Margin Assessment for Punch and Shave Biopsies of Dysplastic Nevi
July 2018 | Volume 17 | Issue 7 | Editorials | 810 | Copyright © July 2018
George A. Zakhem BS,a Vitaly Terushkin MD,a Euphemia W. Mu MD,a,b David Polsky MD PhD,a Shane A. Meehan MDa
aThe Ronald O. Perelman Department of Dermatology, New York University School of Medicine, New York, NY bMount Sinai Beth Israel, Department of Dermatologic Surgery, New York, NY
Introduction: 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.
Methods: 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.
Results: 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.
Conclusion: 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.
Biopsies of atypical melanocytic nevi are among the most commonly performed procedures by dermatologists. Once biopsied, specimens are examined by dermatopathologists for diagnosis, grading of atypia, and often the reporting of margins, all of which can be used to guide managment.1,2 Dysplastic nevi (DN) present a unique challenge to clinicians due to their uncertain biologic significance. While the presence of DN is a well-demonstrated melanoma risk factor, the risk of an individual lesion’s progression remains controversial––some evidence suggests a possibility of transformation to melanoma, but the proposed risk is quite low.3Given this unclear clinical significance, there are currently no standardized guidelines in the management of these lesions. However, dermatologists are more likely to recommend re-excision in cases with moderate or severe atypia and positive margins.1,2 Margin assessment 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. While Chang et al found 25% of punch biopsies interpreted as having negative margins are positive on further sectioning,4 no such estimate exists for shave biopsies, which are more commonly performed in community practices5 and may have lower rates of positive lateral margins than punch biopsies.6 In this study, the rates of false negative margins after both punch and shave biopsies were analyzed.
We performed a retrospective analysis of consecutive punch and shave biopsy specimens obtained from the NYU Dermatopathology repository. 50 consecutive cases were retrieved from the NYU Dermatopathology section archives that had been (1) diagnosed as DN, and (2) reported as having clear margins in the planes of section examined. Specimen removed by fusiform excision, those given a final diagnosis of non-melanocytic lesions or melanoma, and those without comments on margin status were excluded. Data on patient age, sex, race, degree of atypia, initial clinical diagnosis, and type of biopsy was collected for each specimen. The selected 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. Table 1 describes the clinical and pathologic characteristics for all specimens, while Table 2 compares those with true and false negative