[Proctitis of diversion on an excluded rectum in patients with hemorrhagic rectocolitis]

Diversion colitis is characterized by inflammatory lesions affecting colon or rectum excluded from the fecal stream for varied etiologies. These lesions may mimic both ulcerative colitis and Crohn's disease. The aim of our study was to examine the excluded rectum in patients with ulcerative colitis, and to study the evolution of the pathological lesions after ileo-rectal anastomosis.

Eighteen patients with ulcerative colitis treated by total colectomy before ileo-rectal anastomosis were studied. The pathological features i.e. glandular alteration, inflammatory infiltrate and mucosal ulceration or fissure, were studied during 3 periods: initial colectomy, excluded rectum at surgery for anastomosis and rectal biopsies after anastomosis.

We observed on the excluded rectum a follicular lymphoid hyperplasia (18 cases), granulomas with giant cells (9 cases), mucosal fissures (9 cases). The inflammation extended to the submucosa in all cases and was occasionaly transmural. These lesions disappeared after the anastomosis and then seemed to be connected with the rectal diversion.

The pathological changes of diversion proctitis that includes mucosal fissures, granulomas with giants cells or transmural inflammation, may lead to an erroneous diagnosis of Crohn's disease. The review of the previous colectomy is then mandatory to confirm the initial diagnosis of ulcerative colitis. These lesions disappear after anastomosis.