title: Accuracy of biopsy sampling for subtyping basal cell carcinoma.
abstract: BACKGROUND
  Basal cell carcinoma (BCC) is a common skin cancer for which the treatment and recurrence risk correlate with the histologic subtype. Limited information is available regarding the accuracy of biopsy in diagnosing BCC subtypes.
  
  
  OBJECTIVE
  We sought to determine the correlation between BCC subtypes present in a biopsy specimen and the actual subtypes present in a tumor.
  
  
  METHODS
  In this retrospective study, skin biopsy specimens and corresponding excisions were reviewed. All histologic subtypes present in the biopsy specimen were reported and compared with the composite BCC subtype present in the biopsy specimen and excision.
  
  
  RESULTS
  A total of 232 biopsy specimens and corresponding wide excisions were examined. The biopsy specimen accuracy rate was 82% for punch and shave biopsy specimens. Mixed histologic subtypes were seen in 54% of the cases, half of which contained an aggressive subtype (infiltrative, morpheaform, or micronodular). There was an 18% discordance rate between the biopsy specimen subtype and the composite subtype. Importantly, 40% of these discordant cases (7% of all cases examined) had an aggressive subtype that was not sampled in the initial biopsy specimen. Furthermore, some cases were misidentified as infiltrative subtype in the biopsy specimen as a result of misinterpretation of surface ulceration and reactive stromal changes.
  
  
  CONCLUSIONS
  The limited number of punch biopsy specimens and the fact that Mohs excisions were not included are limitations.
  
  
  CONCLUSIONS
  Punch and shave biopsy specimens provided adequate sampling for correct BCC subtyping in 82% of the cases examined. However, 18% of the biopsy specimens were misidentified, some of which missed an aggressive component. Thus, there are potential pitfalls in the identification of BCC subtypes in biopsy specimens, which may have important implications in treatment outcome.
authors.affiliation: Department of Pathology and Immunology, Baylor College of Medicine, Houston, Texas 77030, USA.
authors.forename: Andrea L
authors.initials: AL
authors.lastname: Haws
authors.forename: Rafael
authors.initials: R
authors.lastname: Rojano
authors.forename: Steven R
authors.initials: SR
authors.lastname: Tahan
authors.forename: Thuy L
authors.initials: TL
authors.lastname: Phung
mesh_terms: D001706:Biopsy; D002280:Basal Cell Carcinoma / Q000145:classification / Q000473:pathology*; D006801:Humans; D012867:Skin / Q000473:pathology*; D012878:Skin Neoplasms / Q000145:classification / Q000473:pathology*