Zollinger-Ellison syndrome (ZES) is a rare disorder that causes tumors in the pancreas and duodenum and ulcers in the stomach and duodenum. The pancreas is a gland located behind the stomach. It produces enzymes that break down fat, protein, and carbohydrates from food, and hormones like insulin that break down sugar. The duodenum is the first part of the small intestine.
The tumors secrete a hormone called gastrin that causes the stomach to produce too much acid, which in turn causes stomach and duodenal ulcers (peptic ulcers). The ulcers caused by ZES are less responsive to treatment than ordinary peptic ulcers. What causes people with ZES to develop tumors is unknown, but approximately 25 percent of ZES cases are associated with a genetic disorder called multiple endocrine neoplasia type 1, which is associated with additional disorders.
The symptoms of ZES include signs of peptic ulcers: gnawing, burning pain in the abdomen; diarrhea; nausea; vomiting; fatigue; weakness; weight loss; and bleeding. Physicians diagnose ZES through blood tests to measure levels of gastrin and gastric acid secretion. They may check for ulcers by doing an endoscopy, which involves looking at the lining of the stomach and duodenum through a lighted tube.
The primary treatment for ZES is medication to reduce the production of stomach acid. Proton pump inhibitors that suppress acid production and promote healing are the first line of treatment and include lansoprazole, omeprazole, pantoprazole, and rabeprazole. H-2 blockers such as cimetidine, famotidine, and ranitidine may also be used, but are less effective in reducing stomach acid. Surgery to treat peptic ulcers or to remove tumors in the pancreas or duodenum are other treatment options. People who have been treated for ZES should be monitored in case the ulcers or tumors recur.
source: http://digestive.niddk.nih.gov/ddiseases/pubs/zollinger/index.htm