Are We Overtreating Severely Dysplastic Nevi?

What the Research Tells Us

Graeme M. Lipper, MD


April 21, 2017

Dysplastic Nevi With Severe Atypia: Long-term Outcomes in Patients With and Without Re-excision

Engeln K, Peters K, Ho J, et al
J Am Acad Dermatol. 2017;76:244-249


Dysplastic nevi (DN) are characterized by clinical asymmetry with irregular borders and color variegation, and histologically with architectural disorder and variable degrees of melanocytic cytologic atypia. Dermatopathologists typically use these histopathologic features to grade "gray area" melanocytic neoplasms as mild, moderate, or severe. However, agreement among dermatopathologists is surprisingly low, ranging from 35% to 58%.[1]

A 1992 National Institutes of Health Consensus Conference on early melanoma[2] recommended re-excision of DN with 0.2- to 0.5-cm margins, while a more recent (2015) guideline by the Melanoma Prevention Working Group (MPWG)[3] recommended observation for mildly to moderately atypical DN and excision for severely dysplastic nevi (SDN), even when margins are clear.

Excision of DN is prompted by an uncertain malignancy potential and the fear of undertreating an evolving malignant melanoma (MM), but re-excised DN are rarely upgraded histologically to MM; data show that this happens in 0%-2.7% of cases.[4] In contrast, a consensus has evolved that mildly to moderately DN should be clinically followed rather than excised due to the negligible risk for recurrent or metastatic disease, even in cases with positive margins.[5]

Consistent with the 2015 recommendations by the MPWG, most severely dysplastic nevi (SDN) are re-excised, even when margins are negative. But is this necessary or overtreatment?

Study Summary

To address this practical question, Engeln and colleagues retrospectively analyzed the long-term clinical outcomes in 451 adult patients (mean age, 41.3 years; 47% male) diagnosed with at least one SDN over a 10-year period. Highlights of their findings are as follows:

  • Of patients with SDN, 36.6% underwent re-excision.

  • Among the 63.4% with SDN who did not undergo re-excision, no cases of locally MM or recurrent MM developed over a mean follow-up period of 11.9 years.

  • Among the 165 patients who underwent re-excision of their SDN, two were diagnosed with melanoma at the original site (one had positive margins on original biopsy, and margin status of the other was unknown).

  • MM developed in seven patients after being diagnosed with SDN; however, all of these patients had had a prior invasive MM.

  • Margin comments influenced the decision to re-excise. Re-excision occurred in:

    • 23.1% of cases with negative margins

    • 46% of cases described as "margins free but close"

    • 57.9% of cases with positive margins

  • SDN read by a fellowship-trained dermatologist was more likely to result in re-excision compared with that read by a surgical pathologist (P = .033)


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