Non-IBD colitides: clinically useful histopathological clues

Apart from inflammatory bowel diseases (IBD), there are several other form of colitis that may resemble macroscopically IBD, entering the differential diagnosis. These forms are represented by infectious colitis, ischemic colitis, pseudomembranous colitis, colitis related to diverticular disease, colitis related to mucosal prolapse, drug colitis, allergic colitis, and microscopic colitis. However, to distinguish between these forms is not always easy, and it frequently requires a strict interrelationship between the pathologist and the gastroenterologist. Here we discuss the more frequent forms of non- inflammatory bowel diseases colitides, trying to give useful hints for helping the clinician to better understand the extent to which the pathologist is called to give a definitive response in the differential diagnosis of these entities.