parts of the genes, so a change could have been missed. They say chemotherapy and radiotherapy have not been shown to work in FATWO that has come back, that imatinib 'could be considered' for c-kit-positive FATWO that has come back, and that a multi-centre effort is needed to find out whether it works. No STK11 testing was done; later papers treat STK11-changed tumours as a separate type.

Checked line by line against the paper: 26 Oct 2026.

A US radiologist reports the first known case of FATWO spreading to the appendix, seen on an FDG PET/CT scan, and warns that this kind of uptake in the appendix can be mistaken for normal bowel activity.

Written from the abstract only (full paper not free).

The patient or patients

One patient with FATWO that had spread to the appendix. The abstract gives no age, symptoms or treatment history.

What doctors did

An FDG PET/CT scan was done, which showed the spread to the appendix.

What happened

The scan showed uptake of FDG in the appendix, caused by FATWO that had spread there. The author says this had not been reported before, and that there was little published on PET/CT in FATWO. This is a single case, so it can't tell us what will happen to others.

Why it matters

The author advises that people reading PET/CT scans take care to look for uptake in the appendix, because it is easily mistaken for normal bowel activity.

Checked line by line against the paper: 26 Oct 2026.

An Italian team describes a 48-year-old woman whose 6 cm FATWO was removed, and her whole pelvis and abdomen checked for spread, in a single keyhole (laparoscopic) operation, with no further treatment given and no sign of it coming back a year later.

The patient or patients

One woman aged 48, treated in Bologna, Italy. She had never given birth and had no symptoms; a pelvic mass had recently been found. Ultrasound showed a 5 cm solid mass beside the right ovary with an irregular outline and a good blood supply, which looked like it could be cancer. Both ovaries were normal. MRI confirmed the mass. A chest X-ray was normal. CA-125 and other tumour markers were negative.

What doctors did

After a full discussion with her, surgeons did a keyhole operation. The mass was attached by a stalk to the end of the right tube. There were some small clear blisters on the lining of the pelvis but no other visible disease and no fluid. Fluid washed from the tummy contained tumour cells. The mass was removed whole in a bag to avoid spilling it. A quick test during surgery (frozen section) suggested a poorly differentiated adenocarcinoma. So, in the same operation, the team removed both ovaries and tubes, the womb, the omentum and the lining of the pelvic walls, and 56 lymph glands from the pelvis and along the main blood vessels. The operation took 4 hours 15 minutes with no complications, and she went home on day 6. The final examination showed a well-encapsulated 6 x 5 x 2 cm solid tumour in the right broad ligament. Stains were strongly positive for vimentin, calretinin, inhibin and pan-cytokeratin (MNF 116), and negative for CK7 and chromogranin. All other removed tissue and all 56 lymph glands were clear. A national cancer centre in Milan confirmed the diagnosis of FATWO.

What happened

A team of cancer specialists decided no further treatment was needed, because the staging was complete and the tumour did not show aggressive features. She was followed up with check-ups and scans. One year after surgery she had no symptoms, normal tests and no sign of the tumour coming back. This is a single case, so it can't tell us what will happen to others.

Why it matters

The authors say this was the first FATWO managed entirely by keyhole surgery in a single operation. In many earlier cases women needed a second operation once the final diagnosis was known. The authors stress that the frozen section allowed them to do complete staging in one go, and they advise referring women with a suspicious mass beside the ovary to a specialist centre with dedicated scan, surgery and pathology teams.

Checked line by line against the paper: 26 Oct 2026.

A Korean team describes a 52-year-old woman with a 12 cm FATWO that had a very high number of dividing cells and had grown into the outer layer of the fallopian tube; after full surgery and three cycles of paclitaxel and carboplatin there was no sign of it coming back at the last check.

The patient or patients

One woman aged 52, treated in Seoul, Korea. She had had four pregnancies and three children. She was referred in May 2008 with a pelvic mass and a raised CA-125 (87.8 U/mL). Ultrasound showed an 11 x 9 x 8 cm part-solid, part-fluid mass by the womb. A CT scan suggested a breaking-down fibroid on the outside of the womb.

What doctors did

Surgeons opened the tummy, expecting a fibroid. They found a large solid yellow mass, 12 x 9 x 7.5 cm, that seemed to be growing into the nearby fallopian tube. A quick test during surgery (frozen section) showed a FATWO with many dividing cells (up to 36 per 10 high-power fields). They then removed the womb, both ovaries and tubes and the omentum, and lymph glands from the pelvis and along the aorta. Under the microscope the tumour was well encapsulated with tubes, cords, sieve-like and solid areas. There was some bleeding inside it but no dead tissue. It had grown into the outer layer of the tube. All 35 lymph glands and the omentum were clear. Stains were positive for pan-cytokeratin, CD10, inhibin-alpha, oestrogen receptor and C-kit, and negative for cytokeratin 7 and cytokeratin 20. Ki-67 showed a raised rate of dividing cells (10 to 40%). Because of the very high cell-division rate and the growth into the tube, she then had three cycles of chemotherapy with paclitaxel (175 mg/m2) and carboplatin (AUC 5).

What happened

In the 10 months after chemotherapy (the abstract says 12 months of follow-up), she showed no sign of the tumour coming back or spreading. Follow-up was continuing. This is a single case, so it can't tell us what will happen to others.

Why it matters

The authors say this was the first malignant FATWO reported in Korea and had the highest count of dividing cells reported up to then. They note that malignant FATWO is very rare and its behaviour is hard to predict. They stress the value of a frozen section when an unusual mass is found where Wolffian remnants lie, because it changes the operation. They say it is unclear whether chemotherapy or radiotherapy after surgery helps; this woman was given chemotherapy because of the features of her tumour. They also mention earlier reports of imatinib (which they spell 'Gleevac') for C-kit-positive FATWO and of hormone treatment.

Checked line by line against the paper: 26 Oct 2026.

A review of 63 published FATWO cases with follow-up found that the tumour came back or remained in about 1 in 9 women, so the author concludes FATWO cannot be regarded as a benign (harmless) tumour.

Written from the abstract only (full paper not free).

The patient or patients

63 women with FATWO, described in 31 published papers, who had follow-up information. Ages and countries are not given in the abstract.

What doctors did

This is a review of published cases, not a treatment study. The author searched two medical databases (Medline and Embase) and checked whether features of the tumour were linked to how the women did.

What happened

Seven of the 63 women (11.1%, about 1 in 9) had the tumour come back or had tumour left behind. A higher stage (how far the tumour had spread when found) and how the cells looked under the microscope (differentiation) were linked to outcome. Unusual-looking cells (atypia) came close to being linked. Age, tumour size, where the tumour was, how fast the cells were dividing and areas of dead tissue (necrosis) were not linked to outcome. This paper also reports survival figures, which we have left out of this summary.

Why it matters

Even though many FATWOs behave gently, this review showed that some do not, so FATWO should not be assumed to be harmless. It also warns that FATWO can be confused with some well-differentiated gynaecological cancers, so careful testing with stains is important to get the diagnosis right.

Checked line by line against the paper: 26 Oct 2026.

Doctors in Croatia describe a 60-year-old woman whose FATWO came back at the top of the vagina 6 years after her first operation, was removed again without chemotherapy, and showed no sign of disease 2 years later.

Written from the abstract only (full paper not free).

The patient or patients

One woman aged 60, reported by doctors in Zagreb, Croatia. Six years earlier she had been diagnosed with FATWO and had a hysterectomy, removal of both tubes and ovaries, and removal of the omentum. She had no chemotherapy after that first operation.

What doctors did

In 2006 a CT scan of the tummy and pelvis confirmed a solid tumour on the vaginal cuff. Surgeons took pelvic washings, freed scar tissue (adhesions) and cut out the tumour. She had no chemotherapy after this second operation either.

What happened

The tumour on the vaginal cuff was a malignant epithelial tumour of Wolffian origin, looking similar to her first tumour. It stained positive for vimentin and partly, weakly for cytokeratin 19. Two years after the second operation she had no symptoms, and her examination, blood tests, CT and chest X-ray were normal. This is a single case, so it can't tell us what will happen to others.

Why it matters

It shows a FATWO coming back many years after the first operation, and being managed with surgery alone. The authors conclude that surgery to remove as much tumour as possible, with hysterectomy and removal of both tubes and ovaries, appears to be the most successful first treatment for FATWO.

Checked line by line against the paper: 26 Oct 2026.

A US pathology team describes an 87-year-old woman whose ovary held a Wolffian tumour that largely looked like a fibroma (a usually harmless growth) under the microscope, showing how important it is to sample the tissue thoroughly.

Written from the abstract only (full paper not free).

The patient or patients

One woman aged 87, reported by a pathology team based in New Jersey, USA. She was having an operation for endometrioid cancer of the womb.

What doctors did

She had a total abdominal hysterectomy and removal of both tubes and ovaries for her womb cancer. A 4.5 cm part-solid, part-cystic mass was found on the right ovary. A frozen section was done during surgery, then the ovary mass was sampled extensively. A stain for CD117 (c-kit) was done because earlier reports had suggested imatinib (Gleevec) might help Wolffian tumours.

What happened

The frozen section showed bland spindle cells that looked like a cellular fibroma. Extensive sampling found an area with the classic sieve-like pattern of a Wolffian adnexal tumour, merging into the fibroma-like areas. The womb showed a well-differentiated, superficially invasive endometrioid cancer arising from atypical complex hyperplasia. The CD117 stain was negative. She had no further treatment, and the authors report no sign of disease 7 months after surgery. This paper also reports survival figures, which we have left out of this summary. This is a single case, so it can't tell us what will happen to others.

Why it matters

It shows that Wolffian tumours of the ovary can look very different in different areas, and that a small sample could miss the diagnosis. The authors say thorough sampling is crucial.

Checked line by line against the paper: 26 Oct 2026.

A Nottingham team describes an 81-year-old woman with a 14 cm malignant FATWO, which came back 7 months after surgery.

Written from the abstract only (full paper not free).

The patient or patients

One woman aged 81, reported by a hospital team in Nottingham, UK. She had 6 months of bleeding after the menopause.

What doctors did

An internal (transvaginal) ultrasound showed a mainly solid mass about 14 cm across, behind the womb, with a lot of blood vessels. CA-125 was moderately raised. She had a total abdominal hysterectomy, removal of both tubes and ovaries, and removal of the lower omentum. The tumour was examined with stains and electron microscopy.

What happened

Stains and electron microscopy supported a diagnosis of FATWO. There was marked, widespread variation in cell nuclei and more dividing cells, which the authors took as signs of a malignant tumour. Seven months after surgery an MRI scan showed a 7 cm mass in the right adnexa, in keeping with the tumour coming back. She declined further treatment. This is a single case, so it can't tell us what will happen to others.

Why it matters

The authors say the features of malignant FATWO are not well defined because these tumours are so rare. This case adds a description of microscope features (marked nuclear variation and more cell division) linked with malignant behaviour.

Checked line by line against the paper: 26 Oct 2026.

Doctors in Meerut, India, describe a 56-year-old woman with a slowly growing lump in her lower tummy, which was a FATWO in the right broad ligament.

Written from the abstract only (full paper not free).

The patient or patients

One woman aged 56, with a lump in her lower tummy that had been gradually getting bigger for a year.

What doctors did

She had an open operation (laparotomy). A part-solid, part-cystic mass was removed from the right broad ligament, along with a pan-hysterectomy.

What happened

Examination under the microscope showed a tumour of Wolffian origin. The abstract does not report follow-up. This is a single case, so it can't tell us what will happen to others.

Why it matters

The authors note this tumour has rarely been reported in Indian medical journals.

Checked line by line against the paper: 26 Oct 2026.

Doctors in Naples, Italy, describe a FATWO in a 22-year-old woman, described by the authors as the youngest patient, which was fully removed and showed very little cell growth.

Written from the abstract only (full paper not free).

The patient or patients

One woman aged 22, who had never had sex (the paper notes this). The authors describe her as the youngest patient affected by FATWO, and mention October 2002.

What doctors did

At an open operation (laparotomy) the left adnexa was distorted by a well-encapsulated mass. It was completely removed and sent to the lab, with a sample of tummy fluid and of the omentum. The tumour was examined with stains and with flow cytometry.

What happened

The tumour was mainly made of small tubes, with some net-like areas and no mucus inside the tubes. The stain results were similar to other reports, except that inhibin was not found. Flow cytometry showed few cells with abnormal amounts of DNA and a very low share of growing cells (less than 1%). The abstract does not report follow-up. This is a single case, so it can't tell us what will happen to others.

Why it matters

It shows FATWO can occur in young women. The authors note about 40 cases had been reported, few had come back, and FATWO usually shows no signs of making hormones.

Checked line by line against the paper: 26 Oct 2026.

Doctors in Japan describe a 50-year-old woman with a FATWO beside the right fallopian tube whose tumour weakly showed the KIT protein, but gene testing found no change in the c-kit gene.

Written from the abstract only (full paper not free).

The patient or patients

One woman aged 50, from Japan, with a FATWO beside the right fallopian tube (paratubal).

What doctors did

The tumour was examined under the microscope, with stains and with electron microscopy. Its DNA was tested for changes in exons 9 and 11 of the c-kit gene. The cells were also described under the microscope in a cytology (cell) sample.

What happened

The tumour looked and stained like a typical FATWO. The KIT protein was weakly present throughout the tumour, but the DNA test found no change in exon 9 or 11 of the c-kit gene. The abstract does not give treatment or follow-up. This is a single case, so it can't tell us what will happen to others.

Why it matters

The authors say about 10% of FATWOs come back or spread and are thought not to respond well to chemotherapy or radiotherapy. In 2004 imatinib, a targeted drug, was reported to help one KIT-positive FATWO. This paper is described as the first to check the c-kit gene in FATWO. The authors believe collecting gene data on FATWO is important for treatment, even though this case had no gene change. It also gives the first description of FATWO cells in a cytology sample.

Checked line by line against the paper: 26 Oct 2026.

Doctors report a woman with a type of lymphoma whose scans showed a pelvic mass that did not shrink with lymphoma chemotherapy, and which turned out at operation to be a FATWO.

Written from the abstract only (full paper not free).

The patient or patients

One woman aged 55 who had been diagnosed with non-Hodgkin lymphoma (extranodal diffuse large B-cell lymphoma).

What doctors did

Tests to stage her lymphoma found a mass in the pelvis. She had chemotherapy for the lymphoma, but the pelvic mass did not shrink. Surgeons then carried out an open operation to look inside the tummy (explorative laparotomy), and the mass was found to be a FATWO.

What happened

The abstract says only that the mass was a FATWO, found alongside the lymphoma. It gives no detail of further treatment or follow-up. This is a single case, so it can't tell us what will happen to others.

Why it matters

The authors believe this is the first case in the English-language medical literature of a FATWO found at the same time as an extranodal diffuse large B-cell lymphoma.

Checked line by line against the paper: 26 Oct 2026.

Doctors report a young woman whose malignant FATWO came back three years after surgery, one month after she gave birth, and suggest the tumour might be affected by hormones.

Written from the abstract only (full paper not free).

The patient or patients

One woman aged 27 with a mass on the left side next to the womb (left adnexa).

What doctors did

She had an open operation (laparotomy) to remove the left adnexal mass. Lab examination showed it was a FATWO. Stains on the tumour (immunohistochemistry) showed progesterone receptors.

What happened

The tumour came back three years after the first operation, one month after she gave birth vaginally. The abstract does not say how the recurrence was treated. This is a single case, so it can't tell us what will happen to others.

Why it matters

Most FATWOs behave in a benign way. The authors found progesterone receptors on the tumour and suggest that FATWO may in some cases depend on hormones, which might explain why this one came back after pregnancy. This is a suggestion from one case, not a proven link.

Checked line by line against the paper: 26 Oct 2026.

A Canadian team (Princess Margaret Hospital, Toronto) describes a 15-year-old girl whose FATWO came back within two years; after chemotherapy and surgery, her tumour was found to carry the c-kit protein and she was given the targeted drug imatinib (Gleevec), with signs that it may have helped.

Written from the abstract only (full paper not free).

The patient or patients

One girl aged 15, treated in Toronto, Canada, who had a painful pelvic mass.

What doctors did

She had an operation (laparotomy) to remove the tumour, and tests confirmed a FATWO. When it came back, she was given several chemotherapy combinations, including a platinum-based drug, and had surgery when the disease grew. The tumour was positive for c-kit (CD117), so she was prescribed imatinib (the abstract spells it 'Gleevac'), a targeted tablet. Two months later she developed severe, ongoing lower tummy pain and had an operation to remove the womb and tumour deposits at the back of the tummy. Imatinib was then restarted to try to stop the tumour coming back.

What happened

The tumour came back within 2 years of the first operation. In the tumour removed after imatinib, the pathologists saw areas of dead tumour tissue (necrosis), which the authors suggest may mean the drug had an effect. At the time of writing, 10 months after the last operation, she had no symptoms and no sign of the tumour, and was still taking imatinib. This is a single case, so it can't tell us what will happen to others.

Why it matters

The authors put forward imatinib as a possible new treatment for FATWO (the paper's title calls it "a possible new treatment"). The authors say her 'favorable response' supports the idea of targeted treatment for c-kit-positive FATWO. They also say that knowledge about the best treatment for this tumour is limited.

Checked line by line against the paper: 26 Oct 2026.

The authors describe two FATWOs of the broad ligament and find that the proteins holding the tumour cells together were intact and very few cells were dividing, which they think may explain why FATWO is usually slow-growing.

Written from the abstract only (full paper not free).

The patient or patients

Two women with FATWO in the broad ligament. Ages are not given in the abstract.

What doctors did

The tumours were examined under the microscope and with stains. The team also looked at normal leftover Wolffian (mesonephric) duct tissue to compare. They tested for cell-to-cell 'glue' proteins (E-cadherin, alpha-catenin and beta-catenin) and for Ki-67, a marker of dividing cells.

What happened

Both tumours were well-defined solid masses in the broad ligament, with a sieve-like mix of small cysts and tubes. The tumours stained for cytokeratin 7 and 20, high-molecular-weight cytokeratin and calretinin, a pattern close to the leftover mesonephric duct tissue. Results for CK 20, CD 10, EMA, S-100 protein and vimentin partly differed from earlier studies. E-cadherin and alpha- and beta-catenin were strongly present on the cell surfaces. Ki-67 showed 0% of cells dividing in one tumour and 3.2% in the other.

Why it matters

The authors say FATWO is usually slow-growing (indolent), though some cases come back or spread. They suggest that the intact cell 'glue' proteins and low rate of cell division could explain this usually slow-growing behaviour and low malignant potential. The tumours' stain pattern closely resembled that of leftover mesonephric (Wolffian) duct tissue.

Checked line by line against the paper: 26 Oct 2026.

Two Czech authors describe two FATWOs, one very large in the ovary of an older woman and one smaller on a stalk from the broad ligament, both of which behaved benignly on follow-up.

Written from the abstract only (full paper not free).

The patient or patients

Two women. One was 85 with an 18 cm tumour in the ovary. The other was 40 with a 5 cm mass on a stalk (pedunculated) growing from the broad ligament.

What doctors did

The tumours were examined under the microscope. The abstract does not describe the operations.

What happened

Both tumours showed a mix of three patterns: solid, sieve-like and tube-like, made of spindle-shaped or lining-type cells. The cells looked almost normal and there were practically no dividing cells. Follow-up confirmed benign behaviour in both women.

Why it matters

These cases add to the evidence that many FATWOs behave in a benign way. The authors also discuss which other tumours FATWO can be confused with and review the literature.

Checked line by line against the paper: 26 Oct 2026.

A Korean team (Keimyung University, Daegu) reports one woman with a broad ligament tumour showing the features of FATWO, and describes how it looked under the ordinary microscope, the electron microscope and with special stains.

Written from the abstract only (full text could not be opened).

The patient or patients

One woman. The abstract gives no age, symptoms or tumour size.

What doctors did

The abstract says the team examined the tumour with light microscopy, electron microscopy and immunohistochemical stains. It does not describe the operation or any other treatment.

What happened

The abstract does not report the outcome. This is a single case, so it can't tell us what will happen to others.

Why it matters

It adds one more case to the small number of published FATWOs. The authors note that FATWO is rare, can be hard to diagnose, and usually grows in the broad ligament.

Checked line by line against the paper: 26 Oct 2026.

The authors report two women with FATWO: one whose tumour came back widely three years after surgery and again four months after further surgery, and one with possible signs of return on a scan a year after surgery.

Written from the abstract only (full paper not free).

The patient or patients

Two women. The first was 38, a Latin American woman who had had six pregnancies and six births, and who came with lower tummy pain and a pelvic mass. Three years earlier she had had her womb, both tubes and ovaries removed, when a small nodule beside the tube was found by chance and turned out to be FATWO. The second was a 71-year-old Caucasian woman who had had an operation to remove as much of a FATWO as possible.

What doctors did

First woman: scans showed widespread tumour in the tummy and pelvis. This was confirmed at an open operation and as much tumour as possible was removed (debulking). When it came back again she was given systemic (whole-body) therapy. Second woman: she had a routine check one year after her operation, including a CT scan.

What happened

First woman: the tumour came back widely three years after the first operation, and came back a second time four months after debulking. At the time of writing she was having systemic therapy. Second woman: the CT scan one year after surgery showed possible signs of the tumour coming back.

Why it matters

The authors say most FATWOs behave in a benign way but there is a potential risk of them coming back. They suggest that removing the womb, both tubes and ovaries at diagnosis may be the best treatment, and that the role of extra radiotherapy or chemotherapy after surgery remains uncertain.

Checked line by line against the paper: 26 Oct 2026.

Pathologists compared stains on FATWOs with normal leftover Wolffian (mesonephric) tissue and normal Müllerian (paramesonephric) tissue, finding a pattern that supports a Wolffian origin and a stain (GST mu) that may help with diagnosis.

Written from the abstract only (full paper not free).

The patient or patients

Tumour samples from women with FATWO, compared with normal mesonephric remnants and paramesonephric tissue. The number of cases is not given in the abstract.

What doctors did

Standard stains were done on tissue samples preserved in formalin.

What happened

Tumours and both kinds of normal tissue were generally positive for vimentin, CAM 5.2 and cytokeratins 7 and 19, and negative for CK20 and 34 beta E12. EMA was positive in both kinds of normal tissue but negative in the tumours. Glutathione S-transferase mu (GST mu) was generally positive in tumours and mesonephric tissue but negative in paramesonephric tissue.

Why it matters

The authors say stains play little part in diagnosing FATWO, but the tumours are usually cytokeratin and vimentin positive and EMA negative. They suggest GST mu, as a marker of mesonephric tissue, is a useful extra test. They conclude their findings support, but do not prove, that FATWO comes from Wolffian (mesonephric) tissue.

Checked line by line against the paper: 26 Oct 2026.

A US team reports a woman whose FATWO grew in the broad ligament and, five years later, appeared in the liver.

Written from the abstract only (full text could not be opened).

The patient or patients

One woman aged 60.

What doctors did

The authors studied the original tumour and the tumour in the liver: how they looked under the microscope, their stains, their fine structure under an electron microscope, and the amount of DNA in the cells (DNA ploidy). They also discuss which other tumours FATWO can be confused with and review the English-language medical literature.

What happened

The FATWO grew within the layers of the broad ligament. Five years later it presented with spread (metastasis) to the liver. The abstract does not give the results of the tests or say how she was treated. This is a single case, so it can't tell us what will happen to others.

Why it matters

The authors describe FATWO as a rare tumour that can be hard to diagnose. This case shows that a FATWO can spread to the liver years after it was first found.

Checked line by line against the paper: 26 Oct 2026.

Radiologists report the MRI appearance of one FATWO, which they say had not been described before.

Written from the abstract only (full paper not free).

The patient or patients

One woman with a FATWO. The abstract gives no details about her.

What doctors did

An MRI scan was done and the authors describe what the tumour looked like.

What happened

The abstract does not describe the MRI findings themselves. This is a single case, so it can't tell us what will happen to others.

Why it matters

The authors say this was the first report of what FATWO looks like on MRI. They describe FATWO as a rare tumour that arises from leftovers of the Wolffian duct.

Checked line by line against the paper: 26 Oct 2026.

Pathologists in Jamaica report one FATWO of the broad ligament and discuss where it comes from, what it can be mistaken for, and how it behaves.

Written from the abstract only (full paper not free).

The patient or patients

One woman with a FATWO of the broad ligament. The abstract gives no other details.

What doctors did

Not described in the abstract.

What happened

Not described in the abstract. This is a single case, so it can't tell us what will happen to others.

Why it matters

It adds one more case of this rare tumour, from the Caribbean.

Checked line by line against the paper: 26 Oct 2026.

Doctors report a FATWO in a 23-year-old woman, the youngest reported at the time, who had no sign of it coming back 11 years after surgery and went on to have three children.

Written from the abstract only (full paper not free).

The patient or patients

One woman aged 23.

What doctors did

She was treated with surgery. The abstract does not say what operation was done.

What happened

Eleven years after surgery there had been no sign of the tumour coming back or spreading, and she had given birth to three children. This is a single case, so it can't tell us what will happen to others.

Why it matters

The authors say she was the youngest woman described with this tumour at the time. Her case shows that, in at least one young woman, surgery was followed by a long time without return and later pregnancies.

Checked line by line against the paper: 26 Oct 2026.

The authors compared stains on 25 Wolffian adnexal tumours with normal Wolffian leftovers and found the tumours most closely matched the rete ovarii, supporting a Wolffian origin.

Written from the abstract only (full paper not free).

The patient or patients

25 tumours. Each was on one side only: broad ligament (10), mesosalpinx (9), ovarian hilus (5) and pelvis, site not specified (1). They were compared with 10 mesonephric remnants from the cervix and vagina and 12 rete ovarii samples.

What doctors did

A panel of stains was done on all the samples.

What happened

The tumours had solid (spindle cell), tubular, net-like (retiform) and many-cyst patterns. Stain results: pan-cytokeratin (AE1/3, CK1) 100%, CAM 5.2 100%, cytokeratin 7 (CK7) 88% (focal), keratin 903 17%, epithelial membrane antigen (EMA) 12%, oestrogen receptor 28%, progesterone receptor 24%, androgen receptor 78%, inhibin 68%, calretinin 91%, vimentin 100%. None stained for monoclonal carcinoembryonic antigen or cytokeratin 20. This pattern was nearly identical to the rete ovarii. It differed somewhat from mesonephric remnants, which were diffusely CK7 positive, EMA positive and inhibin negative.

Why it matters

The authors say this supports the idea that these tumours come from Wolffian leftovers, particularly the rete ovarii. Because many tumours were positive for inhibin and calretinin, they warn that these stains alone cannot reliably tell FATWO apart from sex cord-stromal tumours and adenomatoid tumours.

Checked line by line against the paper: 26 Oct 2026.