When firm stroking of apparently normal-looking skin in a patient with atopic dermatitis produces a white line instead of the usual red flare, this phenomenon is termed:

• A Darier sign
• B Nikolsky sign
• C Koebner phenomenon
• D White dermographism ✓

Explanation

White dermographism, an exaggerated vasoconstrictor response producing blanching instead of the normal erythematous triple response, is characteristically seen in atopic dermatitis. Darier sign is the urtication of mastocytosis lesions on rubbing, Nikolsky sign indicates intraepidermal acantholysis, and Koebner phenomenon refers to lesion induction by trauma, seen in psoriasis and lichen planus.

Reference: Rook's Textbook of Dermatology, 9th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.