Patch testing is a useful investigation in children with eczema

Background. Allergic contact dermatitis in children is less recognized than in adults. However, recently, allergic contact dermatitis has started to attract more interest as a cause of or contributor to eczema in children, and patch testing has been gaining in recognition as a useful diagnostic tool in this group. Objectives. The aim of this analysis was to investigate the results of patch testing of selected children with eczema of various types (mostly atopic dermatitis) attending the Sheffield Children's Hospital, and to assess potential allergens that might elicit allergic contact dermatitis. Patients and methods. We analysed retrospectively the patch test results in 110 children aged between 2 and 18 years, referred to a contact dermatitis clinic between April 2002 and December 2008. We looked at the percentages of relevant positive reactions in boys and girls, by age groups, and recorded the outcome of treatment following patch testing. Results. One or more positive allergic reactions of current or past relevance was found in 48/110 children (44%; 29 females and 19 males). There were 94 allergy-positive patch test reactions in 110 patients: 81 had a reaction of current or past relevance, 12 had a reaction of unknown relevance, and 1 had reaction that was a cross-reaction. The commonest allergens with present or past relevance were medicaments, plant allergens, house dust mite, nickel, Amerchol (R) L101 (a lanolin derivative), and 2-bromo-2-nitropropane-1,3-diol. However, finding a positive allergen was not associated with a better clinical outcome. Conclusions. We have shown that patch testing can identify relevant allergens in 44% of children with eczema. The commonest relevant allergens were medicament allergens, plant allergens, house dust mite, nickel, Amerchol (R) L101, and 2-bromo-2-nitropropane-1,3-diol. Patch testing can be performed in children as young as 2 years with the proper preparation.