title: Review article: Microscopic colitis--lymphocytic, collagenous and 'mast cell' colitis.
abstract: BACKGROUND
  Microscopic colitis is a relatively common cause of chronic diarrhoea in predominantly older adults, traditionally termed lymphocytic colitis and collagenous colitis. Increased mast cells found in the colonic biopsies of some patients with chronic diarrhoea may represent a distinct type of microscopic colitis.
  
  
  OBJECTIVE
  To provide an updated review of the epidemiology, diagnosis and treatment of microscopic colitis, and to discuss the role of mast cells in the gastrointestinal tract and their potential role in cases of functional diarrhoea.
  
  
  METHODS
  A MEDLINE literature search was performed to identify pertinent articles. Relevant clinical abstracts were also reviewed.
  
  
  RESULTS
  Incidence rates of microscopic colitis (lymphocytic and collagenous colitis) have increased over time, to levels comparable with other forms of inflammatory bowel disease. The possibility of drug-induced microscopic colitis and concomitant coeliac sprue are important considerations when evaluating these patients. There are few controlled treatment trials in microscopic colitis, with much of the data on treatment coming from retrospective studies. Mast cells have been implicated in functional bowel disorders, with increased mast cells possibly contributing to cases of otherwise unexplained chronic diarrhoea, although this concept requires further investigation.
  
  
  CONCLUSIONS
  In patients with microscopic colitis, a systematic approach to therapy often leads to satisfactory control of symptoms. The role of mast cells in chronic diarrhoea represents an evolving field, with the potential to offer alternative treatment pathways in patients with otherwise unexplained functional diarrhoea.
authors.affiliation: Division of Gastroenterology, University of Chicago, Pritzker School of Medicine, NorthShore University HealthSystem, Evanston, IL, USA. eyen@uchicago.edu
authors.forename: E F
authors.initials: EF
authors.lastname: Yen
authors.forename: D S
authors.initials: DS
authors.lastname: Pardi
mesh_terms: D046728:Colitis, Microscopic / Q000175:diagnosis / Q000188:drug therapy* / Q000453:epidemiology / Q000473:pathology; D003967:Diarrhea / Q000188:drug therapy* / Q000209:etiology; D005260:Female; D006801:Humans; D008297:Male; D008407:Mast Cells / Q000473:pathology*; D012074:Remission Induction; D012307:Risk Factors