Papulosquamous disorders: pachyonychia congenita: 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: pachyonychia congenita

Sample item

A child has thick, yellow, dystrophic nails, painful plantar keratoderma, white oral plaques and multiple small cysts. Which keratin defect usually underlies this condition?

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

The answer and the reasoning

A. Keratin 6 with keratin 16 or 17

Pachyonychia congenita is caused by mutations in keratins 6a, 6b, 16 or 17 and combines nail thickening, painful plantar keratoderma and oral leukokeratosis. Type 2 includes steatocystomas, from keratin 17.

Option by option

  • A. Keratin 6 with keratin 16 or 17 (correct)

    Correct. Keratins 6 with 16 or 17 are defective in pachyonychia congenita.

  • B. Keratin 9

    Keratin 9 mutations cause epidermolytic palmoplantar keratoderma, without dystrophic nails.

  • C. Keratin 5 with keratin 14

    Keratin 5 and 14 mutations cause epidermolysis bullosa simplex.

  • D. Keratin 1 with keratin 10

    Keratin 1 and 10 mutations cause epidermolytic hyperkeratosis.

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 A, Keratin 6 with keratin 16 or 17. Pachyonychia congenita is caused by mutations in keratins 6a, 6b, 16 or 17 and combines nail thickening, painful plantar keratoderma and oral leukokeratosis.

Why is "Keratin 9" not the answer?

Keratin 9 mutations cause epidermolytic palmoplantar keratoderma, without dystrophic nails.

Why is "Keratin 5 with keratin 14" not the answer?

Keratin 5 and 14 mutations cause epidermolysis bullosa simplex.

Why is "Keratin 1 with keratin 10" not the answer?

Keratin 1 and 10 mutations cause epidermolytic hyperkeratosis.

What concept does this question test?

It tests Papulosquamous disorders: pachyonychia congenita in Dermatology. Type 2 includes steatocystomas, from keratin 17.

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: pachyonychia congenita?

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.