title: Immunohistochemical classification of ductular reactions in human liver.
abstract: OBJECTIVE
  Ductular reactions occur in a wide variety of liver diseases. Their origin and function is still debated. Our understanding of these histological reactions is impaired by their great diversity; therefore rational classification should precede further detailed analysis. The aim was to achieve a reproducible classification of hepatic ductular reactions based on their immunophenotype.
  
  
  RESULTS
  Sixty-nine liver specimens with ductular reactions were analysed by immunohistochemistry. The majority of the samples could be classified into three categories based on their immunophenotype. Type P(rimitive) reaction is characterized by CD56 immunoreactivity. Most primary biliary cirrhosis and focal nodular hyperplasia samples fall into this group; these ductules do not show any sign of differentiation. Type D(ifferentiating) ductules are positive for CD56, epithelial membrane antigen (EMA) and CD10. Cirrhotic samples and regenerating livers following fulminant hepatic failure contain such ductular reactions; this immunophenotype indicates hepatocytic differentiation. Biliary obstruction results in EMA-positive type O(bstructive) reactions; these ductules are similar to the normal interlobular bile ducts.
  
  
  CONCLUSIONS
  Ductular reactions can be classified based on their immunophenotype. Our results may initiate further, similar, studies resulting in a generally accepted rational classification. We believe that such categorization is necessary for elucidating their biological and clinical significance.
authors.affiliation: First Department of Pathology and Experimental Cancer Research, Semmelweis University, Budapest, Hungary.
authors.forename: Eszter
authors.initials: E
authors.lastname: Turányi
authors.forename: Katalin
authors.initials: K
authors.lastname: Dezsö
authors.forename: Judit
authors.initials: J
authors.lastname: Csomor
authors.forename: Zsuzsa
authors.initials: Z
authors.lastname: Schaff
authors.forename: Sándor
authors.initials: S
authors.lastname: Paku
authors.forename: Péter
authors.initials: P
authors.lastname: Nagy
mesh_terms: D006500:Hepatic Duct, Common / Q000378:metabolism / Q000473:pathology*; D006801:Humans; D007150:Immunohistochemistry / Q000592:standards*; D008107:Liver Diseases / Q000145:classification* / Q000378:metabolism / Q000473:pathology*