Microscopic Colitis Is Not So Rare Disease in the Japanese Population

Abstract

Background and study Aim: Microscopic colitis (MC) is recognized as a common cause of chronic diarrhea in the Western countries. However, in Japan, few cases of MC had been reported in the past and frequency of MC has not been clarified yet. The aim of this study is to clarify the frequency of MC in patients with chronic diarrhea in the Japanese population due to take biopsies during colonoscopies if there is no obvious finding of colitis. Methods: A total of 27 (male 11, female 16, mean age 56.4 years old) Japanese patients with chronic diarrhea underwent colonoscopies with biopsies during the period from April 2003 to January 2005. We retrospectively investigated frequency of cause of chronic diarrhea in the basis of pathological findings. Furthermore clinical and endoscopic characteristics of patients with MC were analyzed dividing into collagenous colitis (CC) and lymphocytic colitis (LC). In this study, pathological definitions of CC and LC were thickening of the subepithelial collagen band more than 7 μm and intraepithelial lymphocytosis more than 10 lymphocytes for every 100 epithelial cells, respectively (Am J Gastroenterol 2002:97;794-802). Results: 1. Frequency of cause of chronic diarrhea: CC 29.6% (8/27), LC 14.8% (4/27), Eosinophilic enterocolitis 3.7% (1/27), Infectious colitis 3.7% (1/37), Ischemic colitis 3.7% (1/37), Normal 44.5% (12/37), 2. Clinical and endoscopic characteristics of CC (n = 8) and LC (n = 4): a) Mean age: CC 66.3 yrs. LC 45.8 yrs. b) Gender (male:female): CC 1:1, LC 1:3, c) Frequency of diarrhea per day (mean): CC 5.9 ± 2.9, LC 7.8 ± 2.6, d) Mean duration of diarrhea (months): CC 2.0 ± 2.0, LC 3.3 ± 1.5, e) Past illness: CC; chronic renal failure 3, collagen disease 3, diabetes 1, LC; diabetes 1, f) Drug history: CC; lansoprazole 6, loxoprofen sodium 4, LC; none, g) Endoscopic feature: i) slight thickening of colonic mucosa; CC 75% (6/8), LC 75% (3/4), ii) proliferation of capillary vessels; CC 37.5% (3/8), LC 0% (0/4), iii) contact bleeding; CC 12.5% (1/8), LC 50% (2/4). Conclusions: MC (CC and LC) was major cause of chronic diarrhea in the Japanese population in our investigation. We could observe endoscopically slight mucosal abnormalities in most of CC and LC patients.