Tubulocystic clear cell adenocarcinoma arising within the prostate.

Neoplasms resembling ovarian common epithelial-type tumors, including clear cell adenocarcinomas, rarely occur in the lower urinary tract of men. When they do, they develop in the urethra or urinary bladder. We report a case of such a tumor arising within the prostate of a 47-year-old man. The tumor was a cystic mass in the left posterolateral region of the prostate. Histologically, the tumor was chiefly composed of tubulocystic and papillary glands lined by glycogen-rich, cuboidal or hobnail cells with clear to eosinophilic cytoplasm. The tumor cells were strongly positive for pan-cytokeratin, low molecular weight cytokeratin, and epithelial membrane antigen, and focally positive for high molecular weight keratin. The tumor did not immunohistochemically express prostate-specific antigen (PSA) and prostatic acid phosphatase. Serologically, the patient had increased levels of CA125 instead of PSA. The clinical as well as the pathologic features are consistent with a clear cell adenocarcinoma as seen in the female genital tract rather than a typical prostatic adenocarcinoma.