The colitis may extend throughout the colon or involve only part of it. Chracteristically the rectal mucosa is affected. Granularity is commonly seen as are superficial or deep ulcerations which may by linear, serpiginous, or ovoid. This slide shows the appearance of longstanding ulcerative colitis with tubularization of the colon. Plaques of exudate and punctiform petechial hemorrhages are also apparent.
Ulceration is a dominant abnormality in Crohn's disease.
This slide shows multiple larger, deep, excavated ulcers with distinct margins in a patient with Crohn's disease. This slide shows diverticulosis of the colon. Although the sigmoid is the most common site, these outpouchings may occur throughout the colon and are seen as 2 to 5 mm openings. Obstruction of these openings may result in diverticulitis while ulceration at the dome of a diverticulum may erode into a vessel and result in diverticular bleeding. A larger angiodysplasia and multiple small angiodysplasias are interconnected in these views.