[A case of colonic mucosa-associated lymphoid tissue lymphoma observed under endoscopy with narrow-band imaging].

A 79-year-old man presented with constipation and anal bleeding. Colonoscopy revealed a reddish submucosal tumor of the transverse colon that was 20mm in diameter. Magnified endoscopy with narrow-band imaging (NBI) of the tumor surface revealed a type I pit pattern with decreased density and dilated tree-like microvessels. Furthermore, endoscopic ultrasonography showed that the tumor was limited to the submucosa. A biopsy was subsequently performed, which suggested mucosa-associated lymphoid tissue (MALT) lymphoma. This diagnosis was confirmed by endoscopic submucosal dissection (ESD). To the best of our knowledge, this is the first case report in which magnified endoscopy with NBI was successfully used to diagnose a MALT lymphoma of the colon. In addition, this case report demonstrates the utility of ESD for the therapeutic diagnosis of relatively large lesions with evidence of invasion limited to the submucosa.