Which clinical or histologic feature is most characteristic of pemphigus vulgaris?

Which clinical or histologic feature is most characteristic of pemphigus vulgaris?

• A. Positive Nikolsky sign
• B. Subepidermal blister with eosinophils
• C. Tzanck smear showing multinucleated giant cells
• D. Negative Nikolsky sign

Answer: (A)

Pemphigus vulgaris is defined by loss of keratinocyte adhesion within the epidermis (acantholysis) due to autoantibodies against desmosomes. This makes the epidermis unusually fragile, so gentle rubbing or pressure can cause the superficial layer to detach, producing a blister—this is the positive Nikolsky sign. In a Tzanck smear, you’d expect acantholytic keratinocytes rather than multinucleated giant cells. Subepidermal blisters with eosinophils point to conditions like bullous pemphigoid, which are not intraepidermal. So the hallmark feature is the positive Nikolsky sign arising from intraepidermal acantholysis.

Pemphigus vulgaris is defined by loss of keratinocyte adhesion within the epidermis (acantholysis) due to autoantibodies against desmosomes. This makes the epidermis unusually fragile, so gentle rubbing or pressure can cause the superficial layer to detach, producing a blister—this is the positive Nikolsky sign. In a Tzanck smear, you’d expect acantholytic keratinocytes rather than multinucleated giant cells. Subepidermal blisters with eosinophils point to conditions like bullous pemphigoid, which are not intraepidermal. So the hallmark feature is the positive Nikolsky sign arising from intraepidermal acantholysis.