Allergic contact dermatitis in 191 consecutively patch tested children

Abstract

We studied a population of children attending for patch testing in south Wales to determine the prevalence rates of allergic contact dermatitis (ACD), and to compare this with previous studies of both children and adults. We also aimed to identify allergens particularly relevant to childhood ACD. The patch-test databases from 1993 to 2003 in 2 centres (Swansea and Cardiff – total population 677 500) were searched for all children, 16 years and under, with a positive patch test to the European standard series. The frequency of ACD and the spectrum of allergens was recorded. We identified 191 consecutively patch-tested children. 41% had a positive result to 1 or more allergens. Of these, 51.7% were documented to be of current relevance. 19.6% had multiple positive patch tests. The most common allergen was nickel (13%), followed by fragrance (9%), thiuram (9%), cobalt (8%), para-phenylenediamine (PPD) (6%), tixocortol pivalate (5%) and Myroxylon pereirae resin (5%). A review of 17 studies of ACD in children under 16 years (sample size 53–1023 patients per study) (1) showed a positive patch-test frequency of 14.5–70.7%. Current relevance was found in 56.4–93.3% of these, and multiple reactions were found in 3.2–54.4% of cases. Our results show similar prevalence rates of positive single and multiple patch-test reactions, but a lower percentage with current relevance. Nickel, cobalt, chromate, fragrance and formaldehyde produced the highest number of reactions with doubtful or no relevance, possibly due to an irritant effect or a cross-reaction. The order of prevalence of ACD to individual allergens was largely comparable with a general adult population (2), with nickel, fragrance and Myroxylon pereirae resin having the highest rates. However, thiuram and PPD allergy was proportionately higher in children. The frequency of PPD allergy showed an increased rate of 6.3% compared with most previous studies. 3 cases of PPD allergy were in trainee hairdressers with allergies to other work-related chemicals (ammonium persulphate in 2 and glyceryl thioglycolate in 1). 2 children had reacted to black henna tattoos, an increasingly common presentation in children. The sources of these allergens were often related to sports and hobbies. Examples of these include thiuram or mercapto allergy related to cricket bats, badminton rackets golf clubs and trainers. 1 case of cobalt allergy was attributed to the wearing of a blue leather hockey glove, and 1 case of colophonium allergy was seen in a violinist. 1 teenager developed an allergy to benzoyl peroxide in her acne treatment. Our study has shown that, despite the frequency of ACD in children being comparable with previous studies, the spectrum and frequency of individual allergens has changed in recent years. PPD and thiuram allergy have a higher frequency in our study compared with adult populations. The sources of these allergens are often different from adults, and we have highlighted the need to consider this even more in our history-taking, when faced with the younger patient in the patch test clinic.