The research team led by Levent Erdem from Şişli Etfal Teaching and Research Hospital of Turkey investigated the prevalence and demography of microscopic colitis in patients with diarrhea of unknown etiology and normal colonoscopy in Turkey. This will be published on 21 July 2008, in the World Journal of Gastroenterology addresses this question.
Between March 1998 to July 2005, 129 patients with chronic non-bloody diarrhea of unexplained etiology who had undergone full colonoscopy with no obvious abnormality were included in the study. Two biopsies were obtained from all colonic segments and terminal ileum for diagnosis of microscopic colitis. Lymphocytic colitis was diagnosed in 12 (9%) patientsand collagenous colitis. Biopsy of Turkish patients with the diagnosis of chronic non-bloody diarrhea of unexplained etiology and normal colonoscopic findings will reveal microscopic colitis in approximately 10%. Authors found lymphocytic colitis as 4 times more frequent than collagenous colitis in those patients.
Considering 11.5% of the patients with chronic diarrhea of unknown etiology and normal colonoscopy would have microscopic colitis, biopsy should be taken during colonoscopy in this subset of patients. Although the number of the cases was not enough to answer the question of how many biopsies should be taken and from which part of the colon, the fact that histopathological criteria were determined on all colonic regions in patients with lymphocytic colitis on whom biopsy was performed is promising in terms of diagnostic convenience.
This is an epidemiologic study confirming findings reported from other countries about the frequency of lymphocytic and collagenous colitis and the importance of biopsies for the diagnosis.