抄録
The patient was an 80-year-old man who had been treated with anticoagulant and antiplatelet agents for ischemic heart disease. Upper gastrointestinal endoscopy─performed for progressive anemia─revealed a 10 mm-sized pedunculated reddish polyp at the greater curvature of the middle body of the stomach. The polyp had a granular surface with erosion and a friable section. Considering the risk of hemorrhage from the polyp, the patient underwent polypectomy. Histological examination revealed a well-differentiated tubular adenocarcinoma arising within a hyperplastic polyp. This case suggests that a hyperplastic polyp with erosion or friable regions─even if less than 20 mm in diameter─could potentially undergo malignant transformation.