Male adnexal tumor of probable Wolffian origin: a new entity in males similar to female adnexal tumor of probable Wolffian origin.

Female adnexal tumor of probable Wolffian origin is a rare tumor listed in the 2016 WHO classification of the female reproductive tract. It does not have a WHO-recognized counterpart in the male urogenital tract. However, some cases of male adnexal tumors have been described in the literature. We present the case of a 41-year-old male who presented with a 2-cm nodule in the testicle. LDH, HCG, and AFP blood levels were normal. Gross examination showed an intratesticular, whitish, microcystic, firm, and encapsulated nodule of 2 cm. Microscopically, the tumor was well circumscribed, solid, and microcystic. In the solid areas, cells were fusiform or polygonal with an eosinophilic pale cytoplasm and a regular oval nucleus. Cysts were surrounded by a fibromuscular stroma and lined by a single layer of cylindrical epithelium, with apical cilia. On immunohistochemistry, tumor cells expressed AE1/AE3 and vimentin and were negative for calretinin, epithelial membrane antigen (EMA), and inhibin. All the differential diagnoses at this localization being ruled out, the tumor was compared to a female adnexal tumor of probable Wolffian origin. Both tumors had approximately the same morphological and immunohistochemical profile. Naming our tumor MATPWO is therefore justified, but it remains of a probable origin because further studies need to be performed in order to certify this hypothesis.