A practical approach to colitis

Etiologies for colonic inflammation and injury are numerous and may be the result of idiopathic, infectious, iatrogenic, and autoimmune processes. Colitides most likely to be encountered in clinical practice are those caused by idiopathic inflammatory bowel disease, ischaemia, radiation, diverticulosis, and medications. Additionally, collagenous and lymphocytic colitis are entities to be considered in the setting of a normal endoscopic exam. Although evaluation of specimens for inflammatory colon disorders can be challenging, the differential diagnosis can be narrowed if the histologic features are interpreted in the context of the endoscopic and clinical findings. This article aims to provide the reader with a review of the most commonly encountered inflammatory processes of the colon and to offer guidance to differentiate between entities bearing in mind that there is significant overlap between many of these disorders.