Clinically Adult-Onset Nesidioblastosis with Repeated Severe Hypoglycemia, Successfully Treated by Two Times Pancreatectomies. A Rare Case Report.

Although nesidioblastosis is the most common cause of hyperinsulinemic hypoglycemia in infants, it is rare in adults. Nesidioblastosis is pathologically characterized by diffuse neoformation of the islets of Langerhans islets from the pancreatic ductal epithelium and is a disease that does not exhibit neoplastic proliferation, unlike insulinoma. Hence, we present a rare case of adult-onset nesidioblastosis that caused repeated severe hypoglycemic symptoms and was cured by pancreatic resection twice, resulting in total pancreatectomy. A 37-year-old woman with the Whipple's triad visited our institution. In the fasting test, the plasma glucose level decreased and immunoreactive insulin levels increased after 12 h. No tumor was identified in the pancreas by imaging. A selective arterial calcium injection test revealed that step-up was detected only in the gastroduodenal artery. The patient underwent pancreatoduodenectomy with a diagnosis of adult-onset nesidioblastosis, with the pancreatic head region as the culprit. Pathological examination revealed neither tumorous islet cells nor an obvious increase in the number of islets. However, there were some isolated single insulin-producing cells in the pancreatic parenchyma, which could cause hyperinsulinemia and hypoglycemia. This patient was diagnosed with adult-onset nesidioblastosis. After the operation, the hypoglycemic symptoms improved, but 1 year later, the same symptoms recurred. The patient underwent remnant pancreatectomy and had no hypoglycemic symptoms for > 5 years after the second surgery.