Genodermatoses: incontinentia pigmenti: 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 · Genodermatoses: incontinentia pigmenti

Sample item

A newborn girl has linear vesicles and blisters along Blaschko lines on the limbs, with peripheral eosinophilia. Her mother has patchy hypodontia. Which statement is true?

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

The answer and the reasoning

B. X-linked dominant inheritance, usually lethal in males

Incontinentia pigmenti is X-linked dominant due to IKBKG (NEMO) mutation and is usually lethal in males. Skin lesions evolve through vesiculobullous, verrucous, hyperpigmented swirl and atrophic stages along Blaschko lines. Eye, tooth and central nervous system abnormalities can occur.

Option by option

  • A. Always limited to skin

    Systemic involvement of eyes, teeth and brain occurs.

  • B. X-linked dominant inheritance, usually lethal in males (correct)

    Correct. It is X-linked dominant and generally male-lethal.

  • C. Caused by a collagen VII defect

    Collagen VII defects cause dystrophic EB.

  • D. Autosomal recessive inheritance affecting both sexes equally

    Inheritance is not autosomal recessive.

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, X-linked dominant inheritance, usually lethal in males. Incontinentia pigmenti is X-linked dominant due to IKBKG (NEMO) mutation and is usually lethal in males.

Why is "Always limited to skin" not the answer?

Systemic involvement of eyes, teeth and brain occurs.

Why is "Caused by a collagen VII defect" not the answer?

Collagen VII defects cause dystrophic EB.

Why is "Autosomal recessive inheritance affecting both sexes equally" not the answer?

Inheritance is not autosomal recessive.

What concept does this question test?

It tests Genodermatoses: incontinentia pigmenti in Dermatology. Skin lesions evolve through vesiculobullous, verrucous, hyperpigmented swirl and atrophic stages along Blaschko lines. Eye, tooth and central nervous system abnormalities can occur.

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 Genodermatoses: incontinentia pigmenti?

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.