Immunology: drug-induced lupus: practice question

A Microbiology 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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Microbiology · Immunology: drug-induced lupus

Sample item

A 62-year-old man on long-term procainamide for ventricular arrhythmia develops fever, arthralgia and pleuritic chest pain. Antinuclear antibody is positive. Renal function and the central nervous system are normal. Which antibody is most characteristic of his condition?

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

The answer and the reasoning

C. Anti-histone antibody

Drugs such as procainamide, hydralazine and isoniazid can cause a lupus-like illness with arthralgia, serositis and fever. Anti-histone antibodies are found in over 90% of cases, whereas anti-dsDNA is uncommon and nephritis and neuropsychiatric disease are rare. It usually resolves after the drug is stopped.

Option by option

  • A. Anti-U1 ribonucleoprotein antibody

    Anti-U1 RNP is the marker of mixed connective tissue disease.

  • B. Anti-Smith antibody

    Anti-Smith antibody is highly specific for idiopathic systemic lupus erythematosus.

  • C. Anti-histone antibody (correct)

    Anti-histone antibodies are the hallmark of drug-induced lupus.

  • D. Anti-double-stranded DNA antibody

    Anti-dsDNA is typical of idiopathic lupus with nephritis and is usually absent in the drug-induced form.

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 Microbiology questions

Questions about this Microbiology question

What is the answer to this Microbiology question?

The best answer is C, Anti-histone antibody. Drugs such as procainamide, hydralazine and isoniazid can cause a lupus-like illness with arthralgia, serositis and fever.

Why is "Anti-U1 ribonucleoprotein antibody" not the answer?

Anti-U1 RNP is the marker of mixed connective tissue disease.

Why is "Anti-Smith antibody" not the answer?

Anti-Smith antibody is highly specific for idiopathic systemic lupus erythematosus.

Why is "Anti-double-stranded DNA antibody" not the answer?

Anti-dsDNA is typical of idiopathic lupus with nephritis and is usually absent in the drug-induced form.

What concept does this question test?

It tests Immunology: drug-induced lupus in Microbiology. Anti-histone antibodies are found in over 90% of cases, whereas anti-dsDNA is uncommon and nephritis and neuropsychiatric disease are rare. It usually resolves after the drug is stopped.

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 Immunology: drug-induced lupus?

Make a one-line identity card for each organism: shape and stain, defining test, toxin, disease and drug. Then use the flashcards and the other Microbiology 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.