Patch testing and aeroallergen intradermal testing in facial dermatitis

The rôle of contact allergens and aeroallergens in facial dermatitis (FD) was studied. 114 cases of FD were divided into 3 groups. Group 1 comprised 47 cases of facial cosmetic dermatitis (FCD), in which all patients had a history of dermatitis related to cosmetics clinically; group 2 comprised 15 cases of seasonal facial dermatitis (SFD); Group 3 comprised 52 cases of other FD (OFD) that could not be categorized as FCD or SFD. Reactions to contact allergens and aeroallergens were detected using patch testing and intradermal testing, respectively, with non-facial eczematous skin disease patients serving as controls. The positivity rate for each allergen between different groups was compared by the chi2-test. The results show that the positivity rate for fragrance mix in FCD is much higher than in non-FCD (27.7% versus 6.7% in SFD, 7.6% in OFD and 6% in eczema patients, p<0.05). No significant difference was detected for other common allergens, such as PPD, rubber mix, nickel sulfate, and colophonium (p>0.05 for all). These results suggest that fragrance mix contains the main contact allergens in FCD. Patch testing with patients' own products also yields high numbers of relevant results in FCD and OFD. No relevant patch test results were found in SFD, indicating that contact allergy may not be relevant to SFD. No significant difference was observed between intradermal skin reactions to aeroallergens, including pollens and moulds, in SFD, OFD, FCD and controls. These results suggest that Type I reactions to aeroallergens may not be relevant in FD. The rôle of aeroallergens in FD needs to be studied further.