Well-differentiated Neuroendocrine Tumor (Carcinoid) in Chronic Atrophic Gastritis

Type 1 neuroendocrine tumors in the stomach arise in the setting of chronic atrophic gastritis (autoimmune gastritis). Parietal cell loss leads to hypochlorhydria, which stimulates G cells to release excess gastrin causing hypergastrinemia. This hormone acts on ECL (enterochromaffin-like) neuroendocrine cells, causing hyperplasia and sometimes tumor formation. These lesions tend to be indolent and have a 5-yr survival rate of almost 95%. Metastases are rare.