Zollinger-Ellison syndrome is an uncommon condition caused by a gastrinoma, a type of tumor that typically forms in the pancreas. This tumor releases the hormone gastrin, which triggers excessive acid production, resulting in severe ulcers in the stomach and upper parts of the small intestine, such as the duodenum. Gastrinomas linked to Zollinger-Ellison syndrome can also be found in the stomach, duodenum, and lymph nodes, not just in the pancreas.To manage Zollinger-Ellison syndrome, medications like H2 antagonists (such as cimetidine, known by the brand name Tagamet, and ranitidine, or Zantac) and proton pump inhibitors (such as lansoprazole, marketed as Prevacid, and omeprazole, or Prilosec) are used. H2 antagonists work by blocking the action of histamine on stomach cells, thereby decreasing acid production. Proton pump inhibitors, on the other hand, directly inhibit acid production in these cells and are more effective than H2 antagonists, often requiring high doses. Surgical removal of the gastrinoma can cure about 25% of affected individuals.The syndrome is named after two American surgeons, Robert M. Zollinger (1903-1992) and Edwin H. Ellison (1918-1970).