RESUMEN
Nesidiodysplasia encompasses increased, maldistributed, and/or, improperly regulated or programmed endocrine cells associated with a clinical endocrine dysfunction. It is a frequent cause of hyperinsulinemic hypoglycemia in neonates and infants, but rare in adults. A 63 year-old woman was admitted due to the loss of consciousness and intense sweating. Hyperinsulinemic hypogiycemia was diagnosed. Under the presumptive diagnosis of insulinoma, abdominal ultrasonography and CT scan were done, but no definite tumor was found. Only a suspicious gradient in insulin concentration was found around the body of the pancreas by percutaneous portal venous sampling. While an exploratory laparotomy was performed, an intraoperative sonography was done. As a result, cystic mass like lesion was found. Then mass enucleation was done. Pathologic examination of the enucleated pancreas revealed no mass and the characteristic nesidiodysplasia. However, after the operation, hypoglycemic symptoms were repeated. So we are instructing her to eat meals frequently.