Female adnexal tumor of probable Wolffian origin (FATWO) often is a diagnostic challenge given its rarity, histologic heterogeneity, and lack of specific immunoprofile.


To further understand the clinicopathologic and immunohistochemical features of this rare entity.


We studied the clinical, morphologic, and immunohistochemical features of a cohort of 11 FATWO cases from our institute.


Patients' age ranged from 25 to 76 years (mean, 55 years). Tumor size ranged from 0.5 to 18 cm (mean, 2.7 cm). Histopathologically, most tumors presented with low-grade cytologic features with low mitotic activity and lack of necrosis. Three main growth patterns were appreciated: solid, tubular, and sievelike patterns. Higher-grade nuclear atypia, increased mitotic activity, and focal necrosis were seen in 2 cases. These 2 cases were clinically considered malignant FATWO mainly because of their extra-adnexal involvement. Immunohistochemical studies found that tumor cells were positive for CD10 (11 of 11, 100%), AE1/3 (8 of 8, 100%), CAM 5.2 (4 of 5, 80%), and cytokeratin 7 (CK7; 7 of 10, 70%); and focally positive for calretinin (4 of 10, 40%), inhibin (4 of 10, 40%), epithelial membrane antigen (EMA; 3 of 9, 33%), and steroidogenic factor-1 (SF-1; 2 of 8, 25%). Lack of immunoreactivity to PAX8 and GATA3 in almost all cases indicates that FATWO is different from the tumors derived from the Müllerian or mesonephric origins. All patients with available follow-up had favorable prognosis.


The broad spectrum of clinical presentation, various morphologic features, and overlapping immunophenotype suggest that FATWO is a diagnosis of exclusion until it is further defined at the molecular and immunohistochemical levels.

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Author notes

The authors have no relevant financial interest in the products or companies described in this article.