Rheumatology: cryoglobulinaemic vasculitis: practice question

A General Medicine 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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General Medicine · Rheumatology: cryoglobulinaemic vasculitis

Sample item

A 55-year-old man with untreated chronic hepatitis C has palpable purpura on the legs, arthralgia and new haematuria with proteinuria. Which laboratory pattern is most expected?

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

The answer and the reasoning

C. Very low C4 with a positive rheumatoid factor and detectable cryoglobulins

Chronic hepatitis C drives mixed (type II) cryoglobulinaemia, in which a monoclonal IgM with rheumatoid factor activity binds polyclonal IgG, forming immune complexes that fix complement through the classical pathway. C4 is typically markedly low, and the typical manifestations are purpura, arthralgia, neuropathy and membranoproliferative glomerulonephritis. Treatment is antiviral therapy, with rituximab for severe vasculitis.

Option by option

  • A. Raised C4 with positive anti-CCP antibodies

    Anti-CCP marks rheumatoid arthritis and a raised C4 would not accompany immune complex consumption.

  • B. Normal complement levels with positive PR3-ANCA

    PR3-ANCA with normal complement describes granulomatosis with polyangiitis, a pauci-immune vasculitis.

  • C. Very low C4 with a positive rheumatoid factor and detectable cryoglobulins (correct)

    Correct. Classical pathway consumption with an IgM rheumatoid factor characterises hepatitis C cryoglobulinaemia.

  • D. Low C3 with high-titre anti-dsDNA antibodies

    Low C3 with anti-dsDNA suggests lupus nephritis rather than a virus-driven cryoglobulinaemic syndrome.

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 General Medicine question

What is the answer to this General Medicine question?

The best answer is C, Very low C4 with a positive rheumatoid factor and detectable cryoglobulins. Chronic hepatitis C drives mixed (type II) cryoglobulinaemia, in which a monoclonal IgM with rheumatoid factor activity binds polyclonal IgG, forming immune complexes that fix complement through the classical pathway.

Why is "Raised C4 with positive anti-CCP antibodies" not the answer?

Anti-CCP marks rheumatoid arthritis and a raised C4 would not accompany immune complex consumption.

Why is "Normal complement levels with positive PR3-ANCA" not the answer?

PR3-ANCA with normal complement describes granulomatosis with polyangiitis, a pauci-immune vasculitis.

Why is "Low C3 with high-titre anti-dsDNA antibodies" not the answer?

Low C3 with anti-dsDNA suggests lupus nephritis rather than a virus-driven cryoglobulinaemic syndrome.

What concept does this question test?

It tests Rheumatology: cryoglobulinaemic vasculitis in General Medicine. C4 is typically markedly low, and the typical manifestations are purpura, arthralgia, neuropathy and membranoproliferative glomerulonephritis. Treatment is antiviral therapy, with rituximab for severe vasculitis.

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 Rheumatology: cryoglobulinaemic vasculitis?

For each disease know the classic presentation, the best test, and the first-line treatment. Then use the flashcards and the other General Medicine 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.