DICER1 and osteosarcoma: Notably, our case excluded DICER1 mutations (associated with pediatric central nervous system tumors) (25–27), EWSR1 rearrangements (a hallmark of Ewing sarcoma) (28), and MDM2 amplification (common in liposarcoma and osteosarcoma) (22), highlighting the molecular distinctiveness of HGMS.