Gastric Neuroendocrine Tumors (NETs), formerly known as Gastric Carcinoids (GCs), are neoplasms derived from enterochromaffin cells of
the stomach. This heterogeneous group of tumors has been historically divided into three types, best distinguished by etiology. Type I gastric
carcinoids, comprising 70-80% of gastric neuroendocrine tumors, are associated with autoimmune chronic atrophic gastritis. As a result of this
condition, widespread parietal cell loss leads to chronic achlorhydria, causing G cell hypersecretion of gastrin. Type II gastric carcinoids,
accounting for 5-8% of gastric are associated with gastrinomas and Zollinger-Ellison Syndrome. Neoplastic G cells secrete gastrin, again
resulting in hypergastrinemia. In both Types I and II gastric carcinoids,exorbitant levels of gastrin lead to hyperplasia, dysplasia and ultimately
neoplastic changes in the stomach. Type III gastric carcinoids,constituting 15-25% of gastric NETs, are sporadic in nature, without
associated increases in gastrin levels. The pathophysiology of Type III gastric carcinoids remains to be elucidated.
Last date updated on September, 2024