Adenocarcinoma of the urethra (including clear cell adenocarcinoma)

Adenocarcinoma of the urethra arises from the periurethral (Skene and Littre) glands or from glandular metaplasia of the urethral lining, and the WHO classification of urinary and male genital tumours separates clear cell adenocarcinoma as a distinct entity. In the defining pathology series of 19 clear cell adenocarcinomas of the urethra, 18 patients were women and one a man, aged 35 to 80 (average 58); 12 tumours, all in women, arose within a urethral diverticulum, and the tumours showed the tubulocystic, papillary and diffuse patterns with hobnail and clear cells that characterise the type (Oliva and Young 1996). The main diagnostic pitfall is nephrogenic adenoma, a benign lesion that shares clear cells and tubules (Young and Scully 1985).

How it differs from its parent: it is the histology in which women predominate, in which a urethral diverticulum is a recognised site of origin, and in which the parent's bladder-cancer and anal-cancer treatment analogies fit least well because neither urothelial chemotherapy nor squamous chemoradiation has been tested in it. Clear cell adenocarcinoma is morphologically the same tumour that occurs in the vagina and cervix, which the corpus covers on the vaginal adenocarcinoma page.

How common: no incidence figure for the type alone is published; the parent page's fewer than one case per million a year covers all urethral cancer.

Treatment follows the EAU guideline for the parent: complete surgical excision, from diverticulectomy with a margin for small tumours to anterior exenteration for advanced disease, with radiotherapy for positive margins; systemic therapy has no evidence base of its own and is chosen case by case (EAU Guidelines: primary urethral carcinoma; NCI PDQ).