title: Misclassification of dysplasia in patients with inflammatory bowel disease: consequences for progression rates to advanced neoplasia.
abstract: BACKGROUND
  The natural behavior of flat low-grade (LGD) and indefinite dysplasia (IND) in patients with inflammatory bowel disease (IBD) remains uncertain and seems to be dependent on the interpretation of the pathologist. We studied the progression rate of flat LGD and IND to advanced neoplasia (high-grade dysplasia [HGD] or colorectal cancer [CRC]) before and after histopathological review by a panel of gastrointestinal expert pathologists.
  
  
  METHODS
  A nationwide pathology database was used to identify IBD patients with dysplasia in six Dutch university medical centers between 1990 and 2006. Medical charts of patients with recorded flat LGD or IND were reviewed. Histological slides from three university medical centers were reviewed by a panel of three expert gastrointestinal pathologists.
  
  
  RESULTS
  We identified 113 flat LGD patients and 26 flat IND patients. Advanced neoplasia was found in 18 flat LGD patients (16%) after a median follow-up of 48 months, resulting in a 5-year progression rate of 12%. Five IND patients (19%) developed advanced neoplasia after a median follow-up of 24 months, resulting in a 5-year progression rate of 21%. Review of 1547 histological slides from 87 patients resulted in an increase of the 5-year progression rate of flat LGD to advanced neoplasia to 37%, whereas the progression rate of IND decreased to 5%.
  
  
  CONCLUSIONS
  A diagnosis of flat LGD that is confirmed by a panel of expert gastrointestinal pathologists is associated with a substantial risk of progression to advanced neoplasia, while confirmed IND is associated with a low risk of progression.
authors.affiliation: University Medical Center Utrecht, Department of Gastroenterology and Hepatology, Utrecht, The Netherlands.
authors.forename: Fiona D M
authors.initials: FD
authors.lastname: van Schaik
authors.forename: Fiebo J W
authors.initials: FJ
authors.lastname: ten Kate
authors.forename: G Johan A
authors.initials: GJ
authors.lastname: Offerhaus
authors.forename: Marguerite E I
authors.initials: ME
authors.lastname: Schipper
authors.forename: Frank P
authors.initials: FP
authors.lastname: Vleggaar
authors.forename: C Janneke
authors.initials: CJ
authors.lastname: van der Woude
authors.forename: Pieter C F
authors.initials: PC
authors.lastname: Stokkers
authors.forename: Dirk J
authors.initials: DJ
authors.lastname: de Jong
authors.forename: Daan W
authors.initials: DW
authors.lastname: Hommes
authors.forename: Ad A
authors.initials: AA
authors.lastname: van Bodegraven
authors.forename: Peter D
authors.initials: PD
authors.lastname: Siersema
authors.forename: Bas
authors.initials: B
authors.lastname: Oldenburg
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D003093:Colitis, Ulcerative / Q000145:classification* / Q000453:epidemiology / Q000473:pathology*; D015179:Colorectal Neoplasms / Q000453:epidemiology / Q000473:pathology*; D003424:Crohn Disease / Q000145:classification* / Q000453:epidemiology / Q000473:pathology*; D016208:Databases, Factual; D018450:Disease Progression; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D011230:Precancerous Conditions / Q000145:classification / Q000453:epidemiology / Q000473:pathology; D012307:Risk Factors; D055815:Young Adult