[Contact allergies in patients with eczema of the external ear canal. Results of the Information Network of Dermatological Clinics and the German Contact Allergy Group]

Abstract

Background and objective: The Information Network of Departments of Dermatology (IVDK) centrally collects patch tests results in cooperation with the German Contact Dermatitis Research Group (DKG). Data of patients, who underwent 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 standardized 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 important allergens. In comparison to the entire IVDK collective, the population-adjusted frequency of sensitization (PAFS) of neomycin sulfate was higher in the study population whereas that of nickel sulfate was lower. That shows 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, especially neomycin sulfate and, as evaluation of the patch tests of the patient's own products revealed, probably polymyxin B are the dominating allergens in otitis externa.