Review
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World J Gastroenterol. Nov 21, 2012; 18(43): 6206-6215
Published online Nov 21, 2012. doi: 10.3748/wjg.v18.i43.6206
Microscopic colitis
Gianluca Ianiro, Giovanni Cammarota, Luca Valerio, Brigida Eleonora Annicchiarico, Alessandro Milani, Massimo Siciliano, Antonio Gasbarrini
Gianluca Ianiro, Giovanni Cammarota, Brigida Eleonora Annicchiarico, Alessandro Milani, Massimo Siciliano, Antonio Gasbarrini, Gastroenterology Unit, A. Gemelli University Hospital, Catholic University of Sacred Heart, 00168 Rome, Italy
Luca Valerio, Institute of Public Health, A. Gemelli University Hospital, Catholic University of Sacred Heart, 00168 Rome, Italy
Author contributions: Ianiro G and Cammarota G contributed to the conceptual design of the manuscript; Ianiro G and Valerio L contributed to the draft of the article; Ianiro G, Valerio L, Annicchiarico BE and Siciliano M reviewed and summarized the literature; Cammarota G, Milani A and Gasbarrini A revised critically the article; Gasbarrini A approved the final submitted manuscript.
Correspondence to: Antonio Gasbarrini, Professor, MD, Gastroenterology Unit, A. Gemelli University Hospital, Catholic University of Sacred Heart, 00168 Rome, Italy. agasbarrini@rm.unicatt.it
Telephone: +39-6-30156018 Fax: +39-6-30157249
Received: April 17, 2012
Revised: May 23, 2012
Accepted: June 28, 2012
Published online: November 21, 2012
Abstract

Microscopic colitis may be defined as a clinical syndrome, of unknown etiology, consisting of chronic watery diarrhea, with no alterations in the large bowel at the endoscopic and radiologic evaluation. Therefore, a definitive diagnosis is only possible by histological analysis. The epidemiological impact of this disease has become increasingly clear in the last years, with most data coming from Western countries. Microscopic colitis includes two histological subtypes [collagenous colitis (CC) and lymphocytic colitis (LC)] with no differences in clinical presentation and management. Collagenous colitis is characterized by a thickening of the subepithelial collagen layer that is absent in LC. The main feature of LC is an increase of the density of intra-epithelial lymphocytes in the surface epithelium. A number of pathogenetic theories have been proposed over the years, involving the role of luminal agents, autoimmunity, eosinophils, genetics (human leukocyte antigen), biliary acids, infections, alterations of pericryptal fibroblasts, and drug intake; drugs like ticlopidine, carbamazepine or ranitidine are especially associated with the development of LC, while CC is more frequently linked to cimetidine, non-steroidal antiinflammatory drugs and lansoprazole. Microscopic colitis typically presents as chronic or intermittent watery diarrhea, that may be accompanied by symptoms such as abdominal pain, weight loss and incontinence. Recent evidence has added new pharmacological options for the treatment of microscopic colitis: the role of steroidal therapy, especially oral budesonide, has gained relevance, as well as immunosuppressive agents such as azathioprine and 6-mercaptopurine. The use of anti-tumor necrosis factor-α agents, infliximab and adalimumab, constitutes a new, interesting tool for the treatment of microscopic colitis, but larger, adequately designed studies are needed to confirm existing data.

Keywords: Microscopic colitis; Lymphocytic colitis; Collagenous colitis; Watery diarrhea; Immunosuppressive agents; Anti-tumor necrosis factor-α agents