Endocrine Abstracts

Somatostatinomas are rare neuroendocrine tumors of the pancreas and small intestine that can occur sporadically or in a syndromic form. Duodenal somatostatinomas are often associated with neurofibromatosis type1 (NF1). Their presenting features are mostly related to local effects of the tumor mass rather than functional clinical syndrome. Nesidioblastosis is extremely rare cause of persistant hyperinsulinemic hypoglycaemia in adults.

We present a case of a 34-year-old woman with NF1 admitted to our hospital for evaluation two months after pylorus-preserving-duodenopancreatectomy and cholecystectomy for incidental perioperative finding of multiple duodenal tumors. Preoperative abdominal MSCT showed dilatation of extrahepatic bile ducts and cholelithiasis and it was initial indication for the surgery. In the previous year she had occasional episodes of hunger, tremor and sweating that dissapeared after food intake. Pathohistology revealed three well-differentiated periampullar neuroendocrine tumors with identical histological and immunohistochemical features (CgA+, Syn+, SMS+, Ki-67 4%, p53 9%, proinsulin <1% cells), with psammoma bodies and regional lymph nodes metastases (2 out of 31 lymhnodes positive). The histopathological study of the resected pancreatic tissue revealed nesidioblastosis. Postoperatively prolonged OGTT (5-h test, glucose 75 g) revealed normal glucose response without hypoglycemia. Hypoglycemia did not occur during 72-h fast, although low plasma glucose level was detected (2.9 mmol/l) with inappropriate insulin level (16.7 mIU/l). During the euglycemic hyperinsulinemic clamp study, plasma C-peptide levels declined from 1.1 to 0.48 nmol/l, indicating supression of endogenous insulin secretion. Octreoscan (99mTc-tektreotide) was negative. Chromogranin-A was in the normal range. In conclusion ampullary somatostatinomas associated with NF1, usually are not associated with somatostatinoma syndrome, although diabetes and cholelithiasis have occasionally been described. Somatostatin exerts inhibitory influence on insulin secretion. But even after successful surgery for somatostatinomas no overt hypoglycaemic episodes were noted in our patient in spite of nesidioblastosis.