title: Factors influencing the agreement on histopathological assessments of breast biopsies among pathologists.
abstract: OBJECTIVE
  It has been recommended that the histopathology results of core biopsies of the breast are categorized according to the B-categorization scheme. We measured the interobserver variability of the B-categorization of core biopsies of the breast.
  
  
  RESULTS
  Core biopsies were taken among 765 women at the University of Halle between 2006 and 2008. All histological slides were reviewed in a blinded fashion by two experienced breast pathologists. We calculated observed and chance-corrected agreements (kappa) and 95% confidence intervals (CI). The prevalence of B3-B5 biopsies was 41.6%. The observed and weighted kappa agreement of the five-level B-categorization scheme was 0.87 (95% CI: 0.84 -0.89) and 0.89 (95% CI: 0.89-0.91), respectively. The most frequent disagreement was between B2 and B3 (47 of 103 disagreements, 45.6%). Overall, 49.5% of all disagreements were clinically relevant disagreements that would imply different therapeutic strategies. Agreement was modified by referral group, Breast Imaging Reporting and Data System (BIRADS) level, radiological breast density, imaging guidance and application of immunohistological staining.
  
  
  CONCLUSIONS
  Interobserver agreement of the B-categorization scheme was high and was modified by referral status, level of radiological suspicion of breast cancer, breast density, imaging guidance of core biopsies and requirement of additional immunohistological staining.
authors.affiliation: Institut für Klinische Epidemiologie, Medizinische Fakultät, Martin-Luther-Universität Halle-Wittenberg, Halle (Saale), Germany. andreas.stang@medizin.uni-halle.de
authors.forename: Andreas
authors.initials: A
authors.lastname: Stang
authors.forename: Pietro
authors.initials: P
authors.lastname: Trocchi
authors.forename: Kathrin
authors.initials: K
authors.lastname: Ruschke
authors.forename: Andrea
authors.initials: A
authors.lastname: Schmidt-Pokrzywniak
authors.forename: Hans-Jürgen
authors.initials: HJ
authors.lastname: Holzhausen
authors.forename: Thomas
authors.initials: T
authors.lastname: Löning
authors.forename: Jörg
authors.initials: J
authors.lastname: Buchmann
authors.forename: Christoph
authors.initials: C
authors.lastname: Thomssen
authors.forename: Tillmann
authors.initials: T
authors.lastname: Lantzsch
authors.forename: Steffen
authors.initials: S
authors.lastname: Hauptmann
authors.forename: Werner
authors.initials: W
authors.lastname: Böcker
authors.forename: Alexander
authors.initials: A
authors.lastname: Kluttig
mesh_terms: D001943:Breast Neoplasms / Q000145:classification* / Q000175:diagnosis*; D005260:Female; D006801:Humans; D008875:Middle Aged; D060787:Neoplasm Grading; D015588:Observer Variation; D010338:Pathology, Clinical / Q000592:standards*