A 17-year-old male has knee pain and a destructive metaphyseal lesion of the distal femur on X-ray with aggressive periosteal reaction showing a 'sunburst' pattern and 'Codman's triangle'. MRI shows extension through the cortex into the soft tissues. These findings are MOST consistent with:
- A Osteosarcoma (conventional osteosarcoma) ✓
- B Ewing's sarcoma
- C Giant cell tumour
- D Aneurysmal bone cyst
Explanation
Conventional osteosarcoma is the most common primary malignant bone tumour in adolescents (peak 10–25 years) and has a predilection for the metaphysis of long bones, especially the distal femur, proximal tibia, and proximal humerus. Classic radiological features include an aggressive destructive metaphyseal lesion with osteoid matrix (cloud-like density), sunburst periosteal reaction, Codman's triangle (periosteal elevation by tumour), and cortical breach with soft tissue mass. Ewing's sarcoma typically affects the diaphysis and shows onion-skin periosteal reaction. GCT is epiphyseal in skeletally mature patients.
Reference: Grainger & Allison's Diagnostic Radiology, 7th ed.
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Written and medically reviewed by the StethoPrep medical team.