Metastatic osteosarcoma to the liver after treatment for synovial sarcoma: a case report.

Metastatic osteosarcoma most commonly affects the lungs and other bones. Hepatic metastasis at the time of diagnosis is extremely rare. A 14-year-old boy with synovial sarcoma of the left popliteal fossa was treated with surgical resection, radiotherapy for microscopic residual disease, and 1 year of chemotherapy (vincristine, cyclophosphamide, dactinomycin, and doxorubicin). Approximately 10 years after the initial diagnosis, a secondary osteosarcoma developed in the left proximal tibia. Computed tomography at presentation showed bilateral pulmonary metastases and large ossified nodules in the liver that demonstrated abnormal avidity on 99mTc MDP bone scan indicating hepatic metastasis. Despite chemotherapy (cisplatin, ifosfamide, high-dose methotrexate, and dacarbazine), the patient died of progressive disease 4 months after the diagnosis of the second cancer. Hepatic metastasis was found at the time of diagnosis of a secondary osteosarcoma and manifested as ossified nodules. The risk of radiation-induced osteosarcoma should always be considered in decisions about treatment for soft-tissue sarcoma.