Minute carcinoid tumor of the gallbladder.

A minute carcinoid tumor of the gallbladder is reported. The tumor was incidentally identified in a 77-year-old Japanese man with cholecystolithiasis, hepatocellular carcinoma and sigmoid colon carcinoma. The tumor formed a 5-mm-sized sessile polyp at the neck of the gallbladder. The tumor cells, which were argyrophilic and non-argentaffinic, belonged to the foregut-type. Immunohistochemically, they were positive for neuron-specific enolase (NSE) and somatostatin.