Nesidioblastosis of the pancreas in an adult with persistent hyperinsulinemic hypoglycemia

The rare finding of pancreatic nesidioblastosis in an adult is described. A 43-year-old woman presented with a two-year history of hypoglycemic hyperinsulinism. Extensive diagnostic procedures revealed no insulinoma. Subtotal (75%) pancreatectomy relieved her symptoms; she has normal insulin levels 2.5 years after surgery. The pancreatic specimen revealed only discrete islet cell abnormalities, namely B-cells budding off ductular epithelium, islets in apposition to ducts, slight islet cell hypertrophy, and islet enlargement. Immunohistochemistry showed normal total endocrine cell content as well as normal proportions of islet cell subpopulations. Review of 20 cases in the literature and the authors' experience led to subtotal (75-90%) pancreatectomy as the treatment of choice. The authors conclude that the pediatric disease of nesidioblastosis may rarely occur in adults and that the paucity of histologic findings makes the exclusion of an insulinoma mandatory.