[Prevalence of microscopic colitis in a group of patients from Montevideo, Uruguay].

INTRODUCTION The microscopic colitis (MC) is characterized by the presence of aqueous chronic diarrhea (ACD) with inflammatory elements in the colon only detectable by microscopy. OBJECTIVES To know the prevalence of MC in the group of patients with ACD attending the Endoscopy Service of the British Hospital from Montevideo. MATERIAL AND METHODS We retrospectively included patients with ACD who were studied by endoscopy during a period of 5 years and the endoscopy was normal or showed minimal alterations. Biopsies in different parts of the colon were taken to this group of patients aiming to diagnose this entity. RESULTS We included 180 patients, 101 women (56%) and 79 men (44%). No lesion was found in the endoscopy in 67% of them, 27% had a diverticular colopathy and 5% a non-specific colitis. Out of the total number of patients, 9% had a histological study compatible with MC, 82% had lymphocytic colitis (CL) and 18% collagenous colitis (CC), with a ratio between men and women of 1.8:1 and 1:2, respectively. The mean age for the diagnosis was 43 years old in the group of CL and 61 years old in the group of CC. Endoscopic lesions were not found in 94% of patients with MC and only 1 patient presented a non-specific colitis at the endoscopy. The 65% of the remaining patients did not show histological alterations and 26% of them presented non-specific inflammatory changes. CONCLUSIONS The prevalence of MC in our series was similar to that found in other publications and alterations in the colonic mucosa were not found in most cases. The CL was the most frequent form of presentation and was found at an earlier age than the CC. The CL was more frequent in men. Knowing that the CM is a rare illness in our environment, these findings suggest the importance of taking multiple biopsies from different parts of the colon when patients with ACD are studied.