title: Microscopic colitis and colorectal neoplastic lesion rate in chronic nonbloody diarrhea: a prospective, multicenter study.
abstract: BACKGROUND
  Lymphocytic and collagenous colitis are emerging as common findings in subjects undergoing colonoscopy for chronic non-bloody diarrhea (CNBD). Data concerning microscopic colitis (MC) are still limited and affected by controversial epidemiological evidences. Recent converging lines of evidence suggest that MC correlates a lower risk of colorectal neoplasia. Accordingly, we prospectively assessed MC prevalence in a multicenter cohort of subjects submitted to colonoscopy for CNBD, thereby defining whether MC influences the risk of colorectal neoplasia.
  
  
  METHODS
  Consecutive patients with CNBD of unknown origin underwent pan-colonoscopy with multiple biopsies. The prevalence of neoplastic patients in MC was compared with that observed in negative CNBD subjects.
  
  
  RESULTS
  Among 8006 colonoscopy, 305 subjects were enrolled for CNBD. Patients with CNBD were more likely to be women than men (odds ratio = 1.5; P = 0.001). Histopathology detected high prevalence of MC (16%) with a clear predominance of collagenous colitis (70%). A striking age-dependent rise in MC-associated risk was observed, depicting outstanding differences among varying age groups, as in the number needed to screen 1 new case. Gender distribution was balanced within MC patients (Female/Male = 1.5/1), especially among lymphocytic colitis (Female/Male = 1.2/1). MC patients were negatively associated with the risk of neoplastic polyps compared with negative CNBD subjects (odds ratio = 0.22; P = 0.035).
  
  
  CONCLUSIONS
  MC is the first cause of CNBD in subjects submitted to colonoscopy. Multiple biopsies are strongly recommended, even in the case of uneventful endoscopic inspection, especially for age ≥40 years. MC has a reduced risk of colorectal neoplasia, suggesting that this model of chronic inflammation plays a protective effect against colorectal carcinogenesis.
authors.affiliation: *Gastroenterology and Digestive Endoscopy Unit, IRCCS Policlinico San Donato, San Donato Milanese, Italy; †Department of Medicine I, University of Erlangen-Nuremberg, Erlangen, Germany; ‡Department of Biomedical Sciences for Health, University of Milan, Milano, Italy; §Gastroenterology and Digestive Endoscopy Unit, Istituti Clinici Zucchi, Monza, Italy; ‖Pathology and Citodiagnostic Unit, IRCCS Policlinico San Donato, San Donato Milanese, Italy; and ¶Medical Department, Chiesi Farmaceutici SpA, Parma, Italy.
authors.forename: Gian Eugenio
authors.initials: GE
authors.lastname: Tontini
authors.forename: Luca
authors.initials: L
authors.lastname: Pastorelli
authors.forename: Luisa
authors.initials: L
authors.lastname: Spina
authors.forename: Federica
authors.initials: F
authors.lastname: Fabris
authors.forename: Barbara
authors.initials: B
authors.lastname: Bruni
authors.forename: Claudio
authors.initials: C
authors.lastname: Clemente
authors.forename: Germana
authors.initials: G
authors.lastname: de Nucci
authors.forename: Flaminia
authors.initials: F
authors.lastname: Cavallaro
authors.forename: Stefano
authors.initials: S
authors.lastname: Marconi
authors.forename: Markus F
authors.initials: MF
authors.lastname: Neurath
authors.forename: Helmut
authors.initials: H
authors.lastname: Neumann
authors.forename: Milena
authors.initials: M
authors.lastname: Tacconi
authors.forename: Maurizio
authors.initials: M
authors.lastname: Vecchi
mesh_terms: D000230:Adenocarcinoma / Q000175:diagnosis / Q000209:etiology / Q000517:prevention & control*; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001706:Biopsy; D016022:Case-Control Studies; D002908:Chronic Disease; D046729:Colitis, Collagenous / Q000150:complications* / Q000473:pathology; D046730:Colitis, Lymphocytic / Q000150:complications* / Q000473:pathology; D046728:Colitis, Microscopic / Q000150:complications* / Q000473:pathology; D003113:Colonoscopy; D015179:Colorectal Neoplasms / Q000175:diagnosis / Q000209:etiology / Q000517:prevention & control*; D003967:Diarrhea / Q000209:etiology* / Q000473:pathology; D004724:Endoscopy; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D011446:Prospective Studies; D012307:Risk Factors; D055815:Young Adult