What's new in prognostication of melanoma in the dermatopathology laboratory?

With the advent of genetic and epigenetic research, molecular techniques could someday be used to discriminate nevus from melanoma so that ambiguous melanocytic lesions could be more accurately classified or that prognostication could be improved in melanoma patients. That promised day might be closer than realized. The last 20 years of research in cytogenetic and genetic alterations in melanoma have culminated in defined chromosomal lesions discriminating benign from malignant melanocytic tumors. Exploiting these differences, fluorescence in situ hybridization (FISH) can reproducibly discriminate unequivocal melanomas from melanocytic nevi with high sensitivity and specificity. The discriminating power of FISH in melanocytic tumors with ambiguous histopathology is questionable, however, because there is no standard definition of "malignancy." Additional FISH studies on ambiguous cases are needed through international collaborations where large collections of such cases are shared and the "proof of malignancy" is established by adequate clinical follow-up. This contribution reviews the diagnostic utility of DNA-based FISH technology as it compares the diagnostic accuracy in melanocytic tumors with unambiguous vs ambiguous histopathology. The melanoma epigenome is further characterized through research into various activities of small interfering RNAs, such as microRNAs, providing the pathway for the application of microRNA-based strategies that could be the basis for future diagnostic biomarkers and molecular therapies in melanoma.