A rare case of carcinoid tumor arising in the duodenum is reported. It was found unexpectedly at the time of gastrojejunostomy on a female patient aged 73 years who had suffered from gastric ulcer. The patient has been free from any manifestation of malignant carcinoid syndrome and has now been alive half a year.
The tumor is located mainly in the submucosa and showed infiltrative invasion into the muscle coat and the subserosal tissue. The tumor contained a small number of argentaffin tumor cells. Histopathologically and histochemically this tumor was identified as argentaffinoma (carcinoid)
