Skene's gland adenocarcinoma with intestinal differentiation: A case report and literature review.

Adenocarcinoma of Skene's gland (the female homolog to the male prostate) is extremely rare, with only a few cases reported. We present a case of Skene's gland adenocarcinoma with intestinal differentiation. The patient was a 69-year-old Japanese woman who was operated on for a recurrent tumor of the external ostium of the urethra. Histopathologically, the tumor showed glandular and cribriform patterns with a signet-ring cell component in a mucus lake. Immunohistochemically, the tumor cells were positive for prostate specific acid phosphatase (PSAP), and AMACR, and negative for Nkx3.1 or prostate specific antigen (PSA). Although in situ lesion could not be discovered, positive immunostainings for Nkx3.1, PSAP, and androgen receptor in the remaining paraurethral glands around the tumor indirectly but strongly suggest that the tumor had originated from Skene's gland. This tumor also showed intestinal differentiation as suggested histologically and by positive immunostainings for CDX2, MUC2, and CK20, along with negative immunostaining for CK7. It is often very difficult to identify the origin of a female urethral carcinoma. In such cases, immunohistochemical features can be an essential clue to the origin. We therefore present this instructive case with a literature review.