Dedifferentiated chondrosarcoma is a rare and aggressive variant in which a conventional chondrosarcoma transforms into a very high-grade tumour with a dismal prognosis. Chemotherapy sensitivity in this setting is uncertain; it is often managed along lines similar to osteosarcoma, though outcomes tend to be poorer.

Treatment approach (partial overview):

Management combines systemic multiagent chemotherapy with definitive en-bloc surgical resection. The choice of surgical approach is critically shaped by the achievability of adequate margins — further details, the full drug regimen, and the complete decision algorithm are available in the structured protocol.

References

DOI: 10.1093/annonc/mdq223

In rare circumstances conventional chondrosarcomas can 'dedifferentiate' into a very high-grade tumour with a dismal prognosis, so-called dedifferentiated chondrosarcoma.
There remains uncertainty about chemotherapy sensitivity of dedifferentiated chondrosarcoma but it is often treated like osteosarcoma, with poorer outcome.
There is a very high risk of local recurrence following excision of dedifferentiated chondrosarcoma, particularly in the presence of a pathological fracture.
If wide margins cannot be reliably achieved with limb salvage then amputation should be considered.

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Treatment of Chondrosarcoma in Dedifferentiated (High-Grade) Presentation

References