Classic high-grade osteosarcoma is a highly malignant spindle-cell sarcoma of bone in which the malignant cells produce osteoid. It is the most common primary malignant tumor of bone, excluding myeloma, and is the third most common malignant disease in adolescence after leukemia and lymphoma. However, it is still a rare tumor with only 1000 new cases per year in the United States. There appears to be no racial or ethnic influence associated with its incidence. However, an increased prevalence has been noted in families affected with Li-Fraumeni syndrome and in patients who have had retinoblastoma (a 40% prevalence in those with bilateral disease), have undergone radiation therapy, or have Paget disease.