Diagnosis of pancreatic islet hyperplasia causing hypoglycemia in a patient with portacaval anastomosis.

A patient with biopsy-proved biliary cirrhosis and previous gastrojejunostomy and portacaval anastomosis experienced episodes of severe hypoglycemia. She was found to have hyperinsulinemia and hyperglucagonemia. An oral glucose tolerance test showed postgastrectomy hypoglycemia. Results of the intravenous tolbutamide test were diagnostic for insulinoma, but results of the intravenous glucagon test and prolonged fast (96 hours) were not. Failure, on two occasions, to suppress C-peptide normally during insulin-induced hypoglycemia led to a diagnosis of pancreatogenous hyperinsulinemia. The pancreas showed a 10-fold increase in islet volume, with intensely positive staining with anti-insulin and anti-glucagon antiserums in addition to anti-somatostatin and anti-pancreatic polypeptide antiserums. Incidental findings at pancreatic exploration were a mesothelioma, which did not stain with anti-insulin antiserum, and, at autopsy one year later, a hepatoma.