Nesidioblastosis with hyperinsulinemic hypoglycemia in adults: report of two cases.

We report herein the cases of two women, aged 34 years and 39 years, respectively, found to have hyperinsulinemic hypoglycemia after presenting with a history of episodes of temporary loss of consciousness, nausea, and fainting. Under the suspected diagnosis of insulinoma, localization procedures were carried out, but no tumor was found. In both patients, a definite gradient in insulin concentration was found in the pancreas by percutaneous transhepatic or intraoperative portal venous sampling, and a misdiagnosis of insulinoma of the pancreatic body was made. During exploratory laparotomy no tumor was palpable in the pancreas, and intraoperative ultrasonography showed no low echoic mass in the pancreas. A distal pancreatectomy was performed in both patients, and histopathological examination of the resected specimens revealed graded slight hyperplasia of the islet cells.