PracticeUpdate: Dermatology & Rheumatology

SPD 2016 15

Allergic contact dermatitis in the paediatric population By Sarah Chamlin MD E rin Warshaw MD, MS from the University of Min- nesota reviewed paediatric allergic contact dermatitis (Warshaw E, Contact Dermatitis in Children. Paper because children are exposed to aluminum as a vaccine excipient, and an irritant reaction to this may lead to difficulty with test interpretation. – – Carefully interpret doubtful reactions, as children may have a higher rate of irritant reactions.

presented at: 42nd Annual Society for Pediatric Dermatol- ogy Meeting; July 14–17, 2016; Minneapolis, MN) and, as part of her discussion, provided key points of how patch testing differs in children. • In the largest and most recent 2014 study of allergic contact dermatitis in children, 62% of children had positive patch tests (PPT), with 58% relevant ( Dermatitis 2014;25:345-355). These numbers are lower than those published for adults, and the presence of atopy in the children did not make a difference in the number of positive reactions. • The top seven allergens reported for adults and children are nickel sulfate, cobalt chloride, neomycin sulfate, Myroxylon pereirae (balsam of Peru) lanolin, fragrance mix, and bacitracin. • Notably 23% of children reacted to a supplemental allergen not included in the common patch tests, and 13% reacted only to a supplemental allergen, a non- standard allergen. A hypothetical TRUE Test sensitivity can be estimated to detect relevant PPTs in only 71% of children. Therefore, a TRUE Test is an acceptable screening test, but supplemental allergens may be needed, such as those in cosmetics, rubber, clothing, and preservatives. • Important allergens that are not on a TRUE Test include methylisothiazolinone (MI), propolis, decyl glucoside, surfactants, tocopherol, oxybenzone, and botanicals. • How is the approach to patch testing different in children? – – Plastic IQ chambers are used in children <10 years old. Aluminum Finn chambers are avoided by Dr Warshaw

– – Patch testing can be beneficial in children withAD, but expectations should be reviewed with parents before testing. The patch testing goal in children with AD is to return the dermatitis to its baseline severity. Parents may also need to be reminded that patch testing is not for food allergies. • CAMP lists (of real and doubtful allergens) are available through the Contact Dermatitis Society and can be obtained in academic centres through a society member with a password. All real and doubtful allergen avoidance is suggested for 3 months followed by stepwise weekly addition of doubtful allergens. • A few more pearls: – – MI, which replaced formaldehyde as a common preservative, is a very common allergen in adults and children and is causing an epidemic in the contact dermatitis world. It was voted the 2013 allergen of the year, and “in-press” data will report it moving to the “Top 5” allergen list. Of note, the TRUE test includes methylchloroisothiazolinone (MCI) but not MI. – – Decyl glucoside is another important and emerging allergen. This is in fragrance-free shampoos and soaps and is used as a sunscreen stabiliser in some products. – – Polymyxin cross-reacts with bacitracin. Many parents frequently use topical antibiotics with no awareness of their allergenicity. – – Cobalt, found in leather, will be the 2016 allergen of the year.

studied, 2005 to 2014. This is another wake- up call to avoid the overuse of clindamycin. Blood cultures are not useful in the evaluation of children with uncomplicated superficial skin and soft tissue infections. Trenchs V, Hernandez- Bou S, Bianchi C, et al. Pediatr Infect Dis J 2015;34:924-927. • Obtaining blood cultures in immuno- competent children with uncomplicated superficial skin and soft tissue infections (impetigo, abscesses, and cellulitis) is not useful and is not suggested by the authors of this Spanish study.

2015;372:803-813), counselling for infant food introduction is most often left to the primary care provider or an allergist. Changing susceptibility of Staphylococcus aureus in a US pediatric population. Sutter DE, Milburn E, Chukwuma U, et al. Pediatrics 2016;137:e20153099. • There are been a declining number ofMRSA infections in adults, and this study reports decreasing rates of MRSA in children as well. Notably, susceptibility to oxacillin increased and resistance to clindamycin significantly decreased over the time period

Maternal vitamin D levels are inversely related to allergic sensitization and atopic diseases in early childhood. Chiu CY, Huang SY, Peng YC, et al. Pediatr Allergy Immunol 2015;26:337-343. • Maternal vitamin D levels are inversely related to allergic sensitisation and atopic diseases in early childhood. Mothers with deficient vitamin D in this 4-year study had infants with a higher prevalence of allergen sensitisation (food and dust mite) before the age of 2 years, and higher vitamin D levels were associated with a lower risk in offspring for asthma and eczema.

DECEMBER 2016