Reactive erythemas: erythema multiforme: 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 · Reactive erythemas: erythema multiforme

Sample item

A 22-year-old with recurrent cold sores develops symmetrical, round, 'target-shaped' lesions with a dusky centre on the palms and extensor surfaces, a week after a herpes labialis episode. Mucosal involvement is minimal. What is the diagnosis?

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

The answer and the reasoning

B. Erythema multiforme minor, most often triggered by herpes simplex virus

Erythema multiforme presents with acral target lesions with three zones of colour change, often after herpes simplex infection, and sometimes after Mycoplasma pneumoniae or drugs. It is self-limiting, and recurrent disease can be prevented with continuous antiviral prophylaxis. Extensive mucosal involvement suggests erythema multiforme major or SJS.

Option by option

  • A. Pityriasis rosea

    Pityriasis rosea has a herald patch and a Christmas-tree distribution on the trunk.

  • B. Erythema multiforme minor, most often triggered by herpes simplex virus (correct)

    Correct. Acral target lesions after HSV with minimal mucosal disease are classic.

  • C. Toxic epidermal necrolysis

    TEN causes widespread skin sloughing and not target lesions.

  • D. Urticaria

    Urticarial wheals are transient and migratory, lasting under 24 hours.

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, Erythema multiforme minor, most often triggered by herpes simplex virus. Erythema multiforme presents with acral target lesions with three zones of colour change, often after herpes simplex infection, and sometimes after Mycoplasma pneumoniae or drugs.

Why is "Pityriasis rosea" not the answer?

Pityriasis rosea has a herald patch and a Christmas-tree distribution on the trunk.

Why is "Toxic epidermal necrolysis" not the answer?

TEN causes widespread skin sloughing and not target lesions.

Why is "Urticaria" not the answer?

Urticarial wheals are transient and migratory, lasting under 24 hours.

What concept does this question test?

It tests Reactive erythemas: erythema multiforme in Dermatology. It is self-limiting, and recurrent disease can be prevented with continuous antiviral prophylaxis. Extensive mucosal involvement suggests erythema multiforme major or SJS.

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 Reactive erythemas: erythema multiforme?

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.