Vesiculobullous: SSSS versus TEN level of split: 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 · Vesiculobullous: SSSS versus TEN level of split

Sample item

A 2-year-old has fever, perioral crusting and widespread tender erythema with superficial peeling and sparing of the mouth. A skin biopsy would most likely show cleavage at which level?

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

The answer and the reasoning

C. Granular layer of the epidermis

Staphylococcal scalded skin syndrome results from exfoliative toxin cleaving desmoglein 1 in the granular layer, so the split is very superficial and mucosae are spared. In toxic epidermal necrolysis, full-thickness keratinocyte necrosis causes a subepidermal split with mucosal erosions. The distinction decides antibiotics versus drug withdrawal.

Option by option

  • A. Dermoepidermal junction with full-thickness necrosis

    Full-thickness necrosis at the junction describes TEN.

  • B. Sub-lamina densa

    A sub-lamina densa split characterises dystrophic epidermolysis bullosa.

  • C. Granular layer of the epidermis (correct)

    Correct. SSSS shows a granular-layer split with mucosal sparing.

  • D. Suprabasal layer

    A suprabasal split characterises pemphigus vulgaris.

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 C, Granular layer of the epidermis. Staphylococcal scalded skin syndrome results from exfoliative toxin cleaving desmoglein 1 in the granular layer, so the split is very superficial and mucosae are spared.

Why is "Dermoepidermal junction with full-thickness necrosis" not the answer?

Full-thickness necrosis at the junction describes TEN.

Why is "Sub-lamina densa" not the answer?

A sub-lamina densa split characterises dystrophic epidermolysis bullosa.

Why is "Suprabasal layer" not the answer?

A suprabasal split characterises pemphigus vulgaris.

What concept does this question test?

It tests Vesiculobullous: SSSS versus TEN level of split in Dermatology. In toxic epidermal necrolysis, full-thickness keratinocyte necrosis causes a subepidermal split with mucosal erosions. The distinction decides antibiotics versus drug withdrawal.

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 Vesiculobullous: SSSS versus TEN level of split?

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.