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Last updated: 3/14/2025
Years published: 2025
NORD gratefully acknowledges Gioconda Alyea, MD (FMG), MS, National Organization for Rare Disorders, for assistance in the preparation of this report.
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Summary
Female adnexal tumor of probable Wolffian origin (FATWO) is a very rare type of tumor that forms in the female reproductive system. It is considered to have low malignant potential, meaning it usually grows slowly and doesn’t often spread (metastasize) to other parts of the body.1
The tumor is thought to develop from remnants of the Wolffian duct, a structure present during fetal development. This duct usually disappears in females as they grow but rarely, leftover tissue can form into a tumor like FATWO.1
Introduction
The tumor was first described in 1973 and named based on its location in the broad ligament, an area rich in Wolffian remnants.1 The Wolffian duct system passes through several areas of the female reproductive system including the broad ligament, fallopian tubes, ovaries and the lining of the abdominal cavity (peritoneum). This explains why FATWO is usually found in the broad ligament but can also appear in other areas like the ovaries, fallopian tubes, or the space near the vagina.1,2
Treatment includes surgery to remove the tumor.
Many females with FATWO have no symptoms. When symptoms do occur, they are often vague and may include:1
The tumor is often discovered accidentally during physical exams or surgeries for other conditions. FATWO has been diagnosed in females between the ages of 15 and 83, with the average age being 50 years.1
The most common locations are: 1
Most people with FATWO have normal levels of a blood marker called CA-125 (cancer antigen 125), a protein found on the surface of certain cancer cells which is sometimes used to detect other gynecologic tumors. Currently, there are no specific blood tests or biomarkers to identify FATWO.1,2,3
FATWO is extremely rare. Worldwide, there are only about 100 cases reported in the medical literature.3
Diagnosing FATWO can be difficult. Although it is usually a benign (non-cancerous) tumor, an accurate diagnosis is important because it may determine the type of surgery a person needs. Currently, there are no specific blood tests (biomarkers) that can always detect FATWO, making it hard to suspect before surgery.2
Medical imaging like MRI, CT scans and ultrasounds help doctors evaluate FATWO, but it can look similar to other tumors.
If symptoms are present, doctors may begin with a pelvic ultrasound which can show a semisolid, well-vascularized mass. An ultrasound is a medical imaging test that uses sound waves to create pictures of the organs.
CT scans (computed tomography) provide more detailed images and help determine the tumor’s location, size and whether it has spread. CT scans show FATWO as a mix of solid and cystic areas with uneven enhancement. CT is a medical imaging technique that uses X-rays to create detailed, cross-sectional images of the body’s internal structures.
Magnetic resonance imaging (MRI) is a non-invasive medical imaging technique that uses strong magnetic fields and radio waves to create detailed images of the body’s internal structures. Images often show a slightly bright mass with areas that appear cystic, making it hard to distinguish from other growths like fibroids or ovarian tumors.
After surgery, the tumor is examined under a microscope. It may appear as solid-to-cystic masses with a gray-yellow color. Under the microscope, these tumors can have different patterns (sieve-like, tubular, or sheet-like) but generally have uniform, low-grade cells. Although some features overlap with Sertoli-Leydig tumors, the presence of Leydig cells and endocrine symptoms (hormone-related changes) can help differentiate them.1,2
The tumor cells are often small and uniform with low rates of cell division, meaning they are not very aggressive. Specialized staining techniques can also help confirm the diagnosis.1
Treatment
The primary treatment for FATWO is surgical removal of the tumor. In most people, this involves removal of the uterus (total hysterectomy) along with the removal of both ovaries and fallopian tubes.3,4
Most FATWOs are benign, meaning they don’t spread or come back after treatment. However, in about 11% of cases the tumor may spread (metastasize) to areas like the liver or lungs.3,4 In these cases, the recurrences can happen years after the initial diagnosis even if the tumor didn’t initially appear aggressive.3
Features like dead tissue (necrosis), spreading beyond the tumor’s outer covering (capsular invasion), or high levels of certain proteins like Ki-67 or CD117 may indicate a more aggressive tumor.3
For rarer cases where the tumor spreads or comes back, treatment options may include:1,3,4,5,6,7,8,9
Most tumor recurrences occur in patients initially treated with conservative procedures such as cystectomy or simple tumor resection. When FATWO does recur or spread, this happens on average after about 3 years, but this can range from 4 months to 8 years after the initial diagnosis.9 While there is no standardized treatment for recurrent or metastatic FATWO, doctors often combine chemotherapy with other therapies to improve survival.3
However, due to its rarity, the optimal management of recurrent FATWO has not been established. Additional chemotherapy, radiotherapy, hormone therapy and target therapy have been used to treat patients with recurrent and metastatic FATWO but these treatments are controversial and still require further research.7
The prognosis for FATWO is generally good for most patients, especially when the tumor is completely removed. However, because the condition is so rare, long-term outcomes are not known. Regular follow-up is essential, as recurrences can happen even after successful initial treatment.3
Information on current clinical trials is posted on the Internet at https://clinicaltrials.gov/. All studies receiving U.S. Government funding, and some supported by private industry, are posted on this government web site.
For information about clinical trials being conducted at the NIH Clinical Center in Bethesda, MD, contact the NIH Patient Recruitment Office:
Toll-free: (800) 411-1222
TTY: (866) 411-1010
Email: [email protected]
Some current clinical trials also are posted on the following page on the NORD website:
https://rarediseases.org/living-with-a-rare-disease/find-clinical-trials/
For information about clinical trials sponsored by private sources, contact:
https://www.centerwatch.com/
For information about clinical trials conducted in Europe, contact:
https://www.clinicaltrialsregister.eu/
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Learn more https://rarediseases.org/patient-assistance-programs/medicalert-assistance-program/Ensuring that patients and caregivers are armed with the tools they need to live their best lives while managing their rare condition is a vital part of NORD’s mission.
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