Papulosquamous disorders: pityriasis rotunda: 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: pityriasis rotunda

Sample item

A dark-skinned adult has several sharply demarcated, perfectly round, hyperpigmented scaly patches on the trunk, measuring 5 to 15 cm. They are asymptomatic. Which condition is this?

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

The answer and the reasoning

D. Pityriasis rotunda

Pityriasis rotunda causes well-defined circular scaly patches of ichthyosiform scale, mainly in Black, Asian and South African people. It can be associated with systemic disease such as hepatocellular carcinoma or TB, so a basic screen is advised.

Option by option

  • A. Nummular eczema

    Nummular eczema is itchy and made of coin-shaped weeping plaques.

  • B. Tinea versicolor

    Tinea versicolor gives smaller coalescing macules with fine scale and a positive KOH smear.

  • C. Pityriasis rosea

    Pityriasis rosea has a herald patch and oval lesions following skin cleavage lines.

  • D. Pityriasis rotunda (correct)

    Correct. Large, round, scaly, sharply bordered patches without symptoms are typical of pityriasis rotunda.

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, Pityriasis rotunda. Pityriasis rotunda causes well-defined circular scaly patches of ichthyosiform scale, mainly in Black, Asian and South African people.

Why is "Nummular eczema" not the answer?

Nummular eczema is itchy and made of coin-shaped weeping plaques.

Why is "Tinea versicolor" not the answer?

Tinea versicolor gives smaller coalescing macules with fine scale and a positive KOH smear.

Why is "Pityriasis rosea" not the answer?

Pityriasis rosea has a herald patch and oval lesions following skin cleavage lines.

What concept does this question test?

It tests Papulosquamous disorders: pityriasis rotunda in Dermatology. It can be associated with systemic disease such as hepatocellular carcinoma or TB, so a basic screen is advised.

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 Papulosquamous disorders: pityriasis rotunda?

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.