AEROALLERGEN PATCH TESTING FOR PATIENTS PRESENTING TO CONTACT-DERMATITIS CLINICS

Background: The role of aeroallergens in the production of allergic co ntact dermatitis or ''allergic contact dermatitis-like'' atopic dermat itis is controversial. Although techniques and allergens lack standard ization, most studies find positive patch test results in 30% to 40% o f patients with atopic dermatitis. Objective: Our purpose was to deter mine the prevalence and clinical significance of positive aeroallergen patch tests in patients undergoing standard patch testing for suspect ed ''nonaeroallergen'' allergic contact dermatitis. Methods: One hundr ed three consecutive patients referred to three university patch test clinics for patch testing were also patch tested with six common aeroa llergens in glycerine-dust, mold, cat epithelium, tree, grass, and wee d-as well as with a glycerine control. Patches were removed at 48 hour s. Readings were performed at this time and at 3 to 7 days after initi al application. Results: As determined by history, these 103 patients included 16 patients with both atopic dermatitis and mucosal atopy, 10 patients with atopic dermatitis only, 22 patients with mucosal atopy only, and 55 patients with neither atopic dermatitis nor mucosal atopy . Allergic reactions were seen to one aeroallergen in five patients (t hree with atopic dermatitis and mucosal allergy, and two with no histo ry of atopy). The prevalence (3 of 16 [18.8%]) of reactions in patient s with both atopic dermatitis and mucosal allergy was significantly gr eater than the prevalence (2 of 87 [2.3%]) in patients with only one o r neither of these two atopic disorders (p=0.02). None of these aeroal lergen contact hypersensitivities were deemed significant in the patie nts' current dermatitis. However, reactions were of past relevance in two of the three patients with atopic dermatitis and mucosal allergy. Conclusion: In this referral group, none of the six common aeroallerge ns tested was relevant in the origin of suspected ''nonaeroallergen'' allergic contact dermatitis. This study suggests that aeroallergen pat ch testing is of little use in the evaluation of patients referred for routine patch testing for suspected ''nonaeroallergen'' allergic cont act dermatitis. Similar but larger studies inclusive of the assessment of relevance, as well as masked controlled clinical trials assessing the effect of aeroallergen exposure and avoidance, are needed to evalu ate this issue more fully.