Reducing Excisions of Dysplastic Moles By Eliminating Grading

Jason B. Lee MD Professor , Clinical Vice Chair Department of Dermatology and Cutaneous Biology Director, Jefferson Dermatopathology Center Thomas Jefferson University Philadelphia, Pennsylvania

Dr. Jason Lee Interview with:
Jason B. Lee MD

Professor , Clinical Vice Chair
Department of Dermatology and Cutaneous Biology
Director, Jefferson Dermatopathology Center
Thomas Jefferson University
Philadelphia, Pennsylvania 

Medical Research: What is the background for this study? What are the main findings?

Dr. Lee: When initially described, Clark et al. suggested that dysplastic nevi were intermediate lesions that lie biologically on a spectrum between benign and malignant. As such, they were to be histologically graded as mild, moderate, and severe (or a combination thereof), with mild presumably closer to benign and severe closer to malignant. In this paradigm, adopted by most dermatologists, these nevi are routinely excised based on histologic grading and margin status. Recent outcomes of follow-up and excision studies of dysplastic nevi suggest that they are over treated as there have been very low rates of melanoma on re-excision.

An alternative approach considers dysplastic or eponymously Clark nevi as common acquired nevi, typically in fair skin individuals, and rejects the entire notion that they are intermediate lesions as there exists no formal proof of their intermediate status. This approach omits grading and margin status entirely, providing the clinician an explicit recommendation for excision only for those cases of diagnostic uncertainty. In this study, excision recommendation rate of dysplastic/Clark nevi was determined along with analysis of excision outcomes in a laboratory where non-grading histologic diagnostic approach to these nevi has been adopted.

The excision recommendation rate, representing the diagnostic uncertainty rate, was 11.1%. Out of 80% of the cases returned for excision, only 2.0% of the cases were interpreted as melanoma on excision; all were in situ or thin melanomas. This excision rate is much lower than in prior reports, which vary from 22-52%, while still capturing melanomas within this subset of lesions.

Medical Research: What should clinicians and patients take away from your report?

Dr. Lee: Histologic grading of dysplastic/Clark nevi reinforces the notion that these nevi are biologically intermediate lesions, exerting pressure on the clinician to excise them based on histologic grading and margin status. To date, however, there has been no formal proof of their biological intermediate status with recent review on the subject concluding that they represent markers of melanoma risk rather than direct precursors.* Their significance lies in the fact that they are significant simulators of early melanomas both clinically and histologically, imposing a diagnostic challenge for even the most experienced dermatologists and dermatopathologists. Thus, given that melanomas and dysplastic/Clark nevi share overlapping clinical and histologic features, an inherent margin of error exists in differentiating the two melanocytic neoplasms. The non-grading approach addresses this core issue of dysplastic/Clark nevus by recommending excision that is based on diagnostic uncertainty on the part of the dermatopathologist. Compared to the previously reported excision rates, the non-grading approach resulted in a lower excision rate while still maintaining a very low rate of change in diagnosis similar to that of the grading approach.

*DuffyK, Grossman D. The dysplastic nevus: from historical perspective to management in the modern era: part 1. Historical, histologic, and clinical aspects. J Am Acad Dermatol. 2012;67:1.e1-1.e16.

Medical Research: What recommendations do you have for future research as a result of this study?

Dr. Lee: While publications based on histologic grading approach to dysplastic nevus predominate, this study represents one of the few studies that are based on a non-grading histologic approach in the diagnosis of this relatively common nevus. Additional studies that corroborates with the results of this study are needed to lend further support to minimize the over biopsy and over treatment of dysplastic/Clark nevi that achieve the goal of better and more optimal management of patients who harbor these nevi.


J Am Acad Dermatol. 2016 Jan;74(1):68-74. doi: 10.1016/j.jaad.2015.09.030. Epub 2015 Nov 6.

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

Lozeau DF1, Farber MJ1, Lee JB2

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Jason B. Lee MD (2016). Reducing Excisions of Dysplastic Moles By Eliminating Grading 

Last Updated on January 5, 2016 by Marie Benz MD FAAD