A Case of Pancreatic Insulinoma in which the Tumor was Difficult to Localize Preoperatively

Abstract

Some insulinomas are difficult to localize preoperatively and the tumors are often multiple. Herein, we report a case of pancreatic insulinoma in which preoperative localization proved difficult. The patient was a 37-year-old woman who presented with a history of frequent attacks of hyperhidrosis and consciousness disturbance. She was diagnosed as having insulinoma, however, imaging studies failed to enable localization of the tumor. Then, we performed a selective arterial calcium injection test, in which insulin uptake was recognized in the splenic artery and transvers pancreatic artery branching from the gastroduodenal artery. Based on the findings, we estimated that the tumor was localized in the dorsal pancreatic area. We performed distal pancreatomy with intraoperative intermittent insulin monitoring. After resection of the tumor-feeding arteries, we recognized both fall of the insulin levels and elevation of the blood sugar levels. Histopathological examination revealed the diagnosis of pancreatic neuroendocrine tumor (G1, insulinoma). We could estimate that the tumor might be localized in the dorsal pancreas by performing a preoperative SACI test. In addition, intraoperative insulin monitoring was useful for the tumor resection.