The second patient had stage III BRAFV600R mutant melanoma that was treated with pembrolizumab and dabrafenib, and also developed a regressed melanocytic nevus.
BRAF mutations were more frequent in males, in young patients, and in tumours with a sun-exposed tumour location (bulbar conjunctiva or caruncle), with a mixed or non-pigmented colour, with absence of primary acquired melanosis, and with origin in a nevus.
Mutations of the BRAF gene are correlated with younger age, a higher number of melanocytic naevi and a tumour location in intermittently UV-exposed skin.
BRAF(V600E) mutations are also present in benign melanocytic naevi, highlighting the importance of additional genetic alterations in the genesis of malignant tumours.
Both Spitz naevi and spitzoid melanoma had a lower combined BRAF and NRAS mutation frequency compared with common acquired naevi (P = 0.0001) and common forms of melanoma (P = 0.0072), respectively.
GCMN and MCMN did not show oncogenic BRAF mutation and displayed similar features with respect to the amount of nonmelanocytic cells within the naevus and matrix architecture.
A similar high frequency (62-72%) of BRAF oncogenic mutations was identified in melanocytic nevi, VGP, metastatic melanomas, and melanoma cell lines [H. Davies et al., Nature (Lond.), 417: 949-954, 2002; P. M. Pollock et al., Nat.
Most melanocytic nevi develop on sun-exposed skin during childhood and adolescence and commonly harbor BRAF mutations or, less frequently, NRAS mutations.
To investigate whether the frequency of the BRAF(V600E) (V-raf murine sarcoma virus oncogene homolog B1) mutation in melanocytic nevi is associated with sun exposure patterns, we examined 120 acquired melanocytic nevi excised from various anatomic sites, including glabrous skin, as well as 62 congenital nevi.
They were ulcerated (p = 0.0001), they were associated with neurotropism (p = 0.0001), they lacked the BRAF mutation (p = 0.03), and they less often coexisted with a preceding melanocytic nevus (p = 0.0001).