Practical Approach to Microscopic Colitis and Inflammatory Bowel Disease

19 INTRODUCTION Inflammatory disorders of the intestines can be divided into those with macroscopic mucosal changes (the traditional inflammatory bowel diseases: ulcerative colitis and Crohn’s disease) and those with primarily microscopic changes. Microscopic colitis is a chronic diarrheal condition that is separated into two main subtypes: collagenous colitis and lymphocytic colitis. These two conditions have similar clinical and histologic features, but are distinguished by the presence or absence of a thickened subepithelial collagen band. Inflammatory bowel disease (IBD) is traditionally separated into two distinct clinical entities: Crohn’s disease and ulcerative colitis. Although there is considerable symptom overlap between these diseases, there are several features that help distinguish them. The aim of this review is to provide a concise comparison of the epidemiology, clinical features and natural history, pathophysiology and risk factors, and management of microscopic colitis compared to IBD.