[A case of anorectal malignant melanoma appearing 1 year after endoscopic mucosal resection of a rectal adenocarcinoma].

We present a case of a 61-year-old woman who underwent endoscopic mucosal resection (EMR) for early-stage colorectal cancer. However, because the condition of the horizontal margin of the resected tumor was unknown, she further underwent local transanal excision. Lower gastrointestinal endoscopy performed 1 year later showed protruding lesions both on the scar tissue and in the vicinity.