Primary carcinoid tumor of the urinary bladder

A polyp of about 1.0 cm diameter was incidentally found at the center of theposterior wall of the urinary bladder in a 73-year-old man on cystoscopicexamination. A polyp was resected through a transurethral route withoutrecurrence for 22 months. A polyp consisted of a tumor covered with mucosaof the bladder. Tumor cells have round or oval nuclei with fine chromatinand one or two nucleoli per nucleus, and finely granular eosinophiliccytoplasm, being arranged in a trabecular or tubular pattern. Furthermore,they showed positive staining for chromogranin-A and with Grimelius stain,indicating that the tumor is a carcinoid tumor. Since there was no evidenceof carcinoid tumors in organs other than the urinary bladder, the presentcase is a primary carcinoid tumor (well differentiated endocrine tumor) ofthe urinary bladder which is extremely rare.