Mastocytosis: 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 · Mastocytosis

Sample item

A 1-year-old has multiple reddish-brown macules and papules on the trunk. Stroking one lesion causes it to become raised, red and itchy within minutes, and the child sometimes flushes. What is this sign, and what does the biopsy show?

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

The answer and the reasoning

D. Darier's sign, with dermal collections of mast cells

Urticaria pigmentosa is the commonest form of cutaneous mastocytosis in children, with brown macules that urticate on rubbing (Darier's sign) because of mast cell degranulation and histamine release. Biopsy shows increased dermal mast cells, and most childhood cases resolve by adolescence.

Option by option

  • A. Koebner phenomenon, with parakeratosis

    The Koebner phenomenon is lesion formation at sites of trauma in psoriasis, vitiligo and lichen planus.

  • B. Nikolsky's sign, with acantholysis

    Nikolsky's sign shows epidermal separation, as in pemphigus.

  • C. Auspitz sign, with suprapapillary thinning

    The Auspitz sign is pinpoint bleeding on removal of psoriatic scale.

  • D. Darier's sign, with dermal collections of mast cells (correct)

    Correct. Urtication on stroking is Darier's sign in mastocytosis.

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, Darier's sign, with dermal collections of mast cells. Urticaria pigmentosa is the commonest form of cutaneous mastocytosis in children, with brown macules that urticate on rubbing (Darier's sign) because of mast cell degranulation and histamine release.

Why is "Koebner phenomenon, with parakeratosis" not the answer?

The Koebner phenomenon is lesion formation at sites of trauma in psoriasis, vitiligo and lichen planus.

Why is "Nikolsky's sign, with acantholysis" not the answer?

Nikolsky's sign shows epidermal separation, as in pemphigus.

Why is "Auspitz sign, with suprapapillary thinning" not the answer?

The Auspitz sign is pinpoint bleeding on removal of psoriatic scale.

What concept does this question test?

It tests Mastocytosis in Dermatology. Biopsy shows increased dermal mast cells, and most childhood cases resolve by adolescence.

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 Mastocytosis?

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.