A Mutational Survey of Acral Nevi.

ABSTRACT

IMPORTANCE Acral skin may develop nevi, but their mutational status and association with acral melanoma is unclear. OBJECTIVE: To perform targeted next-generation sequencing on a cohort of acral nevi to determine their mutational spectrum. DESIGN, SETTING, AND PARTICIPANTS: Acral nevi specimens (n = 50) that had been obtained for diagnostic purposes were identified from the pathology archives of a tertiary care academic cancer center and a university dermatology clinic. Next-generation sequencing was performed on DNA extracted from the specimens, and mutations called. A subset of samples was stained immunohistochemically for the BRAF V600E mutation. RESULTS: A total of 50 nevi from 49 patients (19 males and 30 females; median [range] age, 48 [13-85] years) were examined. Analysis of the sequencing data revealed a high prevalence of BRAF mutations (n = 43), with a lower frequency of NRAS mutations (n = 5). Mutations in BRAF and NRAS were mutually exclusive. CONCLUSIONS AND RELEVANCE In this cohort study, nevi arising on mostly sun-protected acral skin showed a rate of BRAF mutation similar to that of acquired nevi on sun-exposed skin but far higher than that of acral melanoma. These findings are in contrast to the well-characterized mutational landscape of acral melanoma.