Atopic dermatitis (AD) is primarily influenced by environmental factors including exposure to pollutants and indoor allergens (particularly, house dust mites). Al-though house dust mite antigens are the most prevalent components of indoor allergens in Korea, cockroaches also can be considered to act as an important allergen.

This study was done to evaluate the differences in three different atopic patch test (APT) techniques, and the relationship between APT and skin prick test, total IgE, and specific serum IgE level using cockroach allergen. Methods: We performed patch test in 57 patients with AD and 30 normal controls on clinically lesional and normal appearing skin with German cockroach (GC) allergens (extract, as is) in three different techniques (standard, scratch, DMSO). Reactions were evaluated after 48hours, and compared with the results of skin prick test, total and specific IgE levels. Detailed atopy history and severity scoring were taken.

In the GC (whole body) prick test positive group, there was 1263.02 IU/ml of total IgE, and this amount was significantly higher than GC (whole body) prick test negative group who had 549.46 IU/ml (P<0.05). The positive reaction rate to whole body of American cock-roach (AC) was significantly higher in the patient group than control group (p<0.05), but the positive rate to whole body of GC was high, but not significantly high in the patient group (p = 0.053). There were significant differences in positive patch test reactions to either Ext or As is between patient group and control group (p<0.05). The positive rate to As is was significantly higher than to Ext in either lesional skin or non-lesional skin in patient group (p<0.05). But there were no considerable differences in positive reactions to either Ext or As is between 3 different methods (standard, scratch, DMSO mix) in both lesional and non-lesional areas (p>0.05). There was no significant relationship between the positive reactions to patch test and prick test to Ext and As is antigen. The APT results showed no significant concordances with skin prick test and RAST for cockroach antigens.

APT seems to be a different dimension of atopic skin inflammation and may pro-vide further diagnostic information in addition to a patient's history, skin prick test, and RAST results.