Which sign is positive in Stevens-Johnson syndrome?

• A. Nikolsky sign.
• B. Tinel sign.
• C. Kernig sign.
• D. Babinski sign.

Answer: (A)

Stevens-Johnson syndrome features widespread damage to the skin and mucous membranes, making the epidermis unusually fragile. A positive Nikolsky sign fits this pattern: when gentle lateral pressure is applied to intact skin, the surface layer separates and can slide off, producing a blister or exfoliation. This occurs because keratinocytes undergo apoptosis and lose their adhesion in the superficial epidermis, leading to easy shearing of the skin.

The other signs are not related to this process. Tinel sign is a nerve irritability test used for conditions like carpal tunnel syndrome. Kernig sign is a meningeal irritation test. Babinski sign is a sign of upper motor neuron lesion. None of these reflect the widespread epidermal detachment seen in Stevens-Johnson syndrome.

So the sign that is positive in Stevens-Johnson syndrome is the Nikolsky sign.