Melanocytic proliferation constitutes a heterogeneous group of lesions with remarkable differences in their biology and clinical outcome. Thus, accurate histological diagnosis of these cases is mandatory to establish the most appropriate surgical treatment and follow-up. Although histological examination alone is usually sufficient to identify melanomas among the greater number of nevi, the definition of the benign or malignant nature of a subset of melanocytic tumours, exhibiting atypical features, is a challenging task. Novel techniques that may assist in the histopathological diagnosis in difficult cases have been extensively researched over recent years. Fluorescence in-situ hybridization (FISH), performed with a panel of four probes, including three locus-specific identifier (RREB1, MYB, and CCND1) genes, seems to represent a sensitive and specific molecular tool for the diagnosis of non-ambiguous melanocytic lesions. Some studies have agreed that FISH may be an ancillary diagnostic instrument, but cannot replace light microscopy, to distinguish benign nevi from malignant melanomas in daily practice. However, in the context of ambiguous melanocytic tumours, results are still controversial, and additional and substantial work is needed to develop reliable probes that may identify, with high sensitivity, specific subsets of ambiguous melanocytic lesions, including spitzoid proliferation.
© 2011 Blackwell Publishing Limited.