Different types of mucosal adaptation in the ileal reservoir after restorative proctocolectomy. A two-year follow-up study

A histomorphologic study of the pelvic pouch mucosa during the first two years of function was performed in 11 consecutive patients treated for ulcerative colitis. Two types of mucosal adaptation were delineated. Type A response (5 patients) showed stable slight atrophy, normal numbers of goblet cells, and numerous sulphated mucin positive cells. The frequency of mitoses was higher than in the normal ileum. The degree of acute and chronic inflammation was low and decreasing or stable. Dysplasia was never seen. Type B response (5 patients) comprised progressive, finally severe atrophy accompanied by increasing degree of acute inflammation. The number of mitoses was higher than in type A response. In two patients the number of goblet cells was moderately/severely decreased and epithelial atypia or low grade dysplasia occurred repeatedly. The response was regarded as indeterminate in one patient. The determination of the types of mucosal adaptation may help in the planning of the follow-up of these patients.