Zollinger-Ellison Syndrome:

 

ZES is caused by the uncontrolled secretion of abnormal amounts of gastrin by a duodenal or pancreatic neuroendocrine tumor (i.e., gastrinoma). Most cases (80%) are sporadic, but 20% are inherited. The inherited or familial form of gastrinoma is associated with multiple endocrine neoplasia type 1 (MEN1), which consists of parathyroid, pituitary, and pancreatic (or duodenal) tumors. Gastrinoma is the most common pancreatic tumor in patients with MEN I.