Topical Treatment of Psoriasis in Children

J. Coffey, MD, I. Landells, MD, FRCPC

Memorial University of Newfoundland, St. John’s, Newfoundland and Labrador, Canada

ABSTRACT

Psoriasis is a common dermatosis, affecting children in North America. Many papers have stressed the treatments available for adult psoriasis, but few have dealt with this disorder in children. Topical treatment modalities continue to be the first line therapy for childhood psoriasis. This paper summarizes the general topical treatments available including their clinical use, benefits, cost, and side-effects.

Key Words:
childhood psoriasis, topical treatments

Psoriasis is a common dermatosis affecting 1-3% of the North American population.^1,2 In children it is also very common, representing 4.1% of all childhood skin conditions, and usually occurring after 10 years of age; but 10% occur before age 10, and 2% before 2 years.^3-5 This disorder causes significant morbidity, social embarrassment, and financial burden.²

Childhood Psoriasis

In infants, psoriasis often starts in the diaper area, but a confident diagnosis at this stage is often difficult. Childhood psoriasis tends to be more extensive and severe than that seen in adults.⁶ However, systemic antipsoriatic modalities may have devastating and potentially irreversible side-effects that limit their use in children.⁷ Thus topical therapies are generally preferred in the pediatric population.

It is important to keep in mind that children are not simply small adults. There is a need for child and parental education, compliance, and cooperation. This is why, while being treated, children with psoriasis should be followed closely. Successful psoriasis treatment is a life-long task requiring major contributions from the family and physician, and failure to treat has been shown to have an adverse effect on quality of life in children.⁷

There are five forms of psoriasis: plaque psoriasis, guttate psoriasis, pustular psoriasis, inverse psoriasis and erythrodermic psoriasis. In children, the most common types of psoriasis are the guttate and chronic plaque types. Psoriatic arthritis is seen in approximately 6% of children and adults.^7,8

Signs and symptoms of psoriasis include erythema, scaling, skin thickening, and pruritus. Athorough physical examination should include assessment of joints, scalp, elbows, knees, nails, palms, and soles of the feet.^1,3,9

Triggers

Triggers of psoriasis include comorbid inflammatory diseases (e.g., Crohn’s disease, HIV); emotional stress; withdrawal of systemic corticosteroids; preceding streptococcal infections in the case of guttate psoriasis; climate (northern regions); drugs (e.g., lithium, antimalarials, systemic interferon, and betablockers); and physical trauma (e.g., pressure, friction, rubbing and scratching).^1,10,11 Exacerbating triggers are different in children and adults, with infections and trauma being the most common triggers in children.⁷

Pathogenesis

Psoriasis is a complex disorder that may undergo periods of waxing and waning, recurrence and regression, and involves variable body surface areas. Genetic studies have linked it to several chromosomal loci (HLA-Cw6, 17q25, 4q), and psoriasis is an immunologic disorder leading to secondary hyperproliferation of keratinocytes.¹² The normal turnover rate of keratinocytes from the basal cell layer to the stratum corneum is 28-44 days, but in psoriasis it is reduced to 4 days.² Abnormal keratinocyte differentiation and infiltration of inflammatory cells are also typical features.^11,13 Treatments available are designed to counteract one or more of these features.¹⁴

Treatment Options

Available treatment modalities target keratinocyte hyperproliferation, abnormal keratinocyte differentiation, and infiltration of inflammatory cells. Treatment options for children include:

• Topical treatments, e.g., corticosteroids (mild, mid and high potency agents), keratolytics, anthralins, coal tars, vitamin D analogs, retinoids, ureas, and emollients.^1,9,11,15 Many of these are available as ointments (cutaneous plaques), creams (intertriginous areas) and lotions (scalp) (see Table 1).
• Phototherapy (e.g., UVB with topical adjuvant therapy, topical or systemic PUVA in teenagers). Sunlight and phototherapy can be beneficial if multiple areas are affected, but care must be taken to apply sunscreen to all unaffected areas.
• Systemic therapies for severe, or resistant conditions (e.g., methotrexate, cyclosporine, retinoids, dapsone, hydroxyurea).^1,3,8,9,11

Topical Treatments

Therapy should start with a combination of emollients, topical corticosteroids and calcipotriol, with or without the addition of tar, salicylic acid, and other topical agents.^1,3 For severe or resistant forms systemic modalities should be implemented. The choice of therapeutic agent should be based upon the location and extent of the plaques, the resistance to previous modalities, the various side-effects (see Table 2), and the cost of treatment (see Table 3).¹ As a rule of thumb, ointments are more effective than creams, which are in turn, better than lotions. Other factors influencing the decision include the age of the patient, type of psoriasis, and associated medical disorders.

Topical Corticosteroids

Corticosteroid efficacy is related to potency and absorption into the skin. There are four potency levels: low, mid-, high and ultra. A mild potency corticosteroid should be used for delicate skin, e.g., on the face and genitals. Mid-potency corticosteroids should be used on the torso and extremities, and high potency corticosteroids should be used to treat recalcitrant plaques, as well as the palms and soles. In children, the least potent topical steroid that is effective should be used, and the strength tapered as the condition improves. When used chronically, or at high doses, they can cause skin atrophy, tachyphylaxis, acne, localized hypertrichosis, striae, telangiectasia, and purpura. The may also suppress the Hypothalamic-Pituitary-Adrenal axis.^{1,3,8,11,18,19}

Keratolytics

These preparations act by decreasing the cell-to-cell cohesion as measured by the ease by which layers of cells can be stripped from the surface of treated skin. Excessive use of salicylic acid in children can result in salicylates toxicity. The effect of these ointments in removing scales and relieving the symptoms of dryness is enhanced when used under an occlusive plastic dressing (i.e., saran wrap). Children are sensitive to alphahydroxy acid, and small areas of the skin should be tested before applying it over wide areas. Salicylic acid is commonly used in combination with other topical preparations (e.g., corticosteroids, tars, anthralins, emollients).^{1,3,8,11,18,19}

Anthralins

Anthralins are effective in inhibiting the hyperproliferative growth observed in psoriasis. Although it is an effective agent, it is not an ideal drug because of irritating and staining properties. Regardless of these shortcomings, it is the treatment of choice (in the US) for plaque psoriasis. These agents also have the benefit of synergistic effects when used in combination with UVB therapy, and salicylic acids. Emollients or suitable corticosteroid may be applied after the anthralin treatment has been washed off to potentiate the desired clinical outcome. Common side-effects include brownish staining of the skin, erythema, irritancy, and contact dermatitis.^{1,3,8,11,18,19}

Coal Tar

Tar products have both anti-inflammatory as well as antiproliferative effects. Their benefits are synergistic in combination with steroids, emollients, and especially UVB treatment. Coal tar can also be used effectively as a shampoo for psoriatic scalp lesions. Side-effects include folliculitis, contact allergic dermatitis, aggravation of acne, and photosensitization of the skin. Patients dislike it because it is messy, stains skin, clothing, and bathtubs, and has an unpleasant odor.^{1,3,8,11,18,19}

Table 2: Adverse Effects of Topical Psoriasis Medications ^{1, 3, 8, 11}

Calcipotriol

Calcipotriol, or Vitamin D analogues, act to inhibit proliferation, and promote differentiation of keratinocytes. They are slow acting, however, and results may not be noted for 6-8 weeks. Adverse effects include irritant dermatitis and hypercalcemia with high doses or extensive use. In view of the risk of hypercalcemia and high cost, this preparation is not recommended for patients with extensive psoriasis. However, the vitamin D analogue does not suppress the Hypothalamic-pituitary-adrenal axis, making its use in pediatric patients a good alternative to topical steroids. Calcipotriol has been commercially combined with topical steroids with success, but is not stable if compounded by an independent pharmacy. Pulse topical steroids with maintenance calcipotriol is becoming the standard therapy for mild-moderate plaque psoriasis.^{1,3,8,11,18,19}

Retinoids

Tazorotene and Retin-A® are actively involved in mediating cell differentiation, and decreasing cell proliferation. They are nonsensitizing, nonphototoxic, and nonphotoallergenic. Application is once daily to affected areas only, with clearing occuring in 12 weeks. The most common side-effect is local skin irritation, although pruritis, and photosensitivity may be observed. These agents used orally are teratogenic, and potentially have similar effects at high doses topically.^{1,3,8,11,18,19}

Ureas

Urea is aproteolytic at high concentrations. It is most useful when applied to thickened nails secondary to psoriasis. It has also been added to some topical glucocorticoid preparations and is useful in treating psoriatic plaques and ichthyosis. The most common side-effect experienced by some patients is local irritation.^3,8,18,19

Table 3: Cost (in USD) of topical psoriasis treatments.^20,23
* Cost of 15g of topical steroids (includes drug cost only)
** Cost of 50g or 50ml or 30-day supply — includes drug cost only (excluding topical steroids)

Emollients

Emollients are occlusive agents that make the skin soft and pliable by increasing hydration of the stratum corneum. They act to soften dry skin and relieve itching. Petrolatum is probably the most occlusive and therefore the best emollient available. In terms of efficacy, the more occlusive a preparation is, the more effective it is. In order to be most effective, emollients should be applied to damp skin. There are no reported side-effects, but they may be greasy and sticky, and patients may find it difficult to maintain compliance.^18,19

Cost of Psoriasis Topical Treatment

Competing therapies for the treatment of psoriasis have substantially different cost implications. Clearly, assessment of the cost and benefits of a treatment needs to consider all costs (direct and indirect) as well as objective measurement of benefit (decrease in morbidity) from the patient’s perspective. Topical corticosteroids vary in price from <$7 to >$34USD per month based on potency (cheaper for low potency) and vehicle (lotions more expensive than creams and ointment). The newest topical treatments (retinoids and Vitamin D analogues) can be extremely expensive with monthly costs exceeding $100. Other topical treatment options are comparable in price to the low potency steroids, although combination therapy is commonly used in resistant plaques and costs may become very high.^18,20,21

Conclusion

The treatment of psoriasis in children differs from that in adults. It is important to emphasize educating the family, dealing with emotional aspects of the disease, and eliminating triggering factors. Since psoriasis is a common dermatosis that can adversely affect the lives of children, these patients’ treatment should be active and effective. It is important to point out to patients that psoriasis is not contagious, that the disease can disappear in some cases, and that the doctor is there to help manage the problem. There is no cure, and this disease bears an enormous emotional and financial cost upon children and their families.

References

1. Fitzpatrick TB, Johnson RA, Wolff K. Color Atlas and Synopsis of Clinical Dermatology, Common and Serious Diseases. New York:McGraw-Hill (1997) pp. 76-92.
2. Federman DG, Froelich CW, Kirsner RS. Topical Psoriasis Therapy. Am Fam Physician 59(4):957-62, 64 (1999 Feb).
3. Buxton PK. ABC of Dermatology, 3rd ed. London:BMJ publishing group (1998) pp. 12-15.
4. Oranje AP, Marcoux D, Svensson A. Topical calcipotriol in childhood psoriasis. J Am Acad Dermatol 36(2 Pt 1):203-8 (1997 Feb).
5. Darley CR, Cunliffe WJ, Green CM, Hutchinson PE, Laber MR, Down N. Safety and efficacy of calcipotriol ointment (Dovonex) in treating children with psoriasis vulgaris. Br J Dermatol 135(3):390-3 (1996 Sep).
6. Salleras M, Sanchez-Regana M, Umbert P. Congenital Erythrodermic Psoriasis: Case Report and Literature Review. Pediatr Dermatol 12(3):231-4 (1995 Sep).
7. Burden AD. Management of psoriasis in childhood. Clin Exp Dermatol 24(5):341-5 (1999 Sep).
8. Sauer GC, Hall JC. Manual of Skin Diseases, 7th ed. Philadephia (PA):Lipincott-Raven Publishers (1996) pp.138-143.
9. Bork K, Brauninger W. Diagnosis and Treatment of Common Skin Diseases. Philadephia (PA):W.B. Saunders Company (1988) pp.120-121.
10. Seyger MM, van de Kerkhof PC, van Vlijmen-Willems IM, de Bakker E, Zwiers F, de Jong EM. The efficacy of a new topical treatment for psoriasis: Mirak. J Eur Acad Dermatol Venerol 11(1):13-8 (1998 Jul).
11. Pardasani AG, Feldman SR, Clark AR. Treatment of Psoriasis: An Algorithm Based Approach for Primary Care Physicians. Am Fam Physician 61(3):725-33 (2000 Feb).
12. Bhalerao J, Bowcock AM. The genetics of psoriasis: A complex disorder of the skin and immune system. Hum Mol Genet 7(10):1537-45 (1998 Apr).
13. Weinstein GD, Keueger GG, Lowe NJ, et al. Tazarotene gel, a new retinoid, for topical thrapy of psoriasis: Vehicle-controlled study of safety, efficacy, and duration of therapeutic effect. J Am Acad Dermatol 37(1):85-92 (1997 Jul).
14. Hagemann I, Proksch E. Topical treatment by urea reduces epidermal hyperproliferation and induces differentiation in psoriasis. Acta Derm Venerol 76(5):353-6 (1996 Sep).
15. Bondi EE, Jegasothy BV, Lazarus GS. Dermatology: Diagnosis and Therapy. Norwalk (CN):Appleton and Lange (1991) pp. 14-20.
16. Baker H, Pegum JS. Clinical Dermatology, 4th ed. London: Bailliere-Tindall Publishers (1989) pp.104-106.
17. Dezfoulian, B., et al., A new generation of hydrocolloid dressings in combination with topical corticosteroids in the treatment of psoriasis vulgaris. J Eur Acad Dermatol Venerol (1997).
18. Freedberg IM, Fitzpatrick TB. Fitzpatrick’s Dermatology in General Medicine, 5th Edition. NY:McGraw-Hill (1999).
19. Roenigk HH, Maibach, HI. Psoriasis, 3rd Edition, Revised and Expanded. NY:Marcel Decker, Inc. (1998).
20. Marchetti A, LaPensee K, An P. A Pharmacoeconomic analysis of topical therapies for patients with mild-to-moderate plaque psoriasis: A U.S. study. Clin Ther 20(4):851-69 (1998 Jul-Aug).
21. Gray J, Gillis AM, editors. Therapeutic Choices, 3rd edition. Ottawa: Canadian Pharmacists Association (2000).