Dr. Kari L. Martin
“Time needs to be allocated for a patch test consultation, placement, removal, and reading,” she said at the virtual annual meeting of the Society for Pediatric Dermatology. “You will need more time in the day that you’re reading the patch test for patient education. However, your staff will need more time on the front end of the patch test process for application. Also, if they are customizing patch tests, they’ll need time to make the patch tests along with access to a refrigerator and plenty of counter space.”
Other factors to consider are the site of service, your payer mix, and if you need to complete prior authorizations for patch testing.
Dr. Martin, associate professor of dermatology and child health at the University of Missouri–Columbia, said that the diagnosis of allergic contact dermatitis (ACD) crosses her mind when she sees a patient with new dermatitis, especially in an older child; if the dermatitis is patterned or regional; if there’s exacerbation of an underlying, previously stable skin disease; or if it’s a pattern known to be associated with systemic contact dermatitis. “In fact, 13%-25% of healthy, asymptomatic kids have allergen sensitization,” she said. “If you take that a step further and look at kids who are suspected of having allergic contact dermatitis, 25%-96% have allergen sensitization. Still, that doesn’t mean that those tests are relevant to the dermatitis that’s going on. If you take kids who are referred to tertiary centers for patch testing, about half will have relevant patch test results.”
Pediatric ACD differs from adult ACD in three ways, Dr. Martin said. First, children have a different clinical morphology and distribution on presentation, compared with adults. “In adults, the most common clinical presentation is hand dermatitis, while kids more often present with a scattered generalized morphology of dermatitis,” she said. “This occurs in about one-third of children with ACD. Their patterns of allergen exposure are also different. For the most part, adults are in control of their own environments and what is placed on their skin, whereas kids are not. When thinking about what you might need to patch test a child to if you’re considering ACD, it’s important to think about not only what the parent or caregiver puts directly on the child’s skin but also any connubial or consort allergen exposure – the most common ones coming from the caregivers themselves, such as fragrance or hair dyes that are transferred to a young child.”
The third factor that differs between pediatric and adult ACD is the allergen source. Dr. Martin noted that children and adults use different personal care products, wear different types of clothing, and spend different amounts of time in play versus work. “Children have many more hobbies in general that are unfortunately lost as many of us age,” she said. That means “thinking through the child’s entire day and how the seasons differ for them, such as what sports they’re in and what protective equipment may be involved with where their dermatitis is, or what musical instruments they play.”
Applying the T.R.U.E. patch test panel or a customized patch test panel to young children poses certain challenges, considering their limited body surface area and propensity to squirm. Dr. Martin often employs distraction techniques when placing patches on young patients, including the use of bubbles, music, movies, and games. “The goal is always to get as much of the patches on the back or the flanks as possible,” she said. “If you need additional space you can use the upper outer arms, the abdomen, or the anterior lateral thighs. Another thing to consider is how to set up your week for pediatric patch testing. There’s a standardized process for adults where we place the patches on day 0, read them on day 2, with removal of the patches at that time, and then perform a delayed read between day 4-7.”
The process is similar for postpubescent children, despite the lack of clear guidelines in the medical literature. “There is much controversy and different practices between different pediatric patch test centers,” Dr. Martin said. “There is more consensus between the older kids and the prepubescent group ages 6-12. Most clinicians will still do a similar placement on day 0 with removal and initial read on day 2, with a delayed read on day 4-7. However, some groups will remove patches at 24 hours, especially in those with atopic dermatitis (AD) or a generalized dermatitis, to reduce irritant reactions. Others will also use half-strength concentrations of allergens.”
The most controversy lies with children younger than 6 years, she said. For those aged 3-6 years, who do not have AD, most practices use a standardized pediatric tray with a 24- to 48-hour contact time. However, patch testing can be “very challenging” for children who are under 3 years of age, and children with AD who are under 6 years, “so there needs to be a very high degree of suspicion for ACD and very careful selection of the allergens and contact time that is used in those particular cases,” she noted.
The most common allergens in children are nickel, fragrance mix I, cobalt, balsam of Peru, neomycin, and bacitracin, which largely match the common allergens seen in adults. However, allergens more common in children, compared with adults, include gold, propylene glycol, 2-Bromo-2-nitropropane-1,3-diol, and cocamidopropyl betaine. “If the child presents with a regional dermatitis or a patterned dermatitis, sometimes you can hone in on your suspected allergens and only test for a few,” Dr. Martin said. “In a child with eyelid dermatitis, you’re going to worry more about cocamidopropyl betaine in their shampoos and cleansers. Also, a metal allergen could be transferred from their hands from toys or coins, specifically nickel and cobalt. They also may have different sports gear such as goggles that may be affecting their eyelid dermatitis, which you would not necessarily see in an adult.”
Periorificial contact dermatitis can also differ in presentation between children and adults. “In kids, think about musical instruments, flavored lip balms, gum, and pacifiers,” she said. “For ACD on the buttocks and posterior thighs, think about toilet seat allergens, especially those in the potty training ages, and the nickel bolts on school chairs.”
In 2018, Dr. Martin and her colleagues on the Pediatric Contact Dermatitis Workgroup published a pediatric baseline patch test series as a way to expand on the T.R.U.E. test (Dermatitis. 2018;29[4]:206-12). “It’s nice to have this panel available as a baseline screening tool when you’re unsure of possible triggers of the dermatitis but you still have high suspicion of allergic dermatitis,” Dr. Martin said. “This also is helpful for patients who present with generalized dermatitis. It’s still not perfect. We are collecting prospective data to fine-tune this baseline series.”
She reported having no financial disclosures.