Fluorescence In Situ Hybridization for Melanoma Diagnosis: A Review and a Reappraisal.

Although conventional histopathological examination is the undisputable mainstay for the diagnosis of melanocytic skin neoplasms, fluorescence in situ hybridization (FISH) has the potential to provide important information to morphologically challenging cases. The standard melanoma FISH test targeting RREB1 (6p25), MYB (6q23), CCND1 (11q13), and centromere 6 is an effective compromise between cost, technical complexity, and sensitivity. The authors use the standard FISH-positivity as a tie-breaker for challenging melanocytic neoplasms mainly in a non-Spitzoid morphologic context because the currently available test leaves several unresolved issues: namely, a relatively low diagnostic accuracy in morphologically ambiguous melanocytic neoplasms; a relatively low sensitivity and specificity in Spitzoid neoplasms; and the occurrence of false positives due to tetraploidy in Spitz nevi and in nevi with an atypical epithelioid component.