title: Microscopic colitis: clinical findings, topography and persistence of histopathological subgroups.
abstract: BACKGROUND
  Uncertainty remains on topography and persistence of histological subgroups of microscopic colitis (MC).
  
  
  OBJECTIVE
  To assess longitudinal clinical, endoscopic, histological, and therapeutic description of MC subgroups including patients with incomplete findings of MC (MCi).
  
  
  METHODS
  Retrospective review of a consecutive cohort with MC and histological reassessment of MCi.
  
  
  RESULTS
  Clinical characteristics of 168 patients with lymphocytic colitis (LC), 270 with collagenous colitis (CC) and 101 with MCi were similar. At colonoscopy 95% (95% CI: 91-98%) of CC and 98% (93-100%) of LC cases had diagnostic histopathology of MC in both left and right colon. Eight and three patients had characteristics of MC only in the left and right colon, respectively. Histology findings resembling coexistence of the other MC subtype was present in 48% (40-55%) with CC and 24% (18-31%) with LC. A first diagnosis of MC was made in 49 (30%) of 164 patients only at repeat endoscopy. Another 34 of 115 (30%) with MC in the first endoscopy did not fulfil the MC criteria at repeat endoscopy. Only seven cases had a primary endoscopy without histopathological abnormalities. Fifteen percentage of MCi were reclassified as MC. Ileal inflammation was present in 33 of 81 patients. Budesonide was efficacious in all MC subgroups irrespective of bile acid malabsorption.
  
  
  CONCLUSIONS
  Clinical characteristics of microscopic colitis subgroups are indistinguishable. Biopsies from the left colon suffice to exclude microscopic colitis, and the histological diagnosis of microscopic colitis is inconsistent over time. Ileal inflammation is common. The term microscopic colitis should perhaps be considered one clinical entity and include lymphocytic colitis, collagenous colitis, and incomplete findings of microscopic colitis.
authors.affiliation: Section of Gastroenterology, Department of Medicine, Køge Hospital, Køge, Denmark.
authors.forename: C
authors.initials: C
authors.lastname: Bjørnbak
authors.forename: P J H
authors.initials: PJ
authors.lastname: Engel
authors.forename: P L
authors.initials: PL
authors.lastname: Nielsen
authors.forename: L K
authors.initials: LK
authors.lastname: Munck
mesh_terms: D000368:Aged; D001706:Biopsy; D015331:Cohort Studies; D046728:Colitis, Microscopic / Q000175:diagnosis*; D003113:Colonoscopy / Q000379:methods; D003937:Diagnosis, Differential; D003967:Diarrhea / Q000473:pathology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies