"White dermographism" is seen in?

Ans. A. Atopic dermatitisWhite dermographism is seen in atopic dermatitis due to capillary vasoconstriction following light stroking of the skin.The small blood vessels in atopic dermatitis show a tendency to vasoconstriction responses.1. Pallor of the skin after stroking (white dermographism)2. Delayed blanch with acetylcholine3. White reaction to nicotinic acid esters4. Abnormal reactions to histamine in affected skin5. Low finger temperature6. Pronounced vasoconstriction on exposure to cold.None of these findings is pathognomonic.