Nikolsky's sign
Nikolsky's sign is a clinical dermatological sign, named after Pyotr Nikolsky, a Russian physician who trained and worked in the Russian Empire. The sign is present when slight rubbing of the skin results in exfoliation of the outermost layer. A typical test would be to place the eraser of a pencil on the roof of a lesion and spin the pencil in a rolling motion between the thumb and forefinger. If the lesion is opened, then the Nikolsky's sign is present/positive.
Nikolsky's sign is almost always present in Stevens–Johnson syndrome/toxic epidermal necrolysis and staphylococcal scalded skin syndrome, caused by the exfoliative toxin of Staphylococcus aureus. It is also associated with pemphigus vulgaris and pemphigus foliaceus. It is useful in differentiating between the diagnosis of pemphigus vulgaris or mucous membrane pemphigoid and bullous pemphigoid.
The Nikolsky sign is dislodgement of intact superficial epidermis by a shearing force, indicating a plane of cleavage in the skin at the dermal-epidermal junction. The histological picture involves thinner, weaker attachments of the skin lesion itself to the normal skin – resulting in easier dislodgement.
The formation of new blisters upon slight pressure and shearing of the skin due to rubbing is a sign of pemphigus vulgaris, albeit not a 100% reliable diagnosis. In addition, another physical exam, the Asboe-Hansen signs, must be used to determine the absence of intracellular connections holding epidermal cells together.
