Molecular testing in the diagnosis of melanocytic tumors

Fluorescent in situ hybridization (FISH) and comparative genomic hybridization (CGH) are molecular techniques that have become valuable adjuncts in the diagnosis of histopathologically ambiguous melanocytic tumors. These techniques detect the presence of chromosomal gains or losses that are characteristic of malignant transformation in melanocytic neoplasms. CGH and FISH have been used to characterize distinct genomic characteristics of melanocytic tumors at various anatomic sites and tumors with certain histopathologic features (e.g. spitzoid, blue nevus-like, congenital nevi). Recent developments in this field include the transition of CGH from a research tool to a clinically available test and a new FISH probe set targeting chromosomal loci 11q13, 8q24, 6p25 and 9p21 that reportedly distinguishes melanoma from melanocytic nevi with a sensitivity and specificity of 94% and 98% respectively. Genomic analysis of melanocytic tumors also provides prognostic information. This review discusses these new advances in molecular diagnostics in melanoma and future directions in the field.