Contact sensitization in very young children Anna Belloni Fortina, MD, a Ilaria Romano, MD, PhD, a Andrea Peserico, MD, b and Lawrence F. Eichenfield, MD c Padua, Italy, and San Diego, California Background: Allergic contact dermatitis is an increasingly recognized clinical problem in children. Objective: The aim of our study was to evaluate contact sensitization in patients younger than 3 years of age with suspected contact dermatitis. Methods: During a 6-year period (2002-2008), 321 children underwent routine patch testing with a screening pediatric standard series of 30 allergens. Results: Two hundred children (62.3%; 102 girls and 98 boys aged 3-36 months [mean age 27 1 5.6 months]) developed at least one positive reaction. The most frequent reactions were to nickel sulfate (26.8%), followed by potassium dichromate (9%), cocamidopropylbetaine (7.2%), cobalt chloride (6.2%), neomycin sulfate (5%), and methylchloroisothiazolinone/methylisothiazolinone (4.4%). The prevalence of contact sensitization was similar in children with (61.3%) and without (63%) atopic dermatitis. Limitations: The prevalence of contact sensitization in children younger than 3 years of age was not compared with the prevalence in older children. Conclusion: A high prevalence of contact sensitization was found in preschool children, even younger than 3 years of age. Patch testing should be considered in this age group when persistent dermatitis does not respond to conventional treatment. ( J Am Acad Dermatol 2011;65:772-9.) Key words: allergic contact dermatitis; atopic dermatitis; children; cobalt chloride; cocamidopropylbetaine; contact sensitization; methylchloroisothiazolinone/methylisothiazolinone; neomycin sulfate; nickel sulfate, patch testing; potassium dichromate. INTRODUCTION Allergic contact dermatitis (ACD) in children is an increasingly recognized clinical problem. 1,2 In the past, ACD was considered uncommon in childhood because of a presumed low exposure to contact allergens and less susceptible immune system. 1 Recent studies have documented that contact sensi- tization in children is more frequent than was previ- ously thought. 3-8 While there is a fair amount of information about older children, data are scarce on the prevalence of contact sensitization in children under 3 years of age. The aim of our study was to evaluate contact sensi- tization in a cohort of 321 consecutive children younger than 3 years of age with suspected ACD who were patch tested at the Dermatology Unit of the Department of Pediatrics at the University of Padova from 2002 to 2008. MATERIAL AND METHODS Three hundred twenty-one consecutive children (177 females and 144 males) under 3 years of age Abbreviations used: ACD: allergic contact dermatitis D2: day 2 (48 hours after patch test application) D4: day 4 (96 hours after patch test application) MCI/MI: methylchloroisothiazolinone/ methylisothiazolinone PPD: para-phenylenediamine From the Dermatology Unit, Department of Pediatrics, a and the Dermatology Unit, b University of Padova; and Pediatric and Adolescent Dermatology, Rady Children’s Hospital, University of California, San Diego. c Funding sources: none Conflicts of interest: None declared. Accepted for publication July 14, 2010. Reprint requests: Anna Belloni Fortina, Dermatology Unit, Department of Pediatrics, University of Padova, via Giustiniani 3, 35128 Padova (Italy). E-mail: belloni@pediatria.unipd.it. Published online May 26, 2011. 0190-9622/$36.00 ª 2010 by the American Academy of Dermatology, Inc. doi:10.1016/j.jaad.2010.07.030 772