RREB1 and spitz nevus: Fluorescence in-situ hybridization (FISH) utilizing probes for genes RREB1 (6p25), cMYC (8q24), CDKN2A (p16)/CEN9, and CCND1 (11q13) has been shown to be sensitive and specific for differentiating Spitz nevi from spitzoid appearing melanoma.