Patch Testing in Children
Allergic contact dermatitis (ACD) affects people of all ages. It is thought that ACD is underdiagnosed in the paediatric population (which is generally defined as individuals < 18 years) because of less frequent patch testing compared to adults. The international prevalence is thought to be increasing most likely related to a greater recognition of the condition. Children presenting with rashes are more likely to have underlying atopic dermatitis associated with skin barrier damage, which may facilitate sensitisation to allergens.
At the Skin Health Institute, 491 children were patch tested from 1993 – 2014 with a sensitisation rate of 60.4% while 61.6% of those reactions were deemed to be relevant.
Common allergens affecting children include:
- Nickel- Commonly found in jewellery, watch straps, toys, eye frames, clothing with nickel buttons
- Fragrance- Personal care products such as shower gels and shampoo, baby wipes, sunscreens, hand sanitisers
- Methylchloroisothiazolinone (MCI)/ methylisothiazolinone (MI- Commonly found in personal care products, sunscreens, shampoos, hand washes/ sanitisers, slime, some baby wipes, however it has largely been omitted from wipes in recent times
Patch testing remains the gold standard in the diagnosis of ACD in the paediatric population. Diagnosing ACD in children has been shown to significantly improve the quality of life for both children and their parents. Additionally, this has been linked to reduced healthcare related costs.
Patch testing in children is considered to be SAFE. Children are no more likely than adults to experience side effects. There is often a misconception that children should be tested to a weaker concentration of allergen than adults, but this is untrue. It is safe for children to be tested at the same concentration as adults. Â
Common diagnosis and allergens in Melbourne
From a retrospective study of paediatric data at the SHI, the most common diagnosis was endogenous eczema, followed by ACD and then ICD.
 The most common allergens are shown below:
1. Fragrance mix 1
2. 4-Phenylenediamine base (PPD)
3. Ammonium persulfate
4. Toluene-2-diamine sulfateÂ
5. Myroxylon pereirae (Balsalm of Peru)
6. Nickel sulfate
7. Colophony
8. House dust mite
9. Potassium dichromate
10. p-Aminophenol
Most common allergens compared by age are shown below.Â
0-5 years old
22 children tested
13 sensitised
11 with relevant reactions
Fragrances
Sunscreen
Preservatives
Benzophenone 3
Balsalm of peru
MCI/MI
Fragrance mix 1 + 2
Germall II
Nickel
Toluenesulfanide resin
Amerchol
6-10 years old
67 children tested
46 sensitised
25 with relevant reactions
Fragrances
Shoes
Plants
Colophony
Fragrance Mix I
Balsalm of Peru
Grevillia
Tinc Benz co
Abitol
Arnica montano
House dust mite
Lemon grasss oil
Potassium dichromate (0.25%
11-17 years old
402 children tested
238 sensitised
147 with relevant reactions
Fragrances
Metals
Preservatives
Occupational
High rates of ACD from PPD were found, resulting from occupational exposure to hair dye in hairdressing apprentices but also children sensitised to PPD in temporary tattoos. We do not always recommend patch testing in this situation because people may develop severe reactions. For more information about temporary tattoos please refer to module 3.1.
Following the review by Felmingham et al, the first Australian Paediatric Baseline Series was proposed, based on the most common and relevant allergens found. A smaller number of allergens was chosen given the smaller surface area available for testing in children and the fact that generally children would be unlikely to be exposed to certain allergens e.g. acrylates.
The Paediatric Baseline Series
Patch testing considerations
As with any patient with suspected ACD, a thorough history of product use and exposure analysis is required. Sources of exposure differ to adults, so it is important to ask parents or caregivers about the following:
- Personal care products – nappies, wipes, tapes and dressings, sunscreens
- School activities- art, sports, cooking etc.
- Hobbies/ sports – shin guards, splints, musical instrument mouthpieces, rosin
- Exposures from care givers
But it is also important to consider the basic patch testing principles such as:
- Reviewing clinical details such as history and examination that maybe suggestive of an ACD diagnosis e.g. history of temporary tattoo
- Eczema that is recalcitrant to therapy
- Occupational cases e.g. hairdressing apprentices
- Wacky; patches of dermatitis which is not explained clinically
When patch testing children, things to consider are:
- Smaller surface area – typical 6-year-old can fit maximally 40-60 allergens during patch testing- therefore allergens/patient products need to be tailored.
- Greater mobility which may cause patches to fall off
- recommend using extra tape
- Children may need to be distracted during patch application
Many children and their parents, associate allergy testing with prick testing and as a result be fearful of patch testing (thinking it may be painful). The use of demonstrating patches applied to the parents’ skin may help overcome this fear, as well as pre- patch testing information with photos.
References
- Felmingham C, Davenport R, Bala H, Palmer A, Nixon R. Allergic contact dermatitis in children and proposal for an Australian Paediatric Baseline Series. Australas J Dermatol. 2020;61(1):33-8.
- Jacob SE, Herro EM. Patch testing in young children should not be overlooked. Dermatitis. 2013;24(5):258-9.
- Goossens A. Skin allergy in children caused by consumer products. Expert Review of Dermatology. 2011;6(3):237-39.
- Yu J, Atwater AR, Brod B, Chen JK, Chisolm SS, Cohen DE, et al. Pediatric Baseline Patch Test Series: Pediatric Contact Dermatitis Workgroup. Dermatitis. 2018;29(4):206-12.
