Topical Therapies
For children with mild to moderate psoriasis, topical therapies are first line. Despite being off label, topical corticosteroids are the mainstay of therapy for localized psoriatic plaques in children. Topical vitamin D analogues—calcitriol and calcipotriol/calcipotriene—are highly effective and well tolerated, and they frequently are used in combination with topical corticosteroids. Topical calcineurin inhibitors, namely tacrolimus, also are used off label but are considered first line for sensitive regions of the skin in children, including the face, genitalia, and body folds. There currently is limited evidence for supporting the use of the topical vitamin A analogue tazarotene in children with psoriasis, though some consider its off-label use effective for pediatric nail psoriasis. It also may be used as an adjunct to topical corticosteroids to minimize irritation.
Although there is no gold standard topical regimen, combination therapy with a high-potency topical steroid and topical vitamin D analogue commonly is used to minimize steroid-induced side effects. For the first 2 weeks of treatment, they each may be applied once daily or mixed together and applied twice daily. For subsequent maintenance, topical calcipotriene may be applied on weekdays and topical steroids only on weekends. Combination calcipotriol–betamethasone dipropionate also is available as cream, ointment, foam, and suspension vehicles for use on the body and scalp in children aged 12 years and older. Tacrolimus ointment 0.1% may be applied in a thin layer up to twice daily. Concurrent emollient use also is recommended with these therapies.
Health care providers should educate patients and guardians about the potential side effects of topical therapies. They also should provide explicit instructions for amount, site, frequency, and duration of application. Topical corticosteroids commonly result in burning on application and may potentially cause skin thinning and striae with overuse. Topical vitamin D analogues may result in local irritation that may be improved by concurrent emollient use, and they generally should be avoided on sensitive sites. Topical calcineurin inhibitors are associated with burning, stinging, and pruritus, and the US Food and Drug Administration has issued a black-box warning related to risk for lymphoma with their chronic intermittent use. However, it was based on rare reports of lymphoma in transplant patients taking oral calcineurin inhibitors; no clinical trials to date in humans have demonstrated an increased risk for malignancy with topical calcineurin inhibitors.10 Tazarotene should be used cautiously in females of childbearing age given its teratogenic potential.
Children younger than 7 years are especially prone to suppression of the hypothalamic-pituitary-adrenal axis from topical corticosteroid therapy and theoretically hypercalcemia and hypervitaminosis D from topical vitamin D analogues, as their high BSA-to-volume ratio increases potential for systemic absorption. Children should avoid occlusive application of topical vitamin D analogues to large areas of the skin. Monitoring of vitamin D metabolites in the serum may be considered if calcipotriene or calcipotriol application to a large BSA is warranted.
Light-Based Therapy
In children with widespread psoriasis or those refractory to topical therapy, phototherapy may be considered. Narrowband UVB (311- to 313-nm wavelength) therapy is considered a first-line form of phototherapy in pediatric psoriasis. Mineral oil or emollient pretreatment to affected areas may augment the efficacy of UV-based treatments.11 Excimer laser and UVA also may be efficacious, though evidence is limited in children. Treatment is recommended to start at 3 days a week, and once improvement is seen, the frequency can be decreased to 2 days a week. Once desired clearance is achieved, maintenance therapy can be continued at even longer intervals. Adjunctive use of tar preparations may potentiate the efficacy of phototherapy, though there is a theoretical increased risk for carcinogenicity with prolonged use of coal tar. Side effects of phototherapy include erythema, blistering hyperpigmentation, and pruritus. Psoralen is contraindicated in children younger than 12 years. All forms of phototherapy are contraindicated in children with generalized erythroderma and cutaneous cancer syndromes. Other important pediatric-specific considerations include anxiety that may be provoked by UV light machines and inconvenience of frequent appointments.