Leprosy: Fernandez reaction: practice question

A Dermatology 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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Dermatology · Leprosy: Fernandez reaction

Sample item

After an intradermal injection of lepromin, which reaction is read at 48 to 72 hours and reflects delayed hypersensitivity to antigens of the bacillus?

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

The answer and the reasoning

D. Fernandez reaction

The early (Fernandez) reaction appears as erythema and induration at 48 to 72 hours and is a tuberculin-like delayed hypersensitivity response, so it indicates previous sensitisation. The late (Mitsuda) reaction, read at 21 days, reflects the ability to form a granuloma and has prognostic value.

Option by option

  • A. Mitsuda reaction

    The Mitsuda reaction is the late nodule read at about 21 days.

  • B. Frei reaction

    The Frei test is an intradermal test that was used for lymphogranuloma venereum.

  • C. Mantoux reaction

    The Mantoux test uses tuberculin purified protein derivative and not lepromin.

  • D. Fernandez reaction (correct)

    Correct. The 48 to 72 hour lepromin response is the Fernandez reaction.

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 Dermatology question

What is the answer to this Dermatology question?

The best answer is D, Fernandez reaction. The early (Fernandez) reaction appears as erythema and induration at 48 to 72 hours and is a tuberculin-like delayed hypersensitivity response, so it indicates previous sensitisation.

Why is "Mitsuda reaction" not the answer?

The Mitsuda reaction is the late nodule read at about 21 days.

Why is "Frei reaction" not the answer?

The Frei test is an intradermal test that was used for lymphogranuloma venereum.

Why is "Mantoux reaction" not the answer?

The Mantoux test uses tuberculin purified protein derivative and not lepromin.

What concept does this question test?

It tests Leprosy: Fernandez reaction in Dermatology. The late (Mitsuda) reaction, read at 21 days, reflects the ability to form a granuloma and has prognostic value.

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 Leprosy: Fernandez reaction?

Learn each condition by its primary lesion, site and signature sign. Then use the flashcards and the other Dermatology 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.