Islet cell hyperplasia of the pancreas presenting as hyperinsulinemic hypoglycemia in an adult

A 72-year-old man who had suffered several episodes of syncope was diagnose d as having hyperinsulinemic hypoglycemia. Although imaging studies and per cutaneous transhepatic portal venous sampling did not reveal the existence of any tumors in the pancreas, distal pancreatectomy was performed because the possibility of a small pancreatic endocrine tumor could not be complete ly rejected. External examination of the surgically removed pancreas did no t reveal any tumors. Microscopically, the pancreas exhibited diffuse islet cell hyperplasia without nesidioblastosis. The patient remains euglycemic a nd has tolerated 24-hour fasting without any medication for a period of 10 months after the operation.