Contact dermatitis in children

History points

Targeted history should be guided by the patient’s age group, lifestyle, clinical presentation, such as the area involved, and duration of lesions. Pertinent questions regarding treatment history, personal hygiene products, clothes, shoes, socks, sleep mats, objects in their rooms, etc., should be asked.^[3] Exacerbating and triggering factors if noticed by parents as well as if the lesions are better during school time or during home time can give us clues. Exposures from pets, peers, caregivers, etc., are also important and should be explored during history-taking. Hence, it is essential that we tailor our questions to have a full understanding of a child’s daily activities. The following are some key points that can guide us in history.

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Figure 1:

Irritant contact dermatitis in the diaper area in a child with history of diarrhea.

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• Infants and toddlers – diapers [Figure 2], wipes, baby powder, creams, massage oils [Figure 3], toilet training [Figure 4], new clothes, and use of products by their caregivers

• School-aged children – toys and crafts, sports, crayons, slimes, instruments played by children, and electronic use

• Adolescents – hair dye, jewelry, cosmetics, henna, sports, household chores, and electronic use.

Clinical presentation

• Duration of exposures

• Sites of involvement: Distribution may be patchy or generalized; the most common sites of involvement are the face and extremities. Special attention to the diaper area is to be given, as ACD is more common in this area in younger children. Apart from that, hand dermatitis, feet dermatitis, eyelid dermatitis, lips and peri-oral dermatitis, anogenital dermatitis, earlobe dermatitis, neck dermatitis, etc., can be a presentation of ACD. The term “ectopic dermatitis” is used when varnish in nail paint is responsible for ACD of other parts, like eyelids.^[17]

• Clinical characteristics of lesions: Acute lesions can present with pruritic, erythematous, and edematous papules/plaques/vesiculobullous lesions. Chronic lesions present with eczematization, lichenification, fissures, and hyperpigmentation. “Holster sign,”^[7,18] referring to the contact allergy to rubber in undergarments affecting the waistline and proximal thighs, has been described with disposable napkins.

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Figure 2:

Contact dermatitis due to diaper wearing involving convexities of the inguinal area and sparing the folds.

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Figure 3:

Diffuse erythema with scaling over the trunk in an infant post-massage with mustard oil.

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Contact dermatitis in patients with AD

Because of the barrier defects in AD, the skin is more sensitive to ICD due to external insults in comparison to ACD. In Indian studies,^[1,2] there has been no statistical difference in positive patch tests between two groups – patients with atopy and patients without atopy. However, it has been suggested that a lack of filaggrin expression allows haptens to come in contact with the antigen-presenting cells of the epidermis easily. Furthermore, AD and ACD are now considered to have shared Th1, Th2, and Th17 pathways.^[19] A recent study^[20] has found that patients with atopy had more than one positive patch test, which was statistically significant in comparison to the control group without atopy. They also reported that they had more generalized distribution of lesions and positive patch test to bacitracin (found in topical antibiotics), carba mix (found in rubber products such as pacifiers, elastic bandages, balloons, toys, sport equipment, and sponges), and cocamidopropyl betaine (used for its tear free properties in shampoos) were significantly increased in patients with AD. Topical medications used in AD induce sensitization and may be responsible for ACD. Topical antibiotics-induced sensitization may result in cross-sensitization to oral antibiotics and must be kept in mind. Topical antivirals, antifungal, and other agents like corticosteroids^[21] may also be sensitizing. Even the labeled hypoallergenic products may result in sensitization and ACD due to newly identified allergens or preservatives. Whenever the dermatitis worsens with treatment and involves the flexures in the early childhood period, a patch test should be done to rule out ACD. AD can mask ACD; hence, a high index of suspicion is required.

Patch test

• When to test:^[3] A high index of suspicion is required. The following are some points that might help practitioners decide when to go for a patch test. Many studies have found that more than 50% of patients suspected to have ACD have positive patch test results.^[22,23]

  1. Persistent or recurrent dermatitis: Patch test when dermatitis persists or worsens despite standard therapy for more than 2 months or recurs despite treatment

  2. Unclear cause: Use patch testing to identify the allergen when the cause of dermatitis is unknown

  3. Suspected ACD: Patch test when ACD is suspected based on history (history of hobbies, recreational activities, occupation, personal care products, topical therapies, family history of allergies, and AD) and physical examination like atypical morphology, unusual site involvement, or distribution of lesions (head and neck, hands and feet, anogenital area), etc.

  4. Late onset AD/eczema: Onset in adolescence or adulthood

  5. Occupational exposure: Consider patch testing in children with occupational exposure (e.g., hairdressing and healthcare)

  6. Exposure to known allergens: Patch test when exposure to known allergens is suspected (e.g., nickel and fragrances)

  7. Treatment-resistant cases: Use patch testing in cases resistant to standard treatments

  8. Before using potentially allergenic products: Consider patch testing before using products with known allergens.

• Where to test: Limited space in case of children, especially in <6 years of age, is one of the problems that is faced practically. To overcome this, either allergens can be tested serially, or areas such as the thighs or abdomen can be used. Smaller pediatric-specific patch series can be used if available.

• Which kit/allergens to be included: Various pediatric baseline panels are available, like the Australian one with 30 allergens,^[24] the American with 38 allergens, and the European with 9 allergens and 12 supplemental allergens.^[25] There are specific series for diaper dermatitis, metal implants, and sunscreen ingredients for the pediatric population available. It has been observed that more than 20% children have positive patch tests to various allergens outside of the standard panel.^[26] However, in India, no specific patch test kits for children are available. Most common and newly emerging allergens with their sources are elaborated in Tables 1^[3,27,28] and 2 ^[3] respectively. If not included in the standard series, these allergens can be tested by repeated open application tests. Nickel remains a common allergen. Atopy patch tests can be considered if the history is suggestive.^[29]

• Tapes to be used to fix the allergens: Should be hypoallergenic

• Interpretation.

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Figure 4:

Toilet seat dermatitis.

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Based on the European Society of Contact Dermatitis,^[30] North American Contact Dermatitis Group,^[31] and International Contact Dermatitis Research Group,^[32] patch test interpretation is summarized in Table 3. False-negative reactions can occur due to a lower concentration of the allergens or treatment with immunosuppressive drugs, phototherapy, or sun exposure. Interpretations of patch test optimally should be done at 48 hours;^[29] however, earlier reading at 24 hours may be required in younger age and delayed reading at 1–3 weeks for delayed reactions (neomycin, metals, corticosteroids, and preservatives).^[33]

• Relevance^[34]

Patch test results should be interpreted in the context of the patient’s history and clinical presentation. A positive reaction does not always indicate clinical relevance. Review of product ingredients and current as well as past exposure also needs to be taken into consideration. There are three categories of relevance as follows:

1. Definite: Patch test or use test with offending product is positive.

2. Probable: Patch test is positive, offending allergen is present in the products to which the patient is exposed, and clinical presentations align with the exposure.

3. Possible: Patch test is positive, and the patient might have been in contact with the allergen in the exposed material.

• Practical points – A photo patch test may be done if indicated. If the back is involved with dermatitis, it can be cleared for patch testing with soaks and topical steroids. Repeated open application tests with suspected products can be performed on a 2.5 cm area on the non-sun-exposed part of the forearm for 2 weeks. Left-on products are to be left on, while rinse-off products are to be washed off to reflect daily use.

• Test while on treatment: Topical steroids should be stopped before 7 days of the patch test.^[35] Oral agents should be tapered and discontinued before patch testing, and the duration to test can be calculated according to their half-life. Dupilumab is not contraindicated and can be continued.^[36] However, few reports of recall of ACD at the patch test site with dupilumab are there, and hence, more data are needed to derive its impact.^[37]