Gut and Liver, Vol. 5, No. 2, June 2011, pp. 181-186 ORiginal Article Clinical Characteristics of Microscopic Colitis in Korea: Prospective Multicenter Study by KASID Young Sook Park*,∥∥, Dae Hyun Baek*, Won Ho Kim†,∥∥, Joo Sung Kim‡,∥∥, Suk-Kyun Yang§,∥∥, Sung-Ae Jung∥,∥∥, Byung Ik Jang¶,∥∥, Chnag Hwan Choi#,∥∥, Dong Soo Han**,∥∥, Young-Ho Kim††,∥∥, Yong Woo Chung‡‡,∥∥, Sang Woo Kim‡‡,∥∥, and You Sun Kim§§,∥∥ Departments of Internal Medicine, *Eulji University College of Medicine, Yonsei University College of Medicine, Seoul National University College of Medicine, §University of Ulsan College of Medicine, ∥Ehwa Womans University School of Medicine, ¶Yeungnam University College of Medicine, #Chung Ang University College of Medicine, **Hanyang University College of Medicine, Sungkyunkwan University School of Medicine, Hallym University College of Medine, §§Inje University College of Medicine, and ∥∥Korean Association for the Study of the Intestinal Disease (KASID), Korea Background/Aims: Microscopic colitis (MC) encompasses collagenous and lymphocytic colitis and is characterized by chronic diarrhea. In cases of MC, colonic mucosae are macroscopically normal, and diagnostic histopathological features are observed only upon microscopic examination. We designed a prospective multicenter study to determine the clinical features, pathological distribution in the colon and prevalence of MC in Korea. Methods: We prospectively enrolled patients having watery diarrhea no more than 3 times a day between March 2008 and February 2009. We obtained patient histories and performed colonoscopies with random biopsies at each colon segment. Results: A total of 100 patients with chronic diarrhea were enrolled for a nor- mal colonoscopy and stool exam. MC was observed in 22 pa- tients (22%) (M:F 1.2:1; mean age, 47.5 years). Of those 22 patients, 18 had lymphocytic colitis and 4 had collagenous colitis. The entire colon was affected in only 3 cases (13.6%), the ascending colon in 6 cases (27.2%), the transverse colon in 3 cases (13.6%), and the left colon in 3 cases (13.6%). More than 2 segments were affected in 7 cases (31.8%). Nonsteroidal anti-inflammatory drug-associated MCs were observed in 4 cases (18.2%), 3 of which showed improved diarrhea symptoms following discontinuation of the medica- tion. Frequently associated symptoms were abdominal pain and weight loss. Autoimmune diseases were observed in 4 cases (18.2%). Half of the 22 patients with MC improved with conservative care by loperamide or probiotics. Conclu- sions: In a prospective multicenter study of Korean patients with chronic diarrhea, the frequency of MC was found to be approximately 20%, similar to the percentage observed in Western countries. Therefore, the identification of MC is important for the adequate management of Korean patients with chronic diarrhea. (Gut Liver 2011;5:181-186) Key Words: Chronic diarrhea; Microscopic colitis; Collag- enous colitis; Lymphocytic colitis INTRODUCTION The main symptom of microscopic colitis is chronic watery diarrhea. Despite the grossly normal mucosa, it displays typical histologic abnormalities. Microscopic colitis is classified as col- lagenous colitis, in which subepithelial collagen layer thickens around 10 to 100 μm and lymphocytic colitis, characterized by the presence of a lymphocytes more than 20 in 100 epithelial cells.1 In Western countries, it has become apparent that microscop- ic colitis is a common cause of diarrhea, particularly in middle- aged or elderly patients.2 Its etiology and pathophysiology has not been proven yet, but it seems to associate with using of various medication such as lansoprazole and non-steroidal anti inflammatory drugs (NSAIDs).3,4 Also many reports shows microscopic colitis is associated with celiac disease and autoim- mune diseases, such as Type I diabetes and thyroid disease.2 There has been a rapid increase in researches and publica- tions on this disease entity. In Korea, interest about microscopic colitis has been increasing, and some clinical reports by single center are available. Therefore, Korean Association for the Study Correspondence to: Young Sook Park Department of Internal Medicine, Eulji Medical Center, Eulji University College of Medicine, 14 Hangeulbiseok-gil, Nowon-gu, Seoul 139-872, Korea Tel: +82-2-970-8207, Fax: +82-2-970-8621, E-mail: Pys1109@eulji.ac.kr Received on July 23, 2010. Accepted on January 3, 2011. pISSN 1976-2283 eISSN 2005-1212 DOI: 10.5009/gnl.2011.5.2.181 This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.