Endocrine Abstracts

Duodenopancreatic neuroendocrine tumours (dpNETs) affect more than 90% of patients with Multiple Endocrine Neoplasia type 1 (MEN1) by age of 70. Insulinomas are the second most common functioning dpNET encountered in this setting. We present the case of a 56 year-old woman with genetically confirmed MEN1 in whom non-functioning pNETs transformed into insulinomas, seven years after being diagnosed with MEN1 syndrome and pNETs. The patient was referred to the neuroendocrine clinic following the detection of an incidental pancreatic lesion on abdominal imaging. This occurred on a background of primary hyperparathyroidism, previously managed by parathyroidectomy. At the diagnosis, Endoscopic ultrasound (EUS) confirmed multiple small pNETs, one located in the head of the pancreas and several in its body and tail with multiple areas of enterochromaffin-like cell (ECL) hyperplasia. Surveillance EUS was performed 2-yearly over a 6 year period and showed stable pNETs. There were no symptoms to suggest a functioning pNET over this initial time period. The following year however, the patient was admitted to hospital following a severe hypoglycaemic episode (capillary blood glucose <2 mmol/l), and commenced diazoxide. A 72-hour fast showed a nadir serum glucose of 2.5 mmol/l (insulin and c-peptide results were non-diagnostic as performed shortly after stopping diazoxide). Interval EUS showed an 11mm pNET in the isthmus and 2 smaller pNETs in the body and tail of the pancreas with multiple areas of ECL hyperplasia. Selective intra-arterial calcium injection test was positive and localised to the proximal gastroduodenal and proximal splenic arteries. 3 pNETs were successfully enucleated, 2 of which were histologically proven insulinomas. This resulted in a significant reduction in the burden of hypoglycaemia. Although uncommon, non-functional pNETs have the potential to transform into a functional syndrome in MEN1. Further research is required to predict risk factors and mechanisms of transformation in pNETs.