Most Melanomas Are Not Related to Existing Nevi

Most instances of melanoma develop as new spots, and not from existing moles, according to the results of a recent study.
______________________________________________________________________________________________________________________________________________________________________

Reported rates of nevus-associated melanoma have varied significantly since the 1940s, ranging from as low as 4% to 72%, according to the researchers.

In their systematic review and meta-analysis of 38 observational cohort and case-control studies involving 20,126 melanomas, the researchers found that 29.1% of melanomas were associated with preexisting nevus while 70.9% were not, and any given melanoma was 64% less likely to be nevus-related that not.

Subanalyses revealed that nevus-associated melanomas had a lower mean Breslow thickness than those not associated with preexisting nevus, and no significant differences were observed between nondysplastic nevi and dysplastic nevi.

—Michael Potts

Reference:

Pampena R, Kyrgidis A, Lallas A, et al. A meta-analysis of nevus-associated melanoma: Prevalence and practical implications [published online August 29, 2017]. JAAD. http://dx.doi.org/10.1016/j.jaad.2017.06.149.