Colorectal carcinoma in patients with ulcerative colitis and recent colonoscopy.

Longstanding ulcerative colitis, particularly pancolitis, is associated with an increased risk of colorectal neoplasia. For this reason surveillance colonoscopy at regular intervals has been recommended to identify early cancers or high grade dysplasia. Three cases are described of patients with ulcerative colitis of greater than 10 years duration who presented with colorectal carcinoma within three years of colonoscopy.