SITE VARIATIONS IN PATCH TEST RESPONSES ON THE BACK

To establish the existence of intra-regional variations in response to allergens on the back, we performed patch tests in 21 patients at 2 different sites on the back. Visual readings using the numerical scale established by the International Contact Dermtitis Research Group were carried out 2 days after application of the allergen. After each visual reading, the skin blood flow at the test sites was quantified by laser Doppler flowmetry. The results of laser Doppler flowmetry showed a highly significant difference between the upper and lower back. It is therefore necessary that in quantitative and comparative investigations, symmetrical sites, i.e., left versus right sides of the body, should be studied.