Dermoscopic similarity is an independent predictor of BRAF mutational concordance in multiple melanomas

The association of clinical and dermoscopic features with BRAF mutational status has been poorly analysed in multiple primary melanomas (MPM).

To investigate whether concordance of BRAF mutational status is associated with dermoscopic similarity in multiple melanomas of the same patient.

Dermoscopic images and corresponding tissue sections of 124 melanomas from 62 patients with MPM were selected at four Italian Dermatology Departments. Similarity of dermoscopic appearance between multiple melanomas was evaluated according to the presence of the same prevalent dermoscopic feature. The BRAF^V600 mutational status was analysed with allele-specific TaqMan^TM assays or pyrosequencing. Spearman's correlation and univariate and multivariate regression analysis were used for statistical analysis.

A similar dermoscopic appearance was identified in 38.7% (24/62) of patients with MPM and was correlated with older age at first diagnosis (rho: 0.26; P: 0.042) and occurrence on sun-damaged skin (rho: 0.27; P: 0.037). The BRAF^V600 mutation was detected in 39.5% (49/124) of the tumors and a concordant BRAF mutational status between melanomas in 33/62 (53.2%) MPM patients. Dermoscopically similar melanomas showed 5.7-fold higher odds to be concordant for BRAF mutational status compared to dissimilar lesions (OR: 5.7; 95% CI 1.7-19.5; P: 0.005).

Dermoscopic similarity of multiple melanomas represents an independent clinical predictor of a concordant BRAF mutational status in MPM patients.