Infections: Langerhans cell histiocytosis: 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 · Infections: Langerhans cell histiocytosis

Sample item

A 10-month-old has a persistent seborrhoeic-like eruption of the scalp and flexures with petechial crusted papules, hepatosplenomegaly and anaemia. Which test is most useful for diagnosis?

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

The answer and the reasoning

A. Skin biopsy with CD1a and langerin staining

Treatment-resistant seborrhoeic-like rash with petechiae and organomegaly in an infant raises Langerhans cell histiocytosis. Biopsy shows Langerhans cells positive for CD1a, S100 and langerin (CD207) with Birbeck granules on electron microscopy. Staging for multisystem disease follows.

Option by option

  • A. Skin biopsy with CD1a and langerin staining (correct)

    Correct. CD1a and langerin positivity on biopsy confirm Langerhans cell histiocytosis.

  • B. Serum IgE

    Raised IgE is non-specific and does not diagnose LCH.

  • C. Patch test

    Patch tests are for contact allergy.

  • D. Skin scraping for KOH

    KOH would address fungal disease, not this multisystem picture.

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, Skin biopsy with CD1a and langerin staining. Treatment-resistant seborrhoeic-like rash with petechiae and organomegaly in an infant raises Langerhans cell histiocytosis.

Why is "Serum IgE" not the answer?

Raised IgE is non-specific and does not diagnose LCH.

Why is "Patch test" not the answer?

Patch tests are for contact allergy.

Why is "Skin scraping for KOH" not the answer?

KOH would address fungal disease, not this multisystem picture.

What concept does this question test?

It tests Infections: Langerhans cell histiocytosis in Dermatology. Biopsy shows Langerhans cells positive for CD1a, S100 and langerin (CD207) with Birbeck granules on electron microscopy. Staging for multisystem disease follows.

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 Infections: Langerhans cell histiocytosis?

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.