Related Experiment Video
Updated: Mar 30, 2026
Author Spotlight: Genetically Engineered Mouse Models and Pathological Characterization of Neurofibromatosis Type 1 Associated Tumors
Published on: May 17, 2024
A nongrading histologic approach to Clark (dysplastic) nevi: A potential to decrease the excision rate
Daniel F Lozeau1, Michele J Farber1, Jason B Lee1
1Department of Dermatology and Cutaneous Biology, Thomas Jefferson University, Philadelphia, Pennsylvania.
Background:
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.
Objective:
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.
Methods:
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.
Results:
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.
Limitations:
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.
Conclusion:
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.
