MAUI, HAWAII — The first two multicenter studies of patch testing conducted in American children have established that the same ubiquitous allergens responsible for most allergic contact dermatitis in U.S. adults are similarly prevalent and clinically relevant in the pediatric population.
The two studies demonstrated that comprehensive patch testing in children using the same allergen concentrations as in adults is both safe and efficacious, Dr. Sharon E. Jacob said at the annual Hawaii dermatology seminar sponsored by Skin Disease Education Foundation.
One study was conducted by the North American Contact Dermatitis Group (NACDG). It involved 391 children—including 144 younger than 13 years old—and 9,670 adults with recalcitrant dermatitis who were patch tested using all or part of the 65-antigen NACDG screening series. Fifty-one percent of the children and 54% of adults proved to have at least one positive patch test deemed clinically relevant, meaning that the offending allergen caused the patient's symptoms (Arch. Dermatol. 2008;144:1329–36).
Dr. Jacob was the lead investigator in the other study, in which 65 children (aged 1–18 years) with recalcitrant dermatitis were patch tested. Of the children, 50 (77%) had one or more positive patch tests considered clinically relevant (Pediatr. Dermatol. 2008;25:520–7).
Both studies were retrospective and involved referral populations.
Many of the top causes of pediatric ACD internationally proved to be the same allergens that came to the fore in the two U.S. studies, noted Dr. Jacob, a pediatric dermatologist at the University of California, San Diego.
For example, nickel was the No. 1 cause of pediatric ACD internationally. It was also the top cause in Dr. Jacob's study, where it accounted for 18% of cases, and in the NACDG study, in which 26% of children were found to have ACD due to nickel. Thimerosal was No. 4 internationally, No. 2 in Dr. Jacob's study, and No. 3 in the NACDG study. Balsam of Peru (Myroxylon pereirae) was No. 5 abroad, No. 3 in Dr. Jacob's study, and No. 7 in the NACDG series.
Dr. Jacob has synthesized the key findings of the two U.S. studies to compile a list of the top pediatric ACD allergens in the United States. (See Box.)
She urged her colleagues to consider patch testing all children with recalcitrant dermatitis that clears only with superpotent topical or oral corticosteroids. Dermatitis on the hands or eyelids is particularly suggestive of ACD. The testing often yields a big clinical payoff.
“Children with clinically relevant patch test results show significant improvement with allergen avoidance,” Dr. Jacob said.
Dr. Jacob disclosed that she is on the speakers bureaus for Astellas Pharma, Inc. and Coria Laboratories, and has received research grants from Allerderm.
SDEF and this news organization are owned by Elsevier.
Consider testing all children with dermatitis that clears only with superpotent topical or oral corticosteroids. DR. JACOB
Top Contact Allergens in U.S. Children
▸ Nickel and cobalt. These two allergens are listed jointly because they're mined together in iron ore and often cosensitize. Nickel, named the American Contact Dermatitis Society's “Allergen of the Year” for 2008, will be the target of a planned major U.S. initiative to reduce environmental nickel release.
Nickel is found in many metal objects, including jeans snaps, zippers and orthodontic braces. Chocolate is the top food source.
▸ Neomycin. The No. 2 contact allergen in U.S. adults for the last 30 years, this antibiotic is also a cause of ACD in kids.
▸ Balsam of Peru and fragrance mix. This combination contact allergen is widely utilized to impart flavors in food products as well as for scent.
▸ Formaldehyde and quaternium-15. A common preservative, formaldehyde is a major cause of systemic allergic reactions.
▸ Potassium dichromate. Cement, leather, and watch straps are often implicated in pediatric ACD.
▸ Colophony. This allergen often is present in adhesives and cosmetics.
▸ Lanolin. This alcohol extraction of sheep sebum is used as an emulsifier and emollient. It is found in cosmetics, creams, and leather.
▸ Carbamates. Commonly causing ACD, carbamates are used as accelerators in rubber.
▸ Para-phenylenediamine. Watch out for this in temporary tattoos.
▸ Sorbitan sesquioleate. An emulsifier increasingly used to enhance penetration of topical medications, including corticosteroids. It's also present in many diaper balms.
▸ Disperse dyes. These are found in clothing and diapers.
Source: Dr. Jacob