Explanation:
Osteosarcoma is defined by malignant tumor cells that directly produce osteoid matrix. This feature distinguishes it from other bone malignancies histologically. The tumor commonly arises in the metaphysis of long bones, particularly around the knee. Radiographic features include sunburst pattern and Codman's triangle. It most frequently affects adolescents during periods of rapid growth. Management typically includes neoadjuvant chemotherapy followed by surgical resection. Reference: Dorfman HD. "Osteosarcoma." Human Pathology, 1995.