NRAS and melanoma: Considering the 34 paired samples with discrepancies in BRAF/NRAS mutation patterns between primary and secondary tumors, majority of them (18; 53%) displayed a wild-type primary tumor and a mutated metastasis (14 in BRAF and 4 in NRAS), a second large fraction of cases (14/34; 41%) presented with a mutated primary tumor and a wild-type metastasis (13 in BRAF and 1 in NRAS), and the remaining limited subgroup of samples (2/34; 6%) carried a change in mutation pattern between the two tumor lesions (an NRAS mutation in primary melanoma and a BRAF mutation in melanoma metastasis) (Table 5).