Figure 6

(a–d) Disorders that mimic IBD, or cause changes in the pattern and severity of inflammation in patients with known IBD. (a) Patient with known UC who developed C. difficile-associated pseudomembranous colitis and CMV infection, which caused the patient to become refractory to medical treatment. Classic C. difficile-associated pseudomembranes are seen in this image, which are occurring on a background of mucosa that is consistent with UC. (b) High-power magnification of one portion of the mucosa shows multiple CMV inclusions within stromal cells. (c) Ipilimumab-associated diffuse pancolitis with features similar to IBD. In this photograph, the mucosa shows diffuse ulceration and superficial fissuring ulceration. An associated inflammatory polyp is noted in the right side of the field. (d) Elderly patient with severe atherosclerotic disease developed segmental areas of severe chronic active colitis with ulceration, features that mimic IBD. In other areas of the resected colon, there are arterial thrombi involving small and medium-sized blood vessels in various stages of organization. This patient had no history of IBD before development of chronic recurrent ischemic colitis.