SAN FRANCISCO – What do you consider when one of your atopic pediatric patients has recalcitrant dermatitis? Or a new-onset dermatitis that lasts longer than 2 months? It might be time to expand your differential diagnosis to consider contact dermatitis, Dr. Sharon Jacob said.

There is a high prevalence of allergic contact dermatitis in moderate to severe atopic patients. Also, think systemic allergic contact dermatitis in highly sensitized children. Although more commonly reported in adults, systemic allergies can affect pediatric patients, Dr. Jacob said at a meeting sponsored by Skin Disease Education Foundation (SDEF).

Exposure to nickel, cobalt, fragrances, formaldehyde and balsam of Peru – including from dietary sources – can trigger a systemic reaction. System allergy "should be considered in children with a positive patch test who fail to improve with skin contact avoidance," she said.

A diet devoid of the suspected trigger(s) for 6 weeks or more can make a difference for some recalcitrant children, said Dr. Jacob, an assistant clinical professor of medicine (dermatology) and pediatrics at the University of California, San Diego, and at Rady Children’s Hospital. Such an avoidance diet improved the outcome for eight pediatric patients with systemic allergies, according to a recent report from Dr. Jacob and Dr. C. Matiz (Pediatr. Dermatol. 2010 Aug 27 [doi: 10.1111/j.1525-1470.2010.01130.x]).

An avoidance diet is particularly challenging for children with allergy to balsam of Peru. This allergen is found in many foods, including tomatoes, citrus, and certain spices, according to a study in adults (J. Am. Acad. Dermatol. 2001;45:377-81).

"The food we have the most problem with is ketchup. Ketchup and pizza are the bane of my existence," Dr. Jacob said. Keep the diet simple if possible and encourage adherence with incentives for the child, such as a points and rewards system, she added.

Be careful how you counsel these children, Dr. Jacob said. "Start off with the fact they cannot have asparagus – 'Yes!' – or spinach 'Yay!' Then mention ketchup, chocolate, and soda, and you become the evil contact derm pediatrician."

Sometimes an affected anatomic site is an important clinical clue. For example, Dr. Jacob described a 10-month-old child with generalized dermatitis who also presented with specific perioral dermatitis. "When we see this we think balsam of Peru." Involvement of the eyelids is another clinical clue.

Another interesting case Dr. Jacob presented was a toddler with a fragrance contact allergy that triggered a systemic reaction. Initially, however, she had to figure out how a toddler could have an allergy to fragrance. She discovered that the toddler became sensitized from "connubial contact" – or a physical transfer – of fragrance from the mother’s neck. Following this discovery, the child was doing well until a flare associated with vanilla teething wafers. "It’s amazing how much vanilla is everywhere."

When an allergen or chemical is transferred by the patient to another site on their body, it is called "ectopic dermatitis." Dr. Jacob cited the case of a 3-year-old whose older sister lacquered her fingernails, for example. The younger child scratched other areas and reacted to the tosylamide formaldehyde resin on her nails.

If you have a child whose controlled condition suddenly worsens in their atopic areas, consider these potential culprits: lanolin, neomycin, and bacitracin, Dr. Jacob said.

Lanolin is derived from the sebaceous gland in sheep. Although removed from most wool clothing during processing, it remains in cashmere clothing to keep it soft. "Lanolin is a top offender in children – because it is used in emollients," Dr. Jacob said.

Also assess these patients for exposure to plants in the Compositae family – including feverfew and chamomile. Keep in mind some components may be found in preparations you prescribe for their atopic dermatitis, such as bisabolol, an alcohol compound derived from chamomile and found in Aquaphor ointment (Beiersdorf Inc.) and sometimes prescribed for atopic dermatitis in children (Pediatr. Dermatol. 2010;27:103-4)

Also watch out for emulsifiers used in diaper creams and topical steroids, including sorbitan sesquioleate. Reports of contact dermatitis to this sorbitan are increasing (Dermatitis. 2008:19:339-41).

Dr. Jacob noted that patch testing of children for contact allergies is "off-label" – not approved by the Food and Drug Administration.

A meeting attendee asked Dr. Jacob about the youngest age patient that she will patch test. "I have patch tested a patient as young as 10 months old. But I generally do not patch test children under 5 years old unless absolutely indicated," she replied. She first tries "preemptive avoidance" of suspected allergens in these young children before patch testing.

SDEF and this news organization are owned by Elsevier. Dr. Jacob is a speaker for Coria Laboratories, Astellas Pharma Inc., and Shire. She is also an independent investigator for Allerderm, maker of the T.R.U.E. test.

When to Consider Allergic Contact Dermatitis in an Atopic Child