Primary high-grade serous carcinoma arising in the urethra or urethral diverticulum: a report of 2 cases of an extremely rare phenomenon.

Serous carcinomas most commonly arise within the uterine corpus or ovary/fallopian tube, but there are 2 prior case reports of primary vaginal serous carcinoma. We report 2 examples of high-grade serous carcinoma arising within the urethra or a urethral diverticulum (1 case each). Both neoplasms exhibited the classic morphologic features of high-grade serous carcinoma, and a combination of clinical, radiologic, and pathologic examination excluded other possible sites of primary neoplasm.