摘要We report a unique case of intramucosal carcinoma in a tubulovillous adenoma arising from a single diverticulum. Endoscopic mucosal resection (EMR) was carried out successfully and completely with the assistance of laparoscopy. A 71-year-old man was admitted to our hospital because of melena and anemia. Emergent colonoscopy showed diverticulosis in the right-sided colon. However, endoscopy could not exactly detect the bleeding site. A flat elevated polyp was found within a single diverticulum located in the descending colon and diagnosed as an intramucosal carcinoma, as magnifying chromoendoscopy revealed a type Ⅳ pit pattern. As his diverticular bleeding repeated, a rightsided hemicolectomy was decided for treatment, the polyp within the diverticulum was also completely removed by EMR with the assistance of laparoscopy. Although a colonic perforation was detected immediately after EMR, the perforation was closed with endoclips intraluminally and also repaired laparoscopically from the serosal side. Histologically, the resected lesion was an intramucosal well-differentiated adenocarcinoma and the surgical margin was free of tumor.