Data on somatic heterogeneity and germline-somatic interaction in multiple primary melanoma (MPM) patients are limited. We investigated the mutational status of BRAF, NRAS, and TERT promoter genes in 97 melanomas of 44 MPM patients and compared molecular and immunohistochemical findings. We further evaluated the association of somatic alterations with the germline MC1R genotype. Mutations in BRAF gene were identified in 41.2% (40/97) of melanomas, in NRAS in 2.1% (2/97), and in TERT promoter in 19.6% (19/97). Distribution of BRAF mutations did not differ across multiple melanomas (P = 0.85), whereas TERT promoter changes decreased from first to subsequent melanomas (P = 0.04). Intrapatient discrepancy of BRAF mutations among multiple tumors was detected in 14 of 44 MPM patients (32%) and of BRAF/NRAS/TERT promoter genes in 20 of 44 (45%). We observed a high rate of agreement between allele-specific TaqMan assay and immunohistochemistry in BRAF detection (κ = 0.83, P < 0.01) with 86 of 97 melanomas (88.7%) presenting similar BRAF status. Germline MC1R variants were identified in 81.4% (35/43) of MPM patients with no association of MC1R genotype with somatic mutations or with intrapatient concordance of somatic mutational profile. Our results support the genetic diversity of multiple melanomas and show that somatic heterogeneity is not influenced by inherited MC1R variants. Immunohistochemistry may be useful as an initial screening test.

Genetic susceptibility to cutaneous melanoma has been investigated in Italian high-risk melanoma patients from different geographical regions. CDKN2A, CDK4, and MC1R genes have been screened in most studies, MITF and POT1 were screened in only one study, and none analyzed the TERT promoter. We carried out a mutational analysis of CDKN2A, CDK4 exon 2, POT1 p.S270N, MITF exon 10, MC1R, and the TERT promoter in 106 high-risk patients with familial melanoma (FM) and sporadic multiple primary melanoma (spMPM) from Central Italy and evaluated mutations according to the clinicopathological characteristics of patients and lesions. In FM, CDKN2A mutations were detected in 8.3% of the families, including one undescribed exon 1β mutation (p.T31M), and their prevalence increased with the number of affected relatives within the family. MC1R variants were identified in 65% of the patients and the TERT rs2853669 promoter polymorphism was identified in 58% of the patients. A novel synonymous mutation detected in MITF exon 10 (c.861A>G, p.E287E), although predicted as a splice site mutation by computational tools, could not functionally be confirmed to alter splicing. For spMPM, 3% carried CDKN2A mutations, 79% carried MC1R variants, and 47% carried the TERT rs2853669 promoter polymorphism. MC1R variants were associated with fair skin type and light hair color both in FM and in spMPM, and with a reduction of age at diagnosis in FM patients. Mutations in CDK4 exon 2 and the POT1 p.S270N mutation were not detected. A low frequency of CDKN2A mutations and a high prevalence of MC1R variants characterize high-risk melanoma patients from Central Italy.

Background: Germline variants in MC1R may increase risk of childhood/adolescent melanoma, but a clear conclusion is challenging because of the limited number of studies and cases. We evaluated the association of MC1R variants and childhood/adolescent melanoma in a large study comparing the prevalence of MC1R variants of childhood/adolescent melanoma patients to that among adult melanoma cases and unaffected controls. Methods: Phenotypic and genetic data on 233 childhood/adolescent (≤20 years) and 932 adult melanoma patients, and 932 unaffected controls, were gathered through the M-SKIP Project, the Italian Melanoma Intergroup and European centers. We calculated odds ratios (OR) for childhood/adolescent melanoma associated with MC1R variants by multivariable logistic regression. Subgroup analysis was done for children aged ≤18 and ≤14 years. Findings: Children and adolescents had a higher odds of carrying MC1R r variants than adults (OR:1•54; 95%CI:1•02-2•33), also when analysis was restricted to cases ≤18 years (OR:1•80; 95%CI:1•06-3•07). All the investigated variants except R160W showed a higher frequency in childhood/adolescent melanoma compared to adult melanoma, with significant results for V60L (OR:1•60; 95%CI:1•05-2•44) and D294H (OR:2•15; 95%CI:1•05-4•40). Compared to unaffected controls, childhood/adolescent melanoma patients had significantly higher frequencies of any MC1R variants.. Interpretation: Our pooled-analysis of childhood/adolescent patients with MC1R genetic data revealed that MC1R r variants were more prevalent in childhood/adolescent compared to adult melanoma especially in children ≤18 years. Our findings support the role of MC1R in childhood/adolescent melanoma susceptibility with a potential clinical relevance in developing early melanoma detection and preventive strategies.

Background The association of clinical and dermoscopic features with BRAF mutational status has been poorly analysed in multiple primary melanomas (MPM). Objective To investigate whether concordance of BRAF mutational status is associated with dermoscopic similarity in multiple melanomas of the same patient. Methods 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 BRAFV600 mutational status was analysed with allele‐specific TaqManTM assays or pyrosequencing. Spearman's correlation and univariate and multivariate regression analysis were used for statistical analysis. Results 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 BRAFV600 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). Conclusion Dermoscopic similarity of multiple melanomas represents an independent clinical predictor of a concordant BRAF mutational status in MPM patients.

No abstract