RESUMEN
BACKGROUND: Gastric mixed adenoma-neuroendocrine tumors (NETs) are quite rare. In the 2019 world health organization classification of tumors of the digestive system, these were designated as a combination of grade 1 or grade 2 NETs and adenomas or tubular adenomas. There are no treatment guidelines for these tumors, and pathological and clinical studies are ongoing. Herein, we review previous case reports and present a case of gastric mixed adenoma-NET. CASE SUMMARY: A 66-year-old man underwent gastrointestinal endoscopy for the evaluation of upper abdominal pain. Histopathological examination of the biopsy specimen indicated the possibility of gastric cancer. A histopathological examination by endoscopic submucosal dissection showed a mixed adenoma-NET that was completely excised by endoscopic submucosal dissection. No recurrence was observed on gastrointestinal endoscopy at the 6-mo follow-up. CONCLUSION: Clinicians' awareness of this rare tumor is important for its timely diagnosis and treatment.