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High Quantity of False Negatives Found in Biopsies

J Drugs Dermatol; 2018 Jul; Zakhem, Terushkin, et al

A recent study observed false negative peripheral margin status in a sizeable proportion of biopsy specimens, which did not vary significantly based on biopsy technique or pathologic characteristics. This finding reflects a limitation of standard tissue processing, in which a limited proportion of the true margin is evaluated, and may be of note to many dermatologists who base their decision to re-excise on the reporting of margin involvement. Researchers performed a retrospective analysis of 50 consecutive punch and shave biopsy specimens (1) diagnosed as dysplastic nevi (DN), and (2) reported as having clear margins in the planes of section examined. Identified specimen blocks were then sectioned through to examine true margin involvement. They found:

  • Of total specimens identified, 20% (n=10) were found to have positive margins upon additional sectioning.
  • There was no difference between the groups with respect to biopsy technique, type of nevus, degree of atypia, or gender.

Zakhem GA, Terushkin V, Mu EW, Polsky D, Meehan SA. Margin assessment for punch and shave biopsies of dysplastic nevi. J Drugs Dermatol. 2018;17(7):810-812.