Figure 1. Distribution of primary duodenal and pancreatic neuroendocrine tumors in 21 patients with multiple endocrine neoplasia type 1. Two gastrinomas were located in the duodenal wall. The intrapancreatic tumors demonstrated an even distribution according to the approximate volume of parenchyma in each pancreatic region. Maximum diameter of largest tumor: N = 39; range 0.1–8.0 cm; mean 1.83 cm.