Management of islet cell tumors in patients with multiple endocrine neoplasia: a prospective study

As part of a study to manage islet cell tumors in patients with multiple endocrine neoplasia (MEN), patients with MEN I and Zollinger-Ellison syndrome (ZES) underwent surgery if a pancreatic islet cell tumor was identified on imaging studies. Patients with MEN I and either insulinoma or vasoactive intestinal polypeptide tumor (VIPoma) underwent surgery whether or not a tumor was identified. Each patient underwent preoperative portal venous sampling (PVS). Nine patients with MEN I and one with MEN II underwent surgery; seven had ZES, one had insulinoma, one had VIPoma, and one had both insulinoma and ZES. Eight of the nine patients with MEN I had an identifiable hormone gradient on PVS. Islet cell tumors were removed from the pancreas of each patient; two patients also had duodenal wall tumors, and three patients had malignant islet cell tumors. No patient with ZES and MEN I was cured of ZES despite the fact that islet cell tumor was removed from the region of the gastrin gradient in five of six patients. The single patient with MEN II and ZES and the three additional patients with MEN I and either insulinoma or VIPoma were cured by islet cell tumor resection. The results indicate that islet cell tumors in patients with MEN I can be both extrapancreatic and malignant. In patients with MEN I and ZES, ZES cannot be cured by tumor resection, and PVS cannot be used to select patients for curative surgery. It appears that gastrinoma in patients with MEN II, as well as either insulinoma or VIPoma in patients with MEN I, can be cured by islet cell tumor resection.