<prompt> Age group affected by osteosarcoma -upto 10 years10-20 years30 - 40 yearsOlder than 45 years  <response>: Ans. is b i.e., 10 - 20 years Osteogenic sarcoma is the most common primary malignant tumor of bone in children. This is predominantly a tumor of childhood or adolescence, occuring most commonly in the 10-25 years. The most common site of involvement is metaphysis of long bone around knee: - Lower end of femur 45 Upper end of Tibia 25 Other sites of involvement are proximal humerus 9, and very rarely radius and fibula. The usual presentation is local pain associated with gradually increasing swelling. On examination there may be local tenderness and warmth overlying skin. About 10 of patients have pulmonary metastasis by the time they first seen. 