Incidence of dysplasia in the anorectal mucosa in patients having restorative proctocolectomy.

The incidence of dysplasia in the mucosal strippings from the anorectal stump was studied in 132 patients treated by restorative proctocolectomy with ileal reservoir for ulcerative colitis and familial adenomatosis. The anorectal mucosa was stripped from the level of division of the gut tube to the dentate line. Of 118 patients with ulcerative colitis, 12 (10.2 per cent) had dysplasia in some part of the large bowel. Mucosal strippings were examined histologically in 118 cases, of which only three (2.5 per cent) showed dysplasia. There was a correlation between dysplasia and the presence of carcinoma and the duration of the disease in the operative specimen of colon and rectum and also in the anorectal mucosal specimen although the number of patients with carcinoma (eight cases) in this analysis was small. All 14 patients with familial adenomatous polyposis showed large bowel mucosal dysplasia in the operative specimen which was severe in six cases. Anorectal mucosal strippings were examined in these patients and 12 showed dysplasia which was severe in three.