Prevalence of contact allergy in children suffering from atopic dermatitis, seborrhoeic dermatitis and in healthy controls

Introduction: Atopic dermatitis is one of the most common skin disorders in children. There is only scarce literature data on the prevalence of contact allergy in children with atopic dermatitis. Objectives: To assess the prevalence of contact allergy among children with atopic dermatitis, seborrhoeic dermatitis and in a population of healthy children. Material and methods: Patch tests were performed in 104 children aged 1-20 years treated for atopic dermatitis in the Department of Dermatology, University of Medical Sciences, Poznan, and also in 2 control groups: 15 subjects with seborrhoeic dermatitis (15-20 years) and 36 healthy children (1-20 years). Results: In children with atopic dermatitis, contact allergy was observed in 47/104 patients (45.2%). With regards to the 3 age subgroups, positive patch test results were detected in 30/43 in children aged 1-5 years (69.8%), 13/36 in children aged 6-14 years (36.1%) and in 4/25 adolescents 15-20 years of age (16%). The highest proportion of positive patch tests was detected in the youngest subgroup of healthy children. Comparative analysis revealed type IV hypersensitivity statistically significantly more frequent in children with atopic dermatitis than in the 2 control groups. Conclusions: The statistically significant positive results in the highest proportion of patch tests in the youngest age subpopulation of children with atopic dermatitis, and detection of contact allergy most commonly in the youngest subgroup of healthy children, may suggest nonspecifically positive results associated with the immaturity of the epidermal barrier during the first years of life. Concentrations of contact allergens included in current pediatric sets of patch tests seems to be too high and should be verified.