A teenage patient with classical osteosarcoma receives neoadjuvant chemotherapy before limb salvage surgery. Histopathological examination of the resected specimen shows 95% tumour necrosis. What is the significance of this finding?
- A Indicates a poor response; chemotherapy regimen should be changed postoperatively
- B Indicates a good histological response (Huvos Grade IV) associated with improved disease-free survival ✓
- C Mandates amputation rather than limb salvage
- D Suggests misdiagnosis as the true osteosarcoma rarely responds to chemotherapy
Correct answer: B. Indicates a good histological response (Huvos Grade IV) associated with improved disease-free survival
Explanation
The Huvos grading system evaluates tumour necrosis after neoadjuvant chemotherapy: Grade III is 90–99% necrosis and Grade IV is 100% necrosis. Greater than 90% necrosis constitutes a good histological response, which is the single strongest predictor of improved 5-year disease-free and overall survival in osteosarcoma. A poor response (<90% necrosis) prompts consideration of changing the postoperative regimen, not a good response.
Reference: Maheshwari Essential Orthopaedics, 6th ed.
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