Characterization of Pediatric Patch Testing: A Retrospective Review, 2020-2023.

Background: Recent evidence shows similar rates of allergic contact Dermatitis® (ACD) among children and adults despite children accounting for less than 10% of patch testing subjects. With a need for in-depth analyses of pediatric ACD, we herein characterize a pediatric cohort at a large North American patch testing center. Methods: A retrospective chart review was conducted for 135 patients ages 1-17 years who underwent patch testing from July 2020 from August 2023. Data were stratified by age 1-5, 6-11, and 12-17 years. Significance-Prevalence Index Numbers (SPIN) were calculated. Results: A total of 86% were sensitized, 40% had a relevant reaction, and positivity rates were equal between males and females. Top allergens by SPIN differed with age, but overall were linalool hydroperoxides (SPIN = 11.01), propylene glycol (10.30), limonene hydroperoxides (10.27), fragrance mix I (5.62), and lanolin (4.90). In total, 14% of the top allergens were not represented on the North American Contact Dermatitis® Group standard series. Of those tested to personal products, 45% had positive reactions and 72% of which were relevant. Conclusions: Emulsifiers and fragrances were the most relevant allergen categories, with the impact of emulsifiers not previously reported. ACD may affect males and females equally in this population. Supplemental allergens and personal products tested "as-is" contribute to conclusive pediatric patch testing.