Dermatology: aplasia cutis 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 · Dermatology: aplasia cutis congenita

Sample item

A newborn has a 2 cm well-demarcated, ulcerated, hairless scalp defect at the vertex surrounded by a ring of darker, longer hair. What does this ring suggest, and what should be done?

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

The answer and the reasoning

B. Hair collar sign, suggesting an underlying neural tube defect; image the underlying brain and spine

Aplasia cutis congenita is a congenital absence of skin, commonly at the scalp vertex. A ring of long dark hair around the lesion (hair collar sign) can signal an underlying neural tube defect, so neuroimaging is advised. Small lesions heal with conservative care.

Option by option

  • A. Normal variant; no investigation needed

    Investigation is needed because of possible neural tube defect.

  • B. Hair collar sign, suggesting an underlying neural tube defect; image the underlying brain and spine (correct)

    Correct. The hair collar sign calls for imaging.

  • C. Tinea capitis; start griseofulvin

    Tinea capitis is not present at birth.

  • D. Neonatal herpes; start acyclovir

    Herpes would show vesicles in an unwell infant.

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, Hair collar sign, suggesting an underlying neural tube defect; image the underlying brain and spine. Aplasia cutis congenita is a congenital absence of skin, commonly at the scalp vertex.

Why is "Normal variant; no investigation needed" not the answer?

Investigation is needed because of possible neural tube defect.

Why is "Tinea capitis; start griseofulvin" not the answer?

Tinea capitis is not present at birth.

Why is "Neonatal herpes; start acyclovir" not the answer?

Herpes would show vesicles in an unwell infant.

What concept does this question test?

It tests Dermatology: aplasia cutis congenita in Dermatology. A ring of long dark hair around the lesion (hair collar sign) can signal an underlying neural tube defect, so neuroimaging is advised. Small lesions heal with conservative care.

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 Dermatology: aplasia cutis 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.