Hypopituitarism and nesidioblastosis in an elderly patient with orbital lymphoma

Nesidioblastosis is a rare cause of hyperinsulinemic hypoglycemia in adults. We report a case of combined hypopituitarism with secondary adrenal insufficiency and nesidioblastosis with symptomatic hypoglycemia. This 84-year-old woman had a diagnosis of right side orbital lymphoma and underwent one complete course of local radiotherapy 6 months prior to this admission. Intermittent consciousness alteration had occurred in the 2 months after radiotherapy, and hypoglycemia with a blood glucose of 0.61 mmol/L (11 mg/dL) was noted. Although this case exhibited inappropriate hyperinsulinemia during the hypoglycemic episode, the prolonged fasting test was negative, which was unusual for insulinoma but common to nesidioblastosis. The hypopituitarism and secondary adrenal insufficiency, which may have been radiotherapy related, and the nesidioblastosis led to a relapse of neuroglycopenia. After a glucocorticoid supplement and an 80% subtotal pancreatectomy, her hypoglycemic symptoms were relieved. This case reminds us that nesidioblastosis, in addition to insulinoma, should be considered as a cause of hypoglycemia in elderly patients.