Cutaneous blood flow during white dermographism in patients with atopic dermatitis.

Cutaneous blood flow was determined before and immediately after rubbing the skin of 7 patients with atopic dermatitis and 6 normal subjects, using the local atraumatic 133Xe-method. In the atopic patients the rubbing of eczematous skin produced white dermographism and simultaneously the cutaneous blood flow decreased in all the patients from 15.2 +/- SEM 1.7 ml/100 g . min before the rubbing to 6.2 +/- SEM 1.6 ml/100 g . min during white dermographism (p less than 0.002). In all the normal subjects the rubbing stimulus was followed by an increase in blood flow from 5.2 +/- SEM 0.6 to 24.4 +/- SEM 3.1 ml/100 g . min (p less than 0.001), although red dermographism was not seen in all. It is concluded that the most reasonable explanation for the pallor during white dermographism is the reduced cutaneous blood flow.