Question

a 12-year-old male patient presents with chief complaint of right knee pain. you note swelling overlying the right knee. radiographic examination of the region reveals an osteoblastic lesion in the metaphysis of the distal femur with spiculated periosteal reactions. the lesion extends into the soft tissues. what is the most likely diagnosis?
a) fibrosarcoma
b) osteosarcoma
c) ewing sarcoma
d) chondrosarcoma

Explanation:

Osteosarcoma is the most common primary bone cancer in adolescents, typically arising in the metaphyseal region of long bones like the distal femur. Key radiologic features include osteoblastic (bone-forming) lesions, spiculated periosteal reactions (often described as a "sunburst" appearance), and extension into adjacent soft tissues, which match the patient's presentation. Fibrosarcoma is rare in this age group and usually has a lytic pattern. Ewing sarcoma more commonly presents with a permeative lytic lesion and is more frequent in flat bones or diaphyses of long bones. Chondrosarcoma is rare in children and produces chondroid (cartilage-forming) lesions.

Answer:

B) osteosarcoma