Insulinoma occurring in association with fatty replacement of unknown etiology in the pancreas: Report of a case

A 66-year-old woman with a 10-year-history of diabetes mellitus was admitte d to our hospital for investigation of several recent attacks of hypoglycem ia. Her fasting blood glucose level was very low, at 30-40 mg/dl, and abdom inal ultrasonography and computed tomography revealed a tumor in the pancre atic tail with fatty changes. Endoscopic retrograde cholangiopancreatograph y revealed absence of the main pancreatic duct from the body to tail of the pancreas. Abdominal angiography showed a hypervascular tumor stain in the pancreas, and percutaneous transhepatic portal vein sampling demonstrated a step-up of immunoreactive insulin levels in the splenic vein. Based on the se clinical findings, we made a preoperative diagnosis of an insulinoma acc ompanied by fatty changes in the pancreatic body and tail. During laparotom y for the insulinoma, fat tissue was identified in the anatomic location of the pancreatic body and tail, and resected. Pathological examination of th e resected specimen revealed a number of Langerhans islets in the adipose t issue, and an islet cell tumor with fatty replacement of the pancreatic tis sue around the tumor. The insulinoma was found not to have caused obstructi on of the main pancreatic duct. We present herein a rare case of an insulin oma that developed in the pancreas, and was associated with fatty replaceme nt of unknown etiology.