title: Diagnostic concordance rates in the subtyping of basal cell carcinoma by different dermatopathologists.
abstract: BACKGROUND
  There are numerous subtypes of basal cell carcinoma (BCC). Defining the histopathologic subtype is an essential element in patient management, but there is little known data regarding interobserver precision in subtyping BCC.
  
  
  METHODS
  We studied interobserver variance between six board-certified dermatopathologists who subtyped 100 BCCs in a blinded fashion. We used kappa statistic to calculate the concordance in suggested subtype by different dermatopathologists. Provided diagnoses were then re-categorized into low-risk and high-risk phenotypes, and kappa statistic for concordance on high-risk BCC was determined.
  
  
  RESULTS
  The overall κ statistic was 0.301, indicating fair agreement among the six observers. Superficial and fibroepithelial BCC had the highest individual kappa statistics. When subtypes were re-classified into a two-tier system of high-risk and low-risk phenotypes, there was substantial interobserver agreement on high-risk BCC with a κ statistic of 0.699.
  
  
  CONCLUSIONS
  These results suggest only fair agreement among dermatopathologists on specific BCC subtypes, but substantial agreement on superficial, fibroepithelial and high-risk BCC growth patterns. A simplified classification system comprised of superficial, fibroepithelial, nodular and infiltrative subtypes would increase interobserver precision and facilitate clinical decision-making.
authors.affiliation: Department of Pathology and Laboratory Medicine, University of Kansas Medical Center, Kansas City, KS, USA.
authors.forename: Drew
authors.initials: D
authors.lastname: Nedved
authors.forename: Viseslav
authors.initials: V
authors.lastname: Tonkovic-Capin
authors.forename: Edgar
authors.initials: E
authors.lastname: Hunt
authors.forename: Nasir
authors.initials: N
authors.lastname: Zaidi
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Kucenic
authors.forename: Jeffery J
authors.initials: JJ
authors.lastname: Graves
authors.forename: Garth R
authors.initials: GR
authors.lastname: Fraga
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002280:Basal Cell Carcinoma / Q000145:classification / Q000473:pathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D015203:Reproducibility of Results; D012878:Skin Neoplasms / Q000145:classification / Q000473:pathology*
keywords: basal cell carcinoma; concordance; precision