Carcinoid tumors.

Carcinoid tumors, which arise from the enterochromaffin cells of the gastrointestinal tract, encompass a diverse group of neoplasms. Once thought to be "carcinoma-like," these neoplasms exhibit a biologic behavior that varies from an indolent, benign course to an aggressive, rapidly progressive, and deadly disease. Today the term carcinoid is reserved for neuroendocrine tumors arising from the small bowel or neuroendocrine tumors that can cause carcinoid syndrome. This newer terminology has yet to be universally adopted, adding to the confusion in the literature. For the general surgeon there are several "carcinoid" tumors that he or she must be familiar with because many of these lesions are encountered during emergency laparotomies or incidentally discovered during investigation for vague abdominal pain. This review focuses on the gastrointestinal neuroendocrine tumors that general surgeons are likely to encounter during their career.