Duodenal somatostatinoma with psammoma bodies: an immunohistochemical and ultrastructural study.

We report a case of malignant somatostatinoma of the ampulla of Vater in a 38-year-old woman with diabetes and cholelithiasis. Immunohistochemistry showed that tumor cells contained only somatostatin and electron microscopy revealed D-type granules in their cytoplasm. Psammoma bodies were numerous and appeared to originate in the cytoplasm of somatostatin producing cells. A review of the literature reveals that somatostatinomas with psammoma bodies are found only in the duodenum and do not produce significant amounts of peptides other than somatostatin.