Margin Assessment for Punch and Shave Biopsies of Dysplastic Nevi

Biopsies of atypical melanocytic nevi are among the most commonly performed procedures by dermatologists. Margin assessment is often used to guide re-excision, but can be a point of confusion as negative margins reported in the planes of sections examined do not always reflect complete removal of a lesion. This study investigates the rates of false negative margins after both punch and shave biopsies.

We performed a retrospective analysis of 50 consecutive punch and shave biopsy specimens (1) diagnosed as 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.

Of the 50 specimens identified, 20% (n = 10) were found to have positive margins upon additional sectioning. We found no difference between the groups with respect to biopsy technique, type of nevus, degree of atypia, or gender.

This 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. J Drugs Dermatol. 2018;17(7):810-812.