FGFR1 and osteosarcoma: The RUL tumor with classic osteosarcoma morphology at year 7 had overlapping alterations with the previously described RML tumor, including TP53 and FGFR1 mutations, as well as CDKN2A loss, and it also did not harbor the ALK fusion (confirmed by RNAseq, FISH, and IHC).