Bone: osteoid osteoma: practice question

A Pathology 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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Pathology · Bone: osteoid osteoma

Sample item

A 14-year-old boy has tibial pain that is worse at night and dramatically relieved by aspirin. Radiograph shows a small radiolucent nidus less than 2 cm across, surrounded by dense cortical sclerosis. What accounts for the pain and its response to aspirin?

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

The answer and the reasoning

C. Locally produced prostaglandins from the nidus

Osteoid osteoma is a benign osteoblastic tumour of young people, usually in the cortex of long bones, and the nidus is rich in prostaglandins E2 and cyclooxygenase. These sensitise local nerve fibres, causing night pain that responds to NSAIDs. Treatment is CT-guided radiofrequency ablation or surgical excision, and a nidus larger than 2 cm suggests osteoblastoma.

Option by option

  • A. Raised intramedullary venous pressure

    Venous pressure is not the explanation for osteoid osteoma pain.

  • B. Systemic release of parathyroid hormone-related peptide

    PTHrP is released by some carcinomas and causes hypercalcaemia, not localised pain.

  • C. Locally produced prostaglandins from the nidus (correct)

    Correct. Nidus-derived prostaglandins cause the pain, and aspirin inhibits their synthesis.

  • D. Compression of a periosteal nerve by cortical expansion

    Nerve compression by expansion would not give a specific response to aspirin.

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.

More Pathology questions

Questions about this Pathology question

What is the answer to this Pathology question?

The best answer is C, Locally produced prostaglandins from the nidus. Osteoid osteoma is a benign osteoblastic tumour of young people, usually in the cortex of long bones, and the nidus is rich in prostaglandins E2 and cyclooxygenase.

Why is "Raised intramedullary venous pressure" not the answer?

Venous pressure is not the explanation for osteoid osteoma pain.

Why is "Systemic release of parathyroid hormone-related peptide" not the answer?

PTHrP is released by some carcinomas and causes hypercalcaemia, not localised pain.

Why is "Compression of a periosteal nerve by cortical expansion" not the answer?

Nerve compression by expansion would not give a specific response to aspirin.

What concept does this question test?

It tests Bone: osteoid osteoma in Pathology. These sensitise local nerve fibres, causing night pain that responds to NSAIDs. Treatment is CT-guided radiofrequency ablation or surgical excision, and a nidus larger than 2 cm suggests osteoblastoma.

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: osteoid osteoma?

Learn each disease as a bundle: cause, key histology, markers, and the clinical hallmark. Then use the flashcards and the other Pathology 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.