Papulosquamous disorders: erythema annulare centrifugum: 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 · Papulosquamous disorders: erythema annulare centrifugum

Sample item

A woman has a slowly enlarging annular erythematous ring on the thigh with a trailing scale on the inner edge. KOH is negative and the lesion is firm to palpate. What is the diagnosis?

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

The answer and the reasoning

B. Erythema annulare centrifugum

Erythema annulare centrifugum is a reactive annular erythema with scale trailing behind the advancing edge. It may follow infection, drugs or malignancy, and histology shows a perivascular coat-sleeve infiltrate.

Option by option

  • A. Granuloma annulare

    Granuloma annulare has smooth dermal papules without scale.

  • B. Erythema annulare centrifugum (correct)

    Correct. A trailing inner scale with a negative KOH favours erythema annulare centrifugum.

  • C. Erythema migrans

    Erythema migrans is a tick-bite expanding ring with central clearing and no scale.

  • D. Tinea corporis

    Tinea corporis has scale at the advancing edge and positive KOH.

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 annulare centrifugum. Erythema annulare centrifugum is a reactive annular erythema with scale trailing behind the advancing edge.

Why is "Granuloma annulare" not the answer?

Granuloma annulare has smooth dermal papules without scale.

Why is "Erythema migrans" not the answer?

Erythema migrans is a tick-bite expanding ring with central clearing and no scale.

Why is "Tinea corporis" not the answer?

Tinea corporis has scale at the advancing edge and positive KOH.

What concept does this question test?

It tests Papulosquamous disorders: erythema annulare centrifugum in Dermatology. It may follow infection, drugs or malignancy, and histology shows a perivascular coat-sleeve infiltrate.

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 Papulosquamous disorders: erythema annulare centrifugum?

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.