Clear cell adenocarcinoma of the urethra: evidence for origin within paraurethral ducts.

We report a case of clear cell adenocarcinoma arising in a paraurethral duct treated by anterior pelvic exenteration. Immunohistochemical stains for prostate specific acid phosphatase and prostate specific antigen were positive in the primary tumor and regional metastases. Focal positive staining also was noted in normal paraurethral duct epithelium. Our observations suggest that clear cell adenocarcinoma arises from the female paraurethral ducts, rather than embryonic remnants. These ducts appear to be homologous to the prostate and in some cases may be misinterpreted as urethral diverticula.