Abstract
Context: Nesidioblastosis is a rare cause of endogenous hyperinsulinemic hypoglycemia in adult population. Pancreatic neuroendocrine tumors (NET) are also uncommon among pancreatic tumors. We report a case of a young man who presented with a documented Whipple triad and was initially found to have a pancreatic cyst. Further evaluation revealed concomitant pancreatic NET and adult nesidioblastosis.
Case Description: A 36-year-old Caucasian male with history of anxiety, bipolar and seizure disorder presented with witnessed seizures and was found to have blood glucose (BG) < 20 mg/dl. He reported recurrent hypoglycemia for 3 years with recent 4-5 ER visits for hypoglycemic seizures. During a 72 hours fast study his BG dropped to 48 mg/dl after 12 hrs with the following endocrine results: Insulin 16.1 uIU/mL, C-peptide 3.02 ng/mL, Proinsulin 60.1 pmol/L, beta-hydroxybutyrate 0.08 mmol/l. BG increased to 116 mg/dl in 30 minutes after 1 mg glucagon injection. CT abdomen without contrast showed a 1.3 cm cyst in the tail of pancreas. Endoscopic ultrasonography revealed a round mixed solid and cystic mass (18x17 mm) with well-defined borders identified in the pancreas tail. FNA of the cyst reported findings consistent with a well-differentiated Neuroendocrine Tumor (NET). He underwent robotic enucleation of distal pancreatic lesions. He had recurrence of hypoglycemia 2 weeks after surgery, which did not respond to Diazoxide. He underwent distal 80 % pancreatectomy and splenectomy. Hypoglycemia resolved after the surgery. The final pathology was a well-differentiated NET WHO grade I with background neuroendocrine cell hyperplasia/nesidioblastosis.
Conclusion: Endogenous hyperinsulinemic hypoglycemia is a rare disorder with nesidioblastosis being the important cause in children and insulinoma in adults, representing a spectrum of pathologic beta cell proliferation. There are very few reports of coexistence of both conditions in adults. Our patient also had an unusual type of neuroendocrine tumor as it was cystic. The simultaneous occurrence of the two lesions offers significant challenges in diagnosis and management. The mainstay of treatment is surgical resection of insulinoma with localization of insulin hypersecretion; however, the extent of pancreatectomy in nesidioblastosis is still unclear.