Mixed neuroendocrine–non‐neuroendocrine neoplasm associated with autoimmune gastritis

A 60‐year‐old woman presented with a protruding tumor at the anterior wall of the middle gastric body, and she was positive for anti‐parietal cells antibodies with elevated serum gastrin level. Final diagnosis was a mixed neuroendocrine–non‐neuroendocrine neoplasm consisting of adenocarcinoma (tub1) and neuroendocrine tumor G2 with autoimmune gastritis. Gastric mixed neuroendocrine–non‐neuroendocrine neoplasms (MiNENs) composed of neuroendocrine tumor (NET) and adenocarcinoma is extremely rare in the autoimmune gastritis background. Molecular analysis of each component of the NET and adenocarcinoma will define the pathogenesis of this rare gastric MiNEN.