MEN I Associated Insulinoma and Zollinger Ellison Syndrome Presenting with Syncope

Abstract

Purpose: A 24-year-old woman with a history of prolactinoma, neurofibromas and parathyroid hyperplasia reported a 3-month history of fainting episodes. She was found to have a FS glucose <30, an elevated serum insulin of 130 mU/ml, a normal C-peptide and CT scan revealed an enhancing 3.4-cm pancreatic body lesion. An insulinoma was suspected and the patient had a subtotal pancreactectomy with pathology identifying a 3.5-cm well-differentiated neuroendocrine tumor and two smaller 1.5- and 0.5-cm nodules in the pancreatic tail all with immunostaining positive for insulin and negative for PTH and gastrin, consistent with Beta cell tumor. The patient had persistent JP drain output concerning for a pancreatic duct leak. ERCP was performed which was notable for LA class C distal esophagitis, clean based fundic ulcer and multiple clean based duodenal ulcers including a large 2-cm ulcer adjacent to the ampulla. Serum gastrin level was elevated at 3,324 pg/ml, consistent with Zollinger-Ellison Syndrome with a constellation of findings suggestive of multiple neuroendocrine neoplasm I (MEN I). The diagnosis of insulinoma is often delayed due to the non-specific symptoms. Nearly 90% of insulinomas are solitary, benign and less than 1.5 cm in diameter. However, those associated with MEN I are usually multiple. Reports indicate CT imaging can identify tumors less than 1 cm with a sensitivity of 40-73% and MRI increases that number to 85-95%. EUS can identify lesions as small as 5 mm with sensitivity approaching 95%. This patient's presentation and history suggested MEN I in which efforts to identify the more aggressive, multiple lesions could be made utilizing EUS. We recommend further studies evaluating the role of pre-operative EUS tumor localization in suspected MEN I associated neuroendocrine tumors.Figure: Enhancing mid pancreatic lesion.Figure: [776] Pathology specimen demonstrates pale 3.5 cm mass in the pancreatic body.