A 65-year-old man presents with a progressive, painful swelling around the knee. X-ray shows a large lytic and calcified mass arising from the proximal tibia with a cartilaginous matrix showing rings-and-arcs calcification. Biopsy shows malignant chondrocytes with hyperchromatic nuclei in a chondroid matrix. Compared to osteosarcoma, what is the key therapeutic implication?

• A It responds well to neoadjuvant chemotherapy
• B It requires radical amputation
• C It is treated with bisphosphonates alone
• D It is relatively chemoresistant and radioresistant, so surgery is the mainstay ✓

Explanation

Chondrosarcoma in older adults shows rings-and-arcs calcification from cartilaginous matrix. Unlike osteosarcoma and Ewing sarcoma, chondrosarcoma is characteristically resistant to both chemotherapy and radiotherapy, making wide surgical excision the primary curative treatment. This distinction is repeatedly tested in postgraduate exams.

Reference: Campbell's Operative Orthopaedics, 14th ed.

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Written and medically reviewed by the StethoPrep medical team.