CGH evaluation of two de novo synchronous tumors in a child with a germline p53 mutation. We report the case of a child who developed two de novo synchronous tumors: an osteosarcoma and an embryonal rhabdomyosarcoma. The patient was determined to be a de novo carrier of a P53 germline mutation. Comparative genomic hybridization (CGH) analysis revealed that each of the neoplasms was characterized by a specific set of chromosomal imbalances and high-level amplification (HLA) regions. Our CGH findings provide evidence that cancer development is a cellular/organ specific event.