An 80-year-old man with a chief complaint of anemia underwent upper gastrointestinal endoscopy, and a 25-mm, white-toned, and elevated lesion was found on the posterior wall of the lower gastric body. Histopathological analysis revealed that the lesion was a mixed neuroendocrine-non-neuroendocrine neoplasm (MiNEN) comprising adenocarcinoma and neuroendocrine tumor. This patient had an intramucosal carcinoma with a G1-equivalent neuroendocrine neoplasm (NEN) component, and no apparent recurrence 6 months after endoscopic submucosal dissection (ESD) resection. MiNEN is a relatively new concept, which was modified in the 2019 World Health Organization (WHO) classification, and there is currently a lack of an established treatment and evidence for this disease. Reports of endoscopic resection of early gastric MiNEN are rare. We here report a case of successful endoscopic resection in a patient with MiNEN, together with a literature review.
