Diversion colitis: a clinicopathologic study of 21 cases.

Inflammation occurring in a defunctionalized portion of bowel, following either ileostomy or colostomy, has long been recognized by endoscopists. However, little has been written about this entity, particularly the histopathologic changes. Glotzer et al in 1981 described 10 cases, and coined the term "diversion colitis". We studied 21 patients without previous history of inflammatory bowel disease who, for reasons including perforated diverticulitis, carcinoma, or trauma, had loop colostomies or Hartmann's procedure performed. Many of these patients became symptomatic with complaints related to the defunctionalized bowel, including rectal discomfort, pain, discharge, and bleeding. Nineteen patients had endoscopic examinations, which revealed a variety of findings including mucous plugs, friability, petechia, erythema, ulcers, exudate, and nodules or polyps. All except one case had tissue from the excluded portions of bowel available for pathologic examination. Most displayed nonspecific changes with mild-to-moderate lymphoplasmacytic infiltrates in the lamina propria, mild architectural alterations of the crypts, and slight decrease in crypt numbers. Ulceration, cryptitis, and crypt abscesses simulating ulcerative colitis were uncommon findings and were observed almost exclusively in more severe cases. Granulomas were observed in two cases, raising the possibility of Crohn's disease.