Nikolsky's sign is a clinical dermatologicalsign, named after Pyotr Nikolsky (1858–1940), 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.[1][2][3][4] 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 (i.e., skin sloughed off), then the Nikolsky's sign is present/positive.
The formation of new blisters upon slight pressure (direct Nikolsky) and shearing of the skin due to rubbing (indirect Nikolsky) is a sign of pemphigus vulgaris, albeit not a 100% reliable diagnosis.[8] In addition, another physical exam, the Asboe-Hansen signs, must be used to determine the absence of intracellular connections holding epidermal cells together.[9]