Figure 4. Atypical Spitz tumor with GTF3C2-ALK fusion arising from double minute formation.

A. Low-power view demonstrates a dome-shaped, predominantly intradermal melanocytic tumor with a bulbous base. B. FISH demonstrates multiple signals for the probe targeting the 3′ end of ALK (orange) scattered within the nuclei of melanocytes. C. Log₂ ratio along chromosome 2 obtained by CGH demonstrates a focal amplification (top). The amplicon is ~2 Mb long and is flanked by GTF3C2 and ALK (center). Reads that map to the breakpoints in GTF3C2 and ALK demonstrate unaligned regions that flank the breakpoint (rainbow colored, as viewed in Integrative Genomics Viewer).