Ulceration with granulation tissue is a prominent feature in acute stages of ulcerative colitis. Residual inflamed and hyperemic mucosa appears polypoid (pseudopolyps). This image shows an ulcer in the center surrounded by pseudopolyps with mucosal bridging. The appearance of submucosa depends upon the stage of the disease and may be normal, inflamed, fibrotic, hyperemic, or infiltrated by excessive fat. The submucosal vessels may show endarteritis obliterans with or without thrombosis in a small percentage of cases.