The Asboe-Hansen sign (blister extension on lateral pressure) is positive in pemphigus vulgaris. What does it reflect at the tissue level?
- A Subepidermal split with fibrin deposition
- B Acantholysis spreading through the still-intact epidermis on pressure ✓
- C Dermal oedema causing fluid dissection
- D Basement membrane detachment
Correct answer: B. Acantholysis spreading through the still-intact epidermis on pressure
Explanation
Asboe-Hansen sign reflects acantholysis—loss of intercellular cohesion—spreading laterally within the epidermis when pressure is applied to an intact bulla. Because the acantholytic process is not yet complete in adjacent skin, pressure extends the cleavage plane. This is distinct from Nikolsky's sign (blister or erosion from friction on normal skin) but both indicate intraepidermal fragility. Subepidermal disorders like pemphigoid do not show Asboe-Hansen sign.
Reference: Neena Khanna Illustrated Synopsis of Dermatology & STD, 6th ed.
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