MURAL BRIDGING LESIONS IN COLONIC CROHNS-DISEASE

A case of Crohn's colitis with mural bridging lesions is described. Th e bridging lesions comprised colonic-type mucosa, smooth muscle, nerve fibers, with foci of adipose tissue and fibrous connective tissue. Th e lesions arose from the muscularis propria proximal to colonic strict ures and possibly due to diverticular outpouching of the colonic wall associated with increased intraluminal pressure, although the exact me chanism of their formation appears unclear. This entity has not been p reviously described in inflammatory bowel disease, to our knowledge. B ridging pseudopolyps are seen in ulcerative colitis and rarely in Croh n's disease but do not contain substantial amounts of smooth muscle an d/or nerve fibers. We believe that the mural bridges described in this article represent residual muscularis propria at the site of divertic ular formation due to long-standing Crohn's colitis. We speculate that the stricture formation seen distal to the site of the mural bridging lesions may have been an important factor in formation of the colonic diverticula and, hence, these lesions that we interpret as representi ng residual muscularis propria adjacent to sites of diverticular forma tion in long-standing Crohn's colitis.