Fungal infections: id 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 · Fungal infections: id reaction

Sample item

A patient with an inflamed tinea pedis develops itchy vesicles on the palms and sides of the fingers. A KOH smear from the palms is negative. What is the explanation?

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

The answer and the reasoning

B. Dermatophytid (id) reaction

An id reaction is a sterile eruption at a distant site triggered by a strongly inflamed fungal focus, a hypersensitivity response to fungal antigens. It clears when the primary infection is treated.

Option by option

  • A. Scabies

    Scabies would show burrows and positive scrapings.

  • B. Dermatophytid (id) reaction (correct)

    Correct. A sterile distant eruption following an inflamed tinea is an id reaction.

  • C. Fungal infection of the palms

    A direct palm infection would give a positive KOH.

  • D. Allergic contact dermatitis to gloves

    Contact dermatitis would follow exposure and not coincide with the tinea.

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 B, Dermatophytid (id) reaction. An id reaction is a sterile eruption at a distant site triggered by a strongly inflamed fungal focus, a hypersensitivity response to fungal antigens.

Why is "Scabies" not the answer?

Scabies would show burrows and positive scrapings.

Why is "Fungal infection of the palms" not the answer?

A direct palm infection would give a positive KOH.

Why is "Allergic contact dermatitis to gloves" not the answer?

Contact dermatitis would follow exposure and not coincide with the tinea.

What concept does this question test?

It tests Fungal infections: id reaction in Dermatology. It clears when the primary infection is treated.

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 Fungal infections: id 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.