Clear cell adenocarcinoma of the female urethra. A case report.

A case of urethral clear cell adenocarcinoma (mesonephric carcinoma) in a 62-year-old woman is reported. The patient consulted our hospital because of acute urinary retention. Fine needle aspiration cytology showed a few atypical cells; loose cluster cells with finely vacuolated cytoplasm, large nuclei and prominent nucleoli, and small cluster cells with finely vacuolated, delicate cytoplasm, small pale nuclei and small nucleoli. Cytologic diagnosis was adenocarcinoma and no diagnosis of clear cell adenocarcinoma was obtained. The neoplasia was localized at the posterior wall of the urethra and deep muscular layer of the vaginal wall. Histologically, the tumor revealed mainly small, elongated glands consisting of single-layered cuboidal or columnar cells with scanty cytoplasm and a focally hobnail appearance. In addition, a small cystic lesion resembling nephrogenic adenoma was observed. This finding raises the possibility that clear cell adenocarcinoma may be a malignant counterpart of nephrogenic adenoma.