title: Hepatoblastoma: assessment of criteria for histologic classification.
abstract: BACKGROUND
  Comparison of outcomes in different clinicopathologic studies of hepatoblastoma requires reproducible histologic classification. This review examines the diagnostic criteria employed by different pathologists for the classification of subtypes of hepatoblastoma and identifies specific problem areas.
  
  
  METHODS
  A selected review of published literature is provided.
  
  
  RESULTS
  Published studies demonstrate that uniform criteria have not been applied in the classification of hepatoblastoma. These discrepancies hinder attempts to compare outcome data from different studies. Sampling error and potential treatment effects further complicate analysis of the published literature on the relationship between morphologic classification and outcome.
  
  
  CONCLUSIONS
  Standardized criteria are essential to allow reproducible histologic classification of hepatoblastoma. There is significant variation in diagnostic criteria used to define the major subtypes of hepatoblastoma in published studies. Additional potential problems are identified in sampling methods and treatment effects.
authors.affiliation: Department of Pathology, Children's Hospital, Oakland, California 94609, USA. Jrowland@mail.cho.org
authors.forename: Jon M
authors.initials: JM
authors.lastname: Rowland
mesh_terms: D002648:Child; D002965:Classification; D018197:Hepatoblastoma / Q000145:classification* / Q000473:pathology*; D006652:Histological Techniques / Q000592:standards*; D006801:Humans; D008113:Liver Neoplasms / Q000145:classification* / Q000473:pathology*; D017410:Practice Guidelines as Topic