Rare Tumors of Wolffian Duct Origin: Clinical Insights from a FATWO Case and Literature Overview

The term Female Adnexal Tumor of Probable Wolffian Origin (FATWO) was first introduced by Kariminejad and Scully in 1973 [1]. Later studies supported the Wolffian duct origin of these tumors using immunohistochemical and electron microscopy methods [2]. Although mitotic activity and capsular invasion were observed, the tumor was initially classified as benign [2].

FATWO is an extremely rare neoplasm of the female reproductive tract, thought to arise from remnants of the mesonephric (Wolffian) duct—embryological structures that are anatomically independent from Müllerian derivatives. These remnants are most commonly located in the broad ligament but can also be found in the mesosalpinx, fallopian tubes, ovaries, or omentum [2,3]. In most cases, FATWO is asymptomatic and discovered incidentally during imaging or surgical procedures performed for unrelated reasons. Some patients, however, may present with abdominal pain or a palpable mass [3]. The age of onset ranges from 15 to 83 years, with a median age of diagnosis around 50 [3]. Although the majority of FATWO cases exhibit benign clinical behavior, approximately 11% may show disease progression within two years of diagnosis [4]. Recurrent or metastatic behavior has been documented, suggesting a low malignant potential in some cases [4]. To date, no standardized treatment protocols exist for recurrent or metastatic FATWO [2]. This study presents a rare clinical case of FATWO and aims to contribute to the limited body of literature regarding its diagnostic challenges and management approaches.

2.Materials and Methods

Patient Information

A 57-year-old non-smoking, married female was referred to a specialized oncology center following the incidental discovery of a right ovarian tumor during routine evaluation. Her medical history included thyroid resection for nodular goiter, appendectomy, and laparoscopic myomectomy in 2014. The patient was postmenopausal for three years at the time of presentation.

Laboratory Evaluation

All serum tumor markers were within reference ranges: CA-125 - 22.32 U/mL, HCE - 12.35 ng/mL, AFP - 1.57 ng/mL, β-hCG - 6.83 mIU/mL, HE4 - 56.14 pmol/L. The ROMA index was calculated as 9.8% in premenopausal and 16.41% in postmenopausal settings.

Imaging Studies

Multislice computed tomography (MSCT) and pelvic magnetic resonance imaging (MRI) revealed multiple dense implants up to 15 mm along the uterine ligaments, pelvic peritoneum, and hypogastric region (Figure 1). A large cystic-solid mass measuring 102×119×72 mm was visualized separately from the ovaries, with a heterogeneous internal structure and clearly demarcated borders. T2-weighted imaging demonstrated mixed high- and low-intensity signal regions (Figure 2).

Surgical Procedure

The patient underwent total abdominal hysterectomy with bilateral salpingo-oophorectomy, pelvic peritonectomy, omentectomy, and resection of metastatic lesions from the sigmoid mesentery and anterior abdominal wall. Intraoperatively, the uterus was normal in shape and measured 8×6×5 cm; adnexa appeared macroscopically unremarkable. A retroperitoneally extending tumor-like mass measuring 12×10×7 cm was identified anterior to the uterus and bladder. Additional nodules were detected in the Douglas pouch (3×4 cm), on pelvic peritoneum, sigmoid mesentery (up to 3 cm), anterior abdominal wall, and greater omentum (up to 1 cm) (Figure 3). Complete primary cytoreduction was achieved.

Macroscopic Pathology

The tumor had an uneven, lobulated surface and a cystic-solid consistency. Hemorrhagic fluid was present in cystic spaces, while the solid areas were grey-white to grey-yellow (Figure 4).

Histopathological Analysis

Histological examination of the main tumor and peritoneal, mesenteric, omental, and abdominal wall deposits revealed a uniform morphology. The tumor was composed of tubular structures with slit-like lumina, along with trabecular and solid growth patterns. The stroma was composed of hyalinized and sclerotic connective tissue (Figure 5). Tumor borders were well-defined, with no evidence of infiltrative growth. The ovarian parenchyma was uninvolved, and the tumor was separated from it by a thin fibrous pseudocapsule (Figure 6).

Cytology and Immunohistochemistry

Tumor cells exhibited minimal cytological atypia and were predominantly cuboidal to columnar in shape. Some elongated cells had indistinct cell borders. Cytoplasm was eosinophilic or vacuolated; nuclei were round to oval with smooth contours and fine chromatin. Nucleoli were inconspicuous, and mitotic figures were not observed (Figure 7).

Immunohistochemical profiling revealed strong, diffuse expression of vimentin, pancytokeratin, and WT1; focal weak expression of α-inhibin and calretinin; and nuclear progesterone receptor expression in isolated cells (Figure 8). Tumor cells were negative for CK7, CK5/6, CK20, PAX8, CD10, CD117, EMA, ER, GATA3, EpCAM, D2-40, HMW, CD34, CD99, CD56, chromogranin A, synaptophysin, Melan-A, and β-catenin. The Ki-67 proliferation index was <1% (Figure 9).

Additional Findings

Examination of the uterus revealed endometrial glandular hyperplasia without atypia and a uterine wall intramural leiomyoma. Pelvic lymph nodes were free of metastases but contained areas of endosalpingiosis. Both fallopian tubes and one ovary were not involved by the tumor.