title: Predictive value of margins in diagnostic biopsies of nonmelanoma skin cancers.
abstract: BACKGROUND
  With geographic regional variation, nonmelanoma skin cancer biopsy reports include assessment of margins. When margins are reported as negative, clinical dilemmas may emerge concerning the necessity of additional treatment.
  
  
  OBJECTIVE
  To evaluate the predictive value of biopsy margins with regard to residual tumor present in subsequent excisions of nonmelanoma skin cancers.
  
  
  METHODS
  This is a retrospective review of 235 diagnostic nonmelanoma skin cancer biopsies and their corresponding excisions for margin status at biopsy, and the presence of residual tumor in subsequent excisions.
  
  
  RESULTS
  Twelve of 148 squamous cell carcinomas (8.1%) had negative biopsy margins and all of the subsequent excisions were free of residual tumor. The squamous cell carcinomas with negative biopsy margins consisted predominantly of nonfacial, superficial tumors of the well-differentiated and keratoacanthoma subtype. Nine of 87 basal cell carcinomas (10.3%) had negative biopsy margins. Seven of those 9 (77.8%) had residual tumor present in subsequent excisions.
  
  
  CONCLUSIONS
  Statistical analysis performed reached significance, but with small sample size as only 21 of the biopsy specimens had negative margins. Also, residual tumor was determined via standard bread-loafing technique on excisions, which is known to examine only a proportion of the tissue and can lead to false-negative results.
  
  
  CONCLUSIONS
  The results of this small pilot study suggest that negative-margin diagnostic biopsies may be therapeutic for well-differentiated or keratoacanthoma subtypes of squamous cell carcinoma because all subsequent excisions were devoid of tumor. Negative biopsy margins from basal cell carcinomas were not predictive of tumor removal.
authors.affiliation: Division of Dermatology, Department of Medicine, University of California Los Angeles School of Medicine, Los Angeles, California, USA. JEJackson@mednet.ucla.edu
authors.forename: Julie E
authors.initials: JE
authors.lastname: Jackson
authors.forename: Brent
authors.initials: B
authors.lastname: Kelly
authors.forename: Matthew
authors.initials: M
authors.lastname: Petitt
authors.forename: Tatsuo
authors.initials: T
authors.lastname: Uchida
authors.forename: Richard F
authors.initials: RF
authors.lastname: Wagner
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001706:Biopsy; D002280:Basal Cell Carcinoma / Q000175:diagnosis* / Q000473:pathology / Q000601:surgery; D002294:Carcinoma, Squamous Cell / Q000175:diagnosis* / Q000473:pathology / Q000601:surgery; D005260:Female; D006801:Humans; D007636:Keratoacanthoma / Q000175:diagnosis* / Q000473:pathology / Q000601:surgery; D008297:Male; D008875:Middle Aged; D018365:Neoplasm, Residual; D012878:Skin Neoplasms / Q000175:diagnosis* / Q000473:pathology / Q000601:surgery