Patch test characteristics of patients referred for suspected contact allergy of the feet-retrospective 10-year cross-sectional study of the IVDK data

Abstract

Background. The warm und humid environment, friction and occlusion within shoes make the feet to a favorable body site to acquire allergic contact dermatitis. Objectives. To evaluate and compare patch test results in patients with suspected contact allergy of the feet with the results in those with concomitant involvement of the feet/legs, feet/hands, and all others tested (excluding secondary involvement of the feet in `others'), with regard to specific patterns of clinical data and patch test results. Methods. For the present cross-sectional study, data were collected by the 59 participating centres of the Information Network of Departments of Dermatology in Germany, Austria, and Switzerland, including 102 209 patients patch-tested between January 2001 and December 2010. Results. Allergens that were significantly over-represented in the tested 2671 foot patients included potassium dichromate, colophonium, and p-tert-butylphenolformaldehyde resin. Among materials brought in by the patients, shoe pieces (27.5%), topical medications/pharmaceutical products (24.4%) and cosmetics (16.8%) played a major role. The final diagnoses of vesicular and hyperkeratotic dermatitis, as well as psoriasis, were significantly more common among foot patients. Conclusions. Chromium compounds and adhesives were the most common causes of allergic contact dermatitis among our foot patients. Psoriasis should be considered, particularly when the hands are concomitantly affected.