Islet cell tumor arising from a heterotopic pancreas in the duodenal wall with ulceration.

A rare case of symptomatic islet cell tumor arising from heterotopic pancreas in the duodenum with ulceration is described. Gastrointestinal bleeding was the only sign observed in this patient. Tagged red blood cell scan, upper endoscopy, and computed tomography scan showed active bleeding ulcer from a periampullary mass. Removal of the submucosal tumor was done to prevent future re-bleeding. Histologic and immunohistochemical characterization of the tumor showed an endocrine tumor that expressed a variety of endocrine peptides.