TP53 and osteosarcoma: De novo TP53 mutations can be found in 10%–20% of individuals with LFS; approximately 20% of these mutations seem to occur during embryogenesis.56 The most frequent tumors observed in children with LFS are osteosarcomas, adrenal cortical neoplasms, CNS tumors, and soft tissue tumors, with ERMS being the most frequent type in the latter category.57