Bone tumours: dedifferentiated chondrosarcoma: practice question

A Orthopaedics question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Orthopaedics · Bone tumours: dedifferentiated chondrosarcoma

Sample item

A 66-year-old man has a long-standing painless pelvic cartilage lesion that suddenly enlarges and becomes painful. Histology shows a low-grade cartilage tumour abruptly juxtaposed with a high-grade spindle cell sarcoma. Which variant is this?

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

D. Dedifferentiated chondrosarcoma

Dedifferentiated chondrosarcoma combines a low-grade cartilage component with a sharply demarcated high-grade non-cartilaginous sarcoma. It has an aggressive course and a poor prognosis, and it is treated mainly by wide resection, as it responds poorly to chemotherapy.

Option by option

  • A. Clear cell chondrosarcoma

    Clear cell chondrosarcoma is an indolent tumour of the epiphysis, often in the femoral head.

  • B. Conventional grade 1 chondrosarcoma

    A conventional grade 1 tumour lacks a high-grade sarcoma component.

  • C. Mesenchymal chondrosarcoma

    Mesenchymal chondrosarcoma shows small blue cells with islands of cartilage, mainly in young adults.

  • D. Dedifferentiated chondrosarcoma (correct)

    Correct. An abrupt junction between low-grade cartilage and high-grade sarcoma defines this variant.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

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Questions about this Orthopaedics question

What is the answer to this Orthopaedics question?

The best answer is D, Dedifferentiated chondrosarcoma. Dedifferentiated chondrosarcoma combines a low-grade cartilage component with a sharply demarcated high-grade non-cartilaginous sarcoma.

Why is "Clear cell chondrosarcoma" not the answer?

Clear cell chondrosarcoma is an indolent tumour of the epiphysis, often in the femoral head.

Why is "Conventional grade 1 chondrosarcoma" not the answer?

A conventional grade 1 tumour lacks a high-grade sarcoma component.

Why is "Mesenchymal chondrosarcoma" not the answer?

Mesenchymal chondrosarcoma shows small blue cells with islands of cartilage, mainly in young adults.

What concept does this question test?

It tests Bone tumours: dedifferentiated chondrosarcoma in Orthopaedics. It has an aggressive course and a poor prognosis, and it is treated mainly by wide resection, as it responds poorly to chemotherapy.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Bone tumours: dedifferentiated chondrosarcoma?

Pair each fracture with its classic complication and nerve injured. Then use the flashcards and the other Orthopaedics questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.