Microscopic colitis in patients with ulcerative colitis or Crohn’s disease: a retrospective observational study and review of the literature

AbstractObjectives: Onset of microscopic colitis (MC) in patients with ulcerative colitis (UC) or Crohn’s disease (CD), or vice versa, has been reported occasionally but the subject is not well described. We therefore report a retrospective observational study of such patients and review the literature.Methods: Forty-six Swedish gastroenterology clinics were contacted about patients with diagnoses of both inflammatory bowel disease (IBD) and MC. Publications were searched on PubMed.Results: We identified 31 patients with onset of MC after a median (range) of 20 (2–52) years after diagnosis of IBD, or vice versa; 21 UC patients developed collagenous colitis (CC) (n = 16) or lymphocytic colitis (LC) (n = 5); nine CD patients developed CC (n = 5) or LC (n = 4); one CC patient developed CD. Of the 21 UC patients, 18 had extensive disease, whereas no consistent phenotype occurred in CD. Literature review revealed 27 comprehensive case reports of patients with diagnoses of both IBD and MC. Thirteen MC patients ...