Bone and joint infections: amyloidosis in chronic osteomyelitis: 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 and joint infections: amyloidosis in chronic osteomyelitis

Sample item

A 50-year-old man has had a discharging sinus from tibial osteomyelitis for 30 years. He now has heavy proteinuria and oedema, and a renal biopsy shows Congo red positive deposits. Which protein forms the deposits?

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

The answer and the reasoning

A. Serum amyloid A

Chronic inflammation raises serum amyloid A, the precursor of AA (secondary) amyloid, which deposits in the kidney and causes nephrotic syndrome. It is a recognised late complication of long-standing osteomyelitis, tuberculosis and rheumatoid arthritis.

Option by option

  • A. Serum amyloid A (correct)

    Correct. Chronic infection drives serum amyloid A production and secondary AA amyloidosis.

  • B. Transthyretin

    Transthyretin amyloid is hereditary or age-related and affects the heart and nerves.

  • C. Immunoglobulin light chain

    Light chain (AL) amyloid is associated with plasma cell disorders.

  • D. Beta-2 microglobulin

    Beta-2 microglobulin amyloid occurs in long-term dialysis patients.

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 A, Serum amyloid A. Chronic inflammation raises serum amyloid A, the precursor of AA (secondary) amyloid, which deposits in the kidney and causes nephrotic syndrome.

Why is "Transthyretin" not the answer?

Transthyretin amyloid is hereditary or age-related and affects the heart and nerves.

Why is "Immunoglobulin light chain" not the answer?

Light chain (AL) amyloid is associated with plasma cell disorders.

Why is "Beta-2 microglobulin" not the answer?

Beta-2 microglobulin amyloid occurs in long-term dialysis patients.

What concept does this question test?

It tests Bone and joint infections: amyloidosis in chronic osteomyelitis in Orthopaedics. It is a recognised late complication of long-standing osteomyelitis, tuberculosis and rheumatoid arthritis.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. 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 and joint infections: amyloidosis in chronic osteomyelitis?

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.