title: Use of the WHO lymphoma classification in a population-based epidemiological study.
abstract: BACKGROUND
  Non-Hodgkin's lymphoma (NHL) is pathologically diverse. Epidemiological investigations into its increasing incidence and aetiology require accurate subtype classification.
  
  
  METHODS
  Available pathology reports of 717 cases aged from 20 to 74 years in an Australian, population-based epidemiological study of NHL were reviewed by one anatomical pathologist to assign a World Health Organization (WHO) classification category. High or low confidence was assigned to the diagnosis of NHL, cell phenotype and WHO category and reasons given for low confidence.
  
  
  RESULTS
  The most informative biopsy reports were from open tissue biopsy (79% of cases), tissue core biopsy (8%), cytology (4%) and bone marrow (9%); 8% of cases had inadequate biopsies for diagnostic purposes. Immunohistochemistry or flow cytometry reports were available for 96% of cases, gene rearrangement studies for 6% and cytogenetics for 3%. The reviewer assigned high confidence to the diagnosis of NHL in 93% of cases and also the phenotype in 88%. While a WHO classification could be assigned in 91% of cases, confidence was high in only 57.5%; insufficient immunophenotyping was the commonest reason for low confidence.
  
  
  CONCLUSIONS
  Expert pathology review of a population-based sample of NHL can provide a WHO classification category for most cases. A high level of confidence in the classification, however, would require review of diagnostic material and additional phenotyping.
authors.affiliation: Department of Anatomical Pathology, St Vincent's Hospital, Sydney, NSW, Australia. jturner@stvincents.com
authors.forename: J J
authors.initials: JJ
authors.lastname: Turner
authors.forename: A M
authors.initials: AM
authors.lastname: Hughes
authors.forename: A
authors.initials: A
authors.lastname: Kricker
authors.forename: S
authors.initials: S
authors.lastname: Milliken
authors.forename: A
authors.initials: A
authors.lastname: Grulich
authors.forename: J
authors.initials: J
authors.lastname: Kaldor
authors.forename: B
authors.initials: B
authors.lastname: Armstrong
mesh_terms: D000328:Adult; D000368:Aged; D001315:Australia / Q000453:epidemiology; D006801:Humans; D008223:Lymphoma / Q000145:classification* / Q000175:diagnosis; D008228:Lymphoma, Non-Hodgkin / Q000145:classification* / Q000175:diagnosis; D008875:Middle Aged; D014944:World Health Organization