the standard criteria of IBS (ROMEIII), the Western study reports the 28% match and claims that colonoscopy with histology confirm is important in patients suspicious irritable bowel syn- drome.23 The distribution of microscopic colitis is not even. In some case of collagenous colitis, thickening of subepithelial collagen layer distributes on ascending and transverse colon, it does not appear in the sigmoid colon and rectum.24 Also in lymphocytic colitis, some of lesion spread in ascending and transverse colon, therefore sigmoidoscopy is not enough to diagnose the micro- scopic colitis. Nine cases out of 22 cases (40.9%) of microscopic colitis in this study are diagnosed in ascending and transverse colon. A group of patients with suspicious lymphocytic colitis and suspicious collagenous colitis in this study, who show increase in intraepithelial lymphocytes or thickening of collagen layer which doesn’t fit the definition, is still to be concerned about whether the condition will progress or not. There is no report on this, but it should be followed up with concern. As far as the treatment of microscopic colitis is concerned, patients should avoid caffeine and alcohol which worsen the symptom. The drug therapy should be accompanied with the diet modification. The principle of treatment is step up therapy. When symptom is mild, loperamide and cholestyramine can be administrated, if there is no reaction to these drugs, budesonide, and aminosalicilates can be used. Also, when resistance to ste- roid occurs, immunosuppressive drugs, such as azathioprine and methotraxate, can be administrated. It has been suggested that budesonide, 9 mg/day for 6 to 8 weeks, is the most effective.25 However, the limitation of budesonide is that when treatment is stopped, the symptom is recurrent. Therefore there is further research to find the right period of treatment.1 The symptoms were controlled by stopping causing drugs, and budesonide and mesalazine were added for one case and the treatment result is being observed. Long term prognosis of microscopic colitis is favorable in general. One study reported that in the case of collagenous coli- tis, 63% was resolved for 3.5 years and only 29% of the case needed continuing drug therapy.15 In the case of lymphocytic colitis, more than 80% cases show improvement in clinical symptoms and histology for 38 months. There are reports of malignancy in the cases of collagenous colitis with breast can- cer (2.34%), lung cancer (1.75%), and colorectal cancer (2.82%). In the case of lymphocytic colitis, there were patients with breast cancer (5.31%), lung cancer (1.06%), and prostate cancer (1.86%).2 However, there were no statistically significant rela- tion yet between microscopic colitis and malignancy including colorectal cancer. Therefore, it will be necessary to keep moni- toring the 22 patients diagnosed with microscopic colitis in this study. There has been an increase of the patients with chronic diar- rhea diagnosed as microscopic colitis. This study tries to know Park YS, et al: Microscopic Colitis in Korea 185 the frequency, clinical characteristics, causing factor and treat- ment result of microscopic colitis in Korea through multicenter prospective study. Although the frequency might have been higher than the actual case since the enrolled patient were treat- ed in teaching hospital or institutional hospital, it suggests that the frequency of microscopic colitis in Korea is about the same level in Western countries. 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