Low prevalence of ‘classical’ microscopic colitis but evidence of microscopic inflammation in Asian Irritable Bowel Syndrome patients with diarrhoea

Ida Hilmi,Sanjiv Mahadeva,Jayalakshmi Pailoor,Khean-Lee Goh,Juanda Leo Hartono

doi:10.1186/1471-230x-13-80

Abstract

BackgroundThere is increasing evidence for the role of microscopic inflammation in patients with IBS. We aimed to examine the prevalence of microscopic colitis and inflammation in Malaysian IBS patients with diarrhoea (IBS-D).MethodsConsecutive patients who met the Rome III criteria for IBS-D and asymptomatic controls were prospectively recruited. Colonoscopy was performed in all study subjects and systematic biopsies taken from all segments of the colon. The diagnosis of lymphocytic colitis and collagenous colitis was made using previously defined criteria. Patients with post infectious IBS were excluded.Results120 subjects (74 IBS-D, 46 controls) were recruited during the study period. In the IBS-D group, the colonoscopic (macroscopic) findings were as follows; normal findings n = 58 (78.4%), diverticula disease n = 5 (6.8%), diminutive polyps n = 9 (12.2%) and haemorrhoids n = 2(2.7%). No subject under the age of 40 had any significant findings. Microscopically, there was only one case (1.3%) with histology consistent with collagenous colitis. However, the IBS-D patients had a higher prevalence of moderate microscopic inflammation (n = 11, 14.9%) compared to controls (n = 1, 2.2%) (p = 0.005).Conclusions‘Classical’ microscopic colitis is uncommon in Malaysian patients with IBS-D but a significant number of adults showed evidence of microscopic inflammation.

Highlights

There is increasing evidence for the role of microscopic inflammation in patients with Irritable Bowel Syndrome (IBS)
A subset of IBS patients, in particular those with diarrhoea (IBS-D) who do not undergo colonoscopy and biopsies would have missed a diagnosis of microscopic colitis
The primary objective was to look at the prevalence of microscopic colitis in patients who were diagnosed with IBS patients with diarrhoea (IBS-D) as defined by the Rome III criteria

Summary

Introduction

There is increasing evidence for the role of microscopic inflammation in patients with IBS. Irritable Bowel Syndrome (IBS) is defined as a chronic abdominal discomfort associated with altered bowel habit It is a common gastrointestinal disorder worldwide, with prevalence rates ranging from 2-22% in the West (depending on criteria used) [1] and a rate of 15% in the Malaysian population, based on the Rome II criteria [2,3]. The exact pathogenesis of IBS is generally unknown but postulated mechanisms include alterations in gut motility, visceral hypersensitivity, bacterial flora, together with ‘Classical’ microscopic colitis is a histopathological diagnosis which is currently accepted as an umbrella term for either lymphocytic colitis or collagenous colitis Both subtypes share similar histological features, apart from the fact that collagenous colitis has a significantly thickened sub-epithelial collagen layer. A diagnosis of microscopic colitis should prompt a search for associated autoimmune conditions such as coeliac disease

Objectives

Methods

Results

Conclusion