Ulcerative Colitis : Gross Pathology
The gross appearance of ulcerative colitis (UC) depends upon the stage of the disease. In the initial stages, the mucosa is markedly hyperemic and granular and covered with mucus and petechial hemorrhages. With disease progression, the mucosa becomes friable with appearance of punctate ulcers followed by irregular broad-based ulcers of various sizes. Ulceration may undermine the mucosa creating mucosal bridges. The ulcers are aligned along the long axis of the colon; however, longitudinal ulcers connected by transverse ulcers, a feature characteristic of Crohn disease, are not present in UC. There is abrupt transition between affected areas and adjacent uninvolved mucosa (see images 1,2, & 3). The disease and the accompanying mucosal changes are usually more severe in distal colon. Against a backdrop of mucosal ulceration, islands of residual (non-ulcerated) and regenerating mucosa bulge into the lumen creating pseudopolyps. The pseudopolyps are usually small and multiple (as seen in this image). On occasion, they may be quite large and raise the concern for malignancy.