Allergic contact dermatitis in patients with otitis externa

Background and Objective. The Information Network of Departments of Dermato logy (IVDK) centrally collects patch tests results in cooperation with the German Contact Dermatitis Research Group (DKG). Data of patients, who under went patch testing to evaluate otitis externa were analyzed. Patients/Methods. Data of 145 patients that had been recorded between 1992 and 1997 were evaluated. The evaluation included data yielded by standardiz ed patch testing as well as by patch testing of products that the patients had used. Results. Allergic contact dermatitis was diagnosed in one third of patients suffering from otitis externa. Topical drugs were shown to be the most imp ortant allergens. In comparison to the entire IVDK collective, the populati on-adjusted frequency of sensitization (PAFS) of neomycin sulfate was highe r in the study population whereas that of nickel sulfate was lower. That sh ows that in a very specific topographic area, different allergens may be of clinical significance. Conclusions. Whereas nickel sulfate represents an important allergen in the contact dermatitis of the external ear, topical therapeutical agents, espe cially neomycin sulfate and, as evaluation of the patch tests of the patien t's own products revealed, probably polymyxin B are the dominating allergen s in otitis externa.