Chronic Colitis in Biopsy Samples: Is It Inflammatory Bowel Disease or Something Else?

Chronic colitis, regardless of type, is defined histologically by chronic inflammation, mainly plasmacytosis, in the lamina propria. Specific diagnosis of chronic colitides in biopsies can be challenging for practicing pathologists. This article focuses on discussing specific histologic features in biopsies of the inflammatory bowel diseases (IBDs), including ulcerative colitis, Crohn colitis, and colitis of indeterminate type. It also offers suggestions as to how to separate the IBDs from other chronic colitides, such as lymphocytic colitis, collagenous colitis, diverticular disease-associated colitis, diversion colitis, and chronic colitides that are due to drugs. Normal histology in colon biopsies is also briefly discussed.