Toward a Molecular-Genetic Classification of Spitzoid Neoplasms.

The histopathologic spectrum of Spitzoid neoplasms includes Spitz nevi, atypical Spitz tumors, and Spitzoid melanomas. Advances in molecular genetics have evolved to the point that Spitzoid lesions can now be reasonably classified according to their distinctive molecular-genetic alterations: Spitzoid lesions with (1) 11p amplification and/or HRAS mutations; (2) isolated loss of 6q23 by fluorescence in situ hybridization (FISH); (3) homozygous deletion of 9p21 by FISH; (4) BAP1 loss and BRAFV600 E mutation; (5) translocations involving any of a number of different oncogenic kinase drivers, including ROS1, ALK, NTRK1, NTRK3, MET, BRAF, and RET; and (6) TERT promoter mutations.