Endocrine Abstracts

Introduction: Persistent hyperinsulinemic hypoglycemia may be caused either by a solitary tumor of the pancreas secreting excessive amount of insulin, known as insulinoma or, rarely, by nesidioblastosis. Nesidioblastosis is a rare cause of persistent hyperinsulinemic hypoglycemia in adults.

Methods: We describe the case of a 25-year-old male patient who was referred to our clinic for repeted hypoglycemia episodes.

Results: Our patient described several fasting episodes of hypoglycemia (less than 30 mg/dl) in the past months. Coinciding with these episodes he presented trembling and sweating. He had been diagnosed with epilepsy 2 years earlier and was taking treatment with levetiracetam and valproic acid. He had gained 12 Kilos recently. We performed a 72-hour-fasting test with confirmation of endogenous hypoglycemia after 6 hours of fasting. Suspecting an insulinoma we performed several imaging tests with negative results (somatostin receptors scintigraphy, CT scan, MRI, echoendoscopy and 18F-DOPA PET/CT). The patient also underwent 2 intra-arterial selective calcium test procedures observing increased insulinemia levels in superior mesenteric artery and splenic artery. He was in the meantime taking diazoxide for controlling hypoglycemia with improvement in the number and severity of hypoglycemia episodes but with poor gastro-intestinal tolerance of this medication. Finally we performed an exploratory laparotomy with pancreatic palpation and ultrasound and pancreatic biopsy analysis showing pancreatic tissue with mild increase, in size and number, of islets, compatible with islet hyperplasia B. In a second time the patient underwent corporo-caudal pancreatectomy confirming the suspected diagnosis of pancreatogenous hypoglycemia non-insulinoma (nesidioblastosis of the adult). After surgery our patient has not presented new hypoglycemia episodes and has a good glycemic control.

Conclusion: Nesidioblastosis is a very rare disease of difficult diagnosis but it should be considered in all cases of failure to locate an insulinoma, as this may be presented in up to 4% of persistent hyperinsulinemic hypoglycemia.