[A CASE OF SMALL CELL CARCINOMA IN A DIVERTICULUM OF THE BLADDER].

An 80-year-old man was referred to our hospital with a complaint of acute urinary retention due to hematuria. Cystoscopy revealed a broad-based tumor arising in a diverticulum on the right lateral wall of the bladder. Transurethral resection of the bladder tumor (TURBT) was performed immediately. The pathological diagnosis was small-cell carcinoma without any urothelial carcinomas, and clinical examination revealed a clinical stage of T3b, N0, M0. Thus, 3 courses of neoadjuvant chemotherapy with cisplatin and irinotecan were administered. Chemotherapy resulted in tumor shrinkage, and partial cystectomy was performed under a diagnosis of stage pT3aN0M0 bladder cancer in the diverticulum. The patient is alive without any evidence of tumor recurrence at 13 months after the operation. To our knowledge, this is the first case report in Japan of small-cell carcinoma in a diverticulum of the urinary bladder, for which partial cystectomy was performed after chemotherapy.