Microscopic colitis: prevalence and distribution throughout the colon in patients with chronic diarrhoea.

BACKGROUND Microscopic colitis presents with chronic diarrhoea with or without abdominal pain. Microscopic colitis is an important cause of chronic diarrhoea. It can be distributed throughout the colon, as well as limited to the right colon. Microscopic colitis is associated with coeliac disease. We studied the prevalence and distribution of microscopic colitis in patients with diarrhoea and normal colonoscopy and we studied the association with coeliac disease. METHODS Colonoscopy was performed. Biopsies were taken from every segment of the colon. Lymphocytic colitis was defined as the presence of more than 20 lymphocytes per 100 epithelial cells and collagenous colitis was defined as thickening of the basal membrane of more than 10 microm. Upper endoscopy was performed if upper intestinal symptoms were present. If this was the case, small bowel biopsies were taken. RESULTS Microscopic colitis was found in 13 out of 103 patients. The distribution was diffuse throughout the colon in ten and restricted to the right colon in three patients. In seven patients, upper endoscopy was performed. Marsh I/II lesions were found in six out of seven patients. CONCLUSION Microscopic colitis was limited to the right colon in 23% of patients. Biopsies of macroscopically normal colonic mucosa in patients with diarrhoea is mandatory.