Vesiculobullous: salt-split skin in pemphigoid: 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: salt-split skin in pemphigoid

Sample item

Direct immunofluorescence of perilesional skin in a patient with tense bullae shows linear IgG and C3 along the basement membrane. On salt-split skin, the deposits localise to which side of the split?

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

The answer and the reasoning

A. The epidermal side (roof)

In bullous pemphigoid, antibodies to BP180 and BP230 sit in the hemidesmosome, so after salt splitting they stay on the epidermal roof. In epidermolysis bullosa acquisita and bullous SLE, deposits are on the dermal floor. Intercellular deposition is the pemphigus pattern.

Option by option

  • A. The epidermal side (roof) (correct)

    Correct. Pemphigoid antigens lie on the roof side of the salt-split.

  • B. Intercellular spaces of the epidermis

    Intercellular deposition is a fishnet pattern of pemphigus.

  • C. The dermal side (floor)

    Floor deposition is typical for EBA and anti-laminin gamma-1 pemphigoid.

  • D. Both sides equally

    Equal deposition does not characterise bullous pemphigoid.

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, The epidermal side (roof). In bullous pemphigoid, antibodies to BP180 and BP230 sit in the hemidesmosome, so after salt splitting they stay on the epidermal roof.

Why is "Intercellular spaces of the epidermis" not the answer?

Intercellular deposition is a fishnet pattern of pemphigus.

Why is "The dermal side (floor)" not the answer?

Floor deposition is typical for EBA and anti-laminin gamma-1 pemphigoid.

Why is "Both sides equally" not the answer?

Equal deposition does not characterise bullous pemphigoid.

What concept does this question test?

It tests Vesiculobullous: salt-split skin in pemphigoid in Dermatology. In epidermolysis bullosa acquisita and bullous SLE, deposits are on the dermal floor. Intercellular deposition is the pemphigus pattern.

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: salt-split skin in pemphigoid?

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.