Musculoskeletal imaging: osteoblastoma: practice question

A Radiology 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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Radiology · Musculoskeletal imaging: osteoblastoma

Sample item

A 17-year-old has back pain and a painful scoliosis. CT shows an expansile lesion with a mineralised nidus of about 3 cm in the posterior elements of a thoracic vertebra. Pain is only partly relieved by aspirin. Which tumour is most likely?

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

The answer and the reasoning

B. Osteoblastoma

Osteoblastoma resembles osteoid osteoma histologically but has a nidus larger than 1.5 cm, is more expansile, and has less response to aspirin. It favours the posterior elements of the spine.

Option by option

  • A. Aneurysmal bone cyst

    Aneurysmal bone cyst is expansile but contains fluid-fluid levels and no mineralised nidus.

  • B. Osteoblastoma (correct)

    Correct. A nidus larger than 1.5 cm in the spinal posterior elements with a poor aspirin response indicates osteoblastoma.

  • C. Osteoid osteoma

    Osteoid osteoma has a nidus under 1.5 cm and pain classically relieved by aspirin.

  • D. Osteosarcoma

    Osteosarcoma shows aggressive periosteal reaction and a permeative pattern, usually in the long-bone metaphysis.

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 Radiology question

What is the answer to this Radiology question?

The best answer is B, Osteoblastoma. Osteoblastoma resembles osteoid osteoma histologically but has a nidus larger than 1.

Why is "Aneurysmal bone cyst" not the answer?

Aneurysmal bone cyst is expansile but contains fluid-fluid levels and no mineralised nidus.

Why is "Osteoid osteoma" not the answer?

Osteoid osteoma has a nidus under 1.5 cm and pain classically relieved by aspirin.

Why is "Osteosarcoma" not the answer?

Osteosarcoma shows aggressive periosteal reaction and a permeative pattern, usually in the long-bone metaphysis.

What concept does this question test?

It tests Musculoskeletal imaging: osteoblastoma in Radiology. 5 cm, is more expansile, and has less response to aspirin. It favours the posterior elements of the spine.

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 Musculoskeletal imaging: osteoblastoma?

Learn signs with the image, and the disease they point to. Then use the flashcards and the other Radiology 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.