A nongrading histologic approach to Clark (dysplastic) nevi: A potential to decrease the excision rate.

Abstract

Despite a lack of evidence that dysplastic nevi are precursors to melanoma, a large proportion of dermatologists continue to treat them as such. Emerging data suggest that histologic grading approach may result in many unnecessary excisions. Using a nongrading approach to diagnosis of Clark/dysplastic nevi, the current study sought to define and determine the diagnostic uncertainty rate, and to report on the results of re-excisions of such lesions. All melanocytic nevi submitted to an academic dermatopathology laboratory between January 1, 2007, and December 31, 2013, were categorized. The number of Clark nevi recommended for re-excision divided by the total number of Clark nevi was taken to be the diagnostic uncertainty rate. This nongrading approach resulted in an excision recommendation/diagnostic uncertainty rate of 11.1%. In 2% of the excised specimens, the diagnosis was changed to melanoma. The study was performed at a single institution, and assigned diagnoses could not be verified other than by the diagnosing dermatopathologists. Lesions that were not submitted as re-excision specimens could have altered the results had they been available for evaluation. Compared with previously reported excision rates, the current study shows that the nongrading approach to Clark nevi results in a lower excision rate while still maintaining a low rate of change in diagnosis similar to the grading approach.