ORLANDO – Do you have ? Consider patch testing to assess whether they have allergic contact dermatitis.
Jeff Craven/MDedge News
Dr. Jonathan H. Zippin
“Of the patients who are sent to me by local pediatric dermatologists, 50% of them are positive” for allergens, said Jonathan H. Zippin, MD, PhD, director of the contact, occupational, and photodermatitis service at Cornell University, New York.
Speaking at the ODAC Dermatology, Aesthetic, and Surgical Conference, Dr. Zippin noted the prevalence of allergen sensitization is between 13% and 25% among children who are asymptomatic, while the prevalence of sensitization to at least one allergen among children with suspected allergic contact dermatitis (ACD) is between 25% and 96%. In 2014, a study from the National American Contact Dermatitis Group (NACDG) showed that of 883 children who were patch tested, 56.7% had at least one relevant positive patch test (RPPT) result.
“The take-home message here is that pediatric contact dermatitis is common, much more common than a lot of people realize,” Dr. Zippin said.
He described three common scenarios to keep in mind: a worsening rash, a new rash, and failure of a rash to improve after the patient avoids all of his or her positive allergens.
When a rash worsens, patch testing is likely to offer answers. In an analysis of 1,142 patients with suspected ACD aged 18 years or younger (mean age, 10.5 years; 64% female) in the Pediatric Contact Dermatitis Registry study database, 65% had at least one positive patch test, and 48% had at least 1 RPPT (Dermatitis 2016; 27[5] 293-302).
But not all patch testing is the same: The study also found that 24% of the RPPT cases would have been missed if assessed with the T.R.U.E. TEST compared with extended patch testing. If a T.R.U.E. TEST fails to explain generalized atopic dermatitis, the patient should be sent for more comprehensive testing where available, Dr. Zippin advised.
Pediatric patients also have unique allergens clinicians should consider. In the same study, children had a number of allergens similar to those of adults as reported in previous studies, such as nickel, cobalt, and neomycin. However, propylene glycol and cocamidopropyl betaine were allergens identified as unique to the pediatric population.
Another study looking at the same group of patients found that compared with children who did not have AD, children with AD had 7.4 times higher odds of having an RPPT to cocamidopropyl betaine, 7.6 times higher odds of having an RPPT to parthenolide, 5.3 times higher odds of having an RPPT to tixocortol pivalate, 4.2 times higher odds of having an RPPT to wool alcohols, and 4 times higher odds of having an RPPT to lanolin (JAMA Dermatology 2017;153[8]:765-70).
All of these are components of topical medicaments used to treat AD, “either components of emollients that we recommend, or components of steroids that we recommend,” Dr. Zippin pointed out.
One of these allergens could be the culprit when a child develops a new rash but there are no new apparent changes in products, exposures, and activities. Lanolin, also called wool grease, is used in many skin care products, for example. Dr. Zippin described the case of a 6-year-old girl with a history of AD, who presented with a new rash on her scalp and behind her ears, not explained by any obvious changes to products, exposures, or activities. Subsequent patch testing determined that the rash was caused by baby shampoo, which contained cocamidopropyl betaine, which is used in hypoallergenic products. The rash resolved after a different shampoo was used.
“Sometimes, we really have to be thinking when the rash is getting worse, is there something they’re being exposed to that might be an allergen?” Dr. Zippin said.
In patients who have avoided all their positive allergens but a rash has not improved, clinicians should consider systemic contact dermatitis (SCD). Patients can develop SCD through different types of exposures, including transepidermal, transmucosal, oral, intravenous, subcutaneous, intramuscular, inhalation, and implantation routes.
SCD also has a variety of presentations, including pompholyx/dyshidrosis/vesicular dermatitis, maculopapular eruption, chronic pruritus, exfoliative erythroderma/toxiderma, chronic urticaria, erythema multiforme and vasculitis, hyperkeratotic papules of the elbows, acute generalized exanthematous pustulosis, and pruritus ani, according to Dr. Zippin.
SCD should be considered when a patient has a positive patch test to an allergen that is known to cause SCD, and does not clear after avoiding cutaneous exposure to the allergen, Dr. Zippin advised.
Patients will most often develop SCD from plants and herbs, Dr. Zippin noted. Chrysanthemums and chamomile tea are common culprits for compositae allergy and can trigger SCD; other causes are Anacardiaceae, Balsam of Peru, and propolis. Metals (nickel, cobalt, gold, and chromium), medications (aminoglycosides, corticosteroids, and ethylenediamine), and other sources (formaldehyde, propylene glycol in frozen foods, gallates, and methylisothiazolinone) can cause SCD as well.
Methylisothiazolinone in particular is a very common sensitizer, Dr. Zippin said. “If you have a patient who is positive to this, it’s almost always the cause of their problem.”
Balsam of Peru is in a number of different foods, and patients who need to follow a diet free of Balsam of Peru should avoid a long list of foods including citrus; bakery goods; Danish pastry; candy; gum; spices such as cinnamon, cloves, vanilla, curry, allspice, anise, and ginger; spicy condiments such as ketchup, chili sauce, barbecue sauce; chili, pizza, and foods with red sauces; tomatoes; pickles; alcohol (wine, beer, gin, vermouth); tea (perfumed or flavored); tobacco; chocolate and ice cream; and soft drinks (cola or spiced soft drinks).
Patients starting a nickel-free diet should avoid soy, peanuts and other nuts, legumes, chocolate, cocoa, oats, fish, and whole wheat flours. Any elimination diet should last for 3 months but should at least be tried for 3-4 weeks, with gradual reintroduction of foods suspected as triggers once per week. Any type I allergies that are discovered or suspected can be referred to an allergist for allergen challenge and desensitization therapy.
For more information, Dr. Zippin recommended the American Contact Dermatitis Society website for more information.
Dr. Zippin reported that he is the founder and holds stock options at CEP Biotech; is on the medical advisory board and receives stock options from YouV Labs., is a paid consultant and performs industry-sponsored research for Pfizer, receives stock options from Regeneron, and is on the medical advisory board for Hoth Therapeutics Inc. He is on the board of directors for the American Contact Dermatitis Society.