Systemic treatment for coexisting mucinous urethral adenocarcinoma and prostate adenocarcinoma

Mucinous urethral adenocarcinoma is a rare and progressive cancer of the prostatic urethra. Reports on palliative systemic treatment for mucinous urethral adenocarcinoma are few. We present a case of coexisting mucinous urethral and prostate adenocarcinomas managed with systemic treatment.

A 66-year-old man presented with gross hematuria and urinary retention. Prostate-specific antigen level was elevated, at 99 ng/mL, and prostate biopsy revealed moderately to poorly differentiated adenocarcinoma. Hormone therapy and standard chemotherapy for prostate adenocarcinoma were ineffective. Prostate re-biopsy revealed coexisting mucinous urethral and prostate adenocarcinomas. Gemcitabine + cisplatin chemotherapy and folinic acid + 5-fluorouracil + irinotecan chemotherapy temporarily suppressed the cancer, but 14 months after presentation, he developed liver metastasis and died. Autopsy revealed metastasis of both mucinous urethral adenocarcinoma and carcinosarcoma.

Mucinous urethral adenocarcinoma is difficult to diagnose in coexistence with prostate adenocarcinoma. This was an extremely rare case showing chemoresistance due to epithelial-mesenchymal transition.