Osteosarcoma (osteogenic sarcoma) is the most common primary malignant bone tumor. The proliferating cells are capable of forming bone and osteoid (uncalcified bone matrix). Osteosarcomas are characterized by aggressive growth with severe bone and joint damage. They metastasize early hematogenously to the lungs. At the time of diagnosis 20% of patients already have metastases.Osteosarcomas occur mainly in the long bones (femur, humerus, tibia) of the skeletal system. 50% of osteosarcomas are located in close proximity to the knee joint. Male patients between 10 to 25 are mst commonly afflicted.
