P016 Microscopic Colitis With Quiescent Crohn’s Disease: A Case Report

Abstract

CASE: Microscopic Colitis (MC) coexistent in patients with inflammatory bowel disease (IBD) is rare. It is not clear if this is merely a chance association or results from a common genetic predisposition or pathophysiological pathway. It has also been hypothesized that MC is a part of spectrum of IBD. We report a case of Crohn’s disease whose clinical course was complicated by collagenous colitis while on adalimumab. This is a case of a 62-year-old veteran with past medical history of tobacco dependence, GERD and Crohn's disease. Crohn’s colitis was diagnosed in 2000 and patient was treated with adalimumab with mucosal healing and histological remission. She was diagnosed with microscopic colitis in August 2017 that was treated with budesonide. Each time the budesonide was titrated off, her microscopic colitis would flare and during one of the titrations, she required hospitalization. Colonoscopy during this time showed no endoscopic evidence of active colitis. The mucosa appeared normal and biopsies throughout the colon revealed quiescent disease. Biopsies, however, did show irregularly thickened collagen table entrapping small capillaries and inflammatory cells consistent with collagenous colitis. There was no evidence of acute inflammation, granuloma, dysplasia or malignancy. She was placed back on budesonide 9 mg daily which resolved her symptoms of diarrhea. Microscopic Colitis (MC) and inflammatory bowel disease (IBD) differ in their epidemiology, clinical symptoms, endoscopic findings and histopathology. Colonic mucosa appears normal on endoscopy and crypt architecture is not distorted typically in microscopic colitis. A retrospective observational study of 31 patients with both IBD and MC showed a common feature of having long standing Ulcerative Colitis (UC) at a younger age with onset of CC (collagenous colitis) at an older age. Findings of specific negative associations with Crohn’s disease were detected for a number of taxa within the family of ruminococcaceae, in a study of microbiome in new onset Crohn’s disease. Several species of this family are important for the maintenance of gut homeostasis. A recent study on gut microbiota in collagenous colitis demonstrated that the patients with CC displayed a shift in some taxa, like the ruminococcaceae family, which resembles the above-described IBD associated dysbiosis. This could indicate that the pathogenesis of the diseases might have mechanisms related to the gut microbiome in common. The association between collagenous colitis and IBD is still unclear. In patients with Ulcerative Colitis or Crohn’s disease, the onset of new symptoms of non-bloody diarrhea with no signs of IBD relapse on endoscopy, mucosal biopsies should be obtained to rule out MC.