Gastric carcinoid tumors.

Initially, carcinoid tumors were a curiosity for physicians and were so named because of their relatively benign behavior as compared to the more common adenocarcinomas. As medicine has evolved, our understanding and management have greatly improved. Our classification system has also become more specific. Gastric carcinoid tumors are unique in that three types have been described based upon each one's pathophysiology. In general, none of these give rise to the typical carcinoid syndrome as seen with metastatic ileal carcinoids.Type 1 gastric carcinoids represent 70% to 80% and are characterized by multiple small lesions and their association with hypergastrinemia secondary to chronic atrophic gastritis and pernicious anemia, and are less likely to metastasize. Type 2 is a rare entity, representing 5%, and is characterized by multiple small lesions, hypergastrinemia secondary to Zollinger-Ellison syndrome, and multiple endocrine neoplasia (MEN) type 1. The risk for metastasis is slightly higher than for type 1; however, overall prognosis is dependent upon the gastrinoma prognosis. Accounting for 20%, type 3 is known as sporadic gastric carcinoids in that there is no association with hypergastrinemia, chronic atrophic gastritis, or Zollinger-Ellison syndrome. These present as large solitary lesions and are often metastatic upon diagnosis. A unique feature of type 3 is its association with an atypical carcinoid syndrome that is thought to be mediated by histamine.The treatment-including medical, endoscopic, and surgical-of gastric carcinoids is dictated by the type, size, and presence of metastasis.