Duodenal Somatostatinoma: A case report

ABSTRACT

Somatostatinoma is rare endocrine tumor that was first described in 1977 by Ganda et al. and Larsson et al. simultaneously. It seems nonfunctioning at clinical level. But it may present with diabetes, diarrhea, cholelithiasis, steatorrhea, indigestion, hypochlorhydria, and anemia. In contrast with pancreatic somatostatinoma, duodenal somatostatinoma, in general, is clinically silent. Duodenal endocrine tumors show similar histologic pattern. Therefore, the definite diagnosis is performed by immunohistochemistry and electron microscopic examination. We have experienced a case of somatostatinoma of duodenum in a 62-year-old male. He has complained generalized pruritus for one year and jaundice for 2 weeks. Grossly, the mass was a intraluminary protruding, polypoid lesion with focal mucosal erosion at immediately distal to Ampulla of Vater. Histologically, it showed tall, cylindrical cells with distinct cell membranes, having granular cytoplasm and small innocent looking nuclei. No mitosis was seen. The tumor cells were arraged in small solid groups and trabeculae, separated by fibrovascular stroma. Immunohistochemically, the tumor cells were strongly positive with somatostatin and negative with several other hormonal and neuroendocrine markers. Ultrastructurally, the cytoplasm contains numerous, homogeneous low electron dense secretory granules, which are essentially similar to those seen in normal delta cells.