Prostatic urothelial-type
adenocarcinoma arises through a process of glandular
metaplasia of the prostatic urethral urothelium and subsequent
in situ adenocarcinoma sometimes associated with
villous adenoma. These prostatic
adenocarcinomas are analogous to nonurachal
adenocarcinomas arising in the bladder from
cystitis glandularis. Only 2 cases of urothelial-type
adenocarcinoma from an institution other than our own have been previously described. The distinction between
adenocarcinoma from another organ secondarily involving the prostate, usual
adenocarcinoma of the prostate, and prostatic urothelial-type
adenocarcinoma can present a significant diagnostic challenge and has significant therapeutic implications. Fifteen cases of prostatic urothelial-type
adenocarcinoma were retrieved from the consult files of one of the authors. Mean patient age at diagnosis was 72 years (range 58 to 93 y). All men had negative colonoscopies, clinically excluding a colonic primary. Bladder primaries were ruled out clinically or pathologically in radical resection specimens. Follow-up was available on all men with a mean of 50.3 months (range 2 to 161 mo). All men presented with urinary obstruction symptoms with 3 (20%) also having mucusuria and 2 (13.3%) also having
hematuria. Four men (26.7%) developed metastatic disease and 8 (53.3%) died of disease. In 8/15 (53%) cases, glandular
metaplasia of the prostatic urethra and contiguous transition to
adenocarcinoma were identified. Multiple histologic patterns were observed including dissection of the stroma by
mucin pools 15/15 (100%), villous features 7/15 (47%),
necrosis 2/15 (13.3%), signet ring cells 3/15 (20%), perineural invasion 1/15 (6.7%), focal squamous differentiation 1/15 (6.7%), and a granulomatous inflammatory response 1/15 (6.7%). Immunohistochemical stains were negative for
prostate specific antigen, prostate specific
acid phosphatase, CDX2, and
beta-catenin in all cases. Stains were positive for high molecular weight
cytokeratin in 12/12 cases (100%), and CK7 and CK20 in 10/12 cases (83.3%). Prostatic urothelial-type
adenocarcinoma is a rare aggressive
cancer arising in the prostate. The differential diagnosis includes conventional prostatic
mucinous adenocarcinoma and secondary infiltration from a colonic or bladder
adenocarcinoma. Immunohistochemistry for
prostate specific antigen, prostate specific
acid phosphatase, and high molecular weight
cytokeratin along with morphology can help rule out conventional prostate
carcinoma.
beta-catenin, CDX2, and clinical studies are needed to rule out colonic
adenocarcinoma. As prostatic urothelial-type
adenocarcinoma is entirely analogous to bladder
adenocarcinoma in both, its morphology and immunophenotype, only clinical studies or in some cases pathologic examination of the cystoprostatectomy specimen can exclude infiltration from a primary bladder
adenocarcinoma.