Ampullary somatostatinoma in a patient with Merkel cell carcinoma.

A 59-yr-old white man with Merkel cell carcinoma of his right leg status post extensive skin resection and chemotherapy had dilated hepatic and common bile ducts on a routine follow-up abdominal CT scan. A 1.9-cm ampullary mass was appreciated on endoscopy. Histology showed psammoma bodies and positive immunoperoxidase staining consistent with a somatostatinoma. Merkel cell tumors and somatostatinomas are extremely rare neuroendocrine tumors derived from neural crest cells. Associations have been found between somatostatinomas and other islet cell tumors with multiple endocrine neoplasia syndromes, but no reported association has been published between islet cell tumors and Merkel cell tumors. This patient represents the first documented case of Merkel cell carcinoma and somatostatinoma in a single patient. Such an occurrence may represent a previously undescribed neuroendocrine tumor syndrome, and this possibility should be considered when either tumor is diagnosed.