Definition: A usually aggressive malignant bone-forming mesenchymal tumor, predominantly affecting adolescents and young adults. It usually involves bones and less frequently extraosseous sites. It often involves the long bones (particularly distal femur, proximal tibia, and proximal humerus). Pain with or without a palpable mass is the most frequent clinical symptom. It may spread to other anatomic sites, particularly the lungs.
Synonyms (terms occurring on more labels are shown first): osteosarcoma, osteogenic sarcoma