Pediatric Psoriasis

Angie L. Busch, BA¹; Jennifer M. Landau, BS¹; Megan N. Moody, MD, MPH¹; Leonard H. Goldberg, MD^1,2,3
1DermSurgery Associates, Houston, TX, USA
²Department of Dermatology, Weill Cornell Medical College, The Methodist Hospital, Houston, TX, USA
³Department of Dermatology, The University of Texas Medical School at Houston, Houston, TX, USA

ABSTRACT

Several variants of psoriasis are seen in children, the most prevalent types include plaque, guttate, and psoriatic diaper rash; pustular and erythrodermic psoriasis are less frequently observed. Genetic susceptibility and environmental triggers are both involved in the development of this autoimmune disease. As well as improving symptoms, a treatment plan should strive to identify and eliminate precipitating factors. Topical medications are the first choice therapy for children with psoriasis. Systemic agents are used to treat more severe cases. Patient education and supportive care should be incorporated into the treatment plan.

Key Words: adolescent, children, psoriasis

Introduction

Psoriasis is a common condition that affects about 3.5% of the population.¹ In greater than 33% of patients, the initial presentation of psoriasis occurs within the first two decades of life.^2-5 It is estimated that 10% of patients develop psoriasis before the age of 10.⁶ In a review of 1262 cases of psoriasis, initial disease onset occurring before the age of 2 years was found in 14-27%.⁷ Children present with the same clinical variants of psoriasis seen in adults, though they may differ in distribution, morphology, and natural history.⁵

Etiology

Psoriasis is a T-cell mediated chronic inflammatory condition characterized by keratinocyte hyperproliferation, vascular endothelial proliferation, and inflammatory cell infiltration.^8,9 The exact cause and pathogenesis of psoriasis are not well understood, but are known to be multifactorial, having both genetic and environmental influences.⁹ Seventy-one percent of children with psoriasis have a positive history for psoriasis in a first degree relative.⁷ The PSORS1 gene has been shown to be a major genetic determinant of Type 1 early onset non-pustular psoriasis.^5,10 HLA-Cw6 is the major disease allele at the PSORS1 locus that confers susceptibility to early onset disease.^2,5,11,12

Exogenous and endogenous factors, such as upper respiratory infection, emotional stress, skin injury, and drugs, can precipitate and exacerbate psoriasis in children.^2,6,8,13 Streptococcal pharyngitis and perianal streptococcal dermatitis are common causes of guttate psoriasis in children.^2,7,8 Frequency of sore throat and skin trauma leading to an exacerbation of psoriasis is greater in pediatric onset psoriasis than adult onset.^5,13 The appearance of new lesions in times of emotional stress is also more common in pediatric patients.¹³ Injury or irritation of normal skin can induce new psoriatic lesions at the site, known as the Koebner phenomenon. Antimalarials and the withdrawal of corticosteroids play a significant role in rebound psoriasis and the induction of childhood psoriasis, whereas β-blocking agents and lithium are recognized triggers for psoriasis in adult patients.^11,14

Presentation

Classic psoriasis presents as sharply demarcated, deep red plaques with silvery scales.⁹ The presentation in children may be atypical, thus making a diagnosis difficult in such cases; however, there are a few clinical features that can aid in identification. The Auspitz sign, which is pinpoint bleeding upon removal of scales, is characteristic of psoriasis.^2,15 Nail changes, such as oil spots, onycholysis, subungual hyperkeratosis and pitting (the most common finding), are frequently observed in adolescents with psoriasis and are valuable clues in establishing diagnosis.^2,8,9,16,17

Psoriasis often presents differently in children than in adults. Involvement of the face and flexural regions are more common in children than adults, and psoriatic lesions in the diaper area are prevalent during infancy.⁸ Plaque-type psoriasis is the most common variant in both adults and children, however, lesions in children are smaller, thinner, and less scaly than those seen in adults.^2,5,7 Pustular and erythrodermic psoriasis are less frequently seen in pediatric than adult patients. Though rare in occurrence, there are also reports of congenital^6,18 and naevoid¹⁹ forms of psoriasis.

Plaque-type psoriasis is the most prevalent variant that affects children. Plaque psoriasis routinely affects the scalp. Scalp involvement characterized by pityriasis amiantacea (thick, adherent white scales that encase the hair shaft) may lead to temporary hair loss and visible psoriatic alopecia.^2,8 Plaque psoriasis can also affect the face, as well as extensor and flexor surfaces of the knees and elbows.^2,9

Psoriatic diaper rash is the next most common variant, with highest prevalence in children under the age of 2 years.^5,7 Psoriatic diaper rash features a bright red, well-demarcated, glazed, diaper rash that may be followed by widespread dissemination of small psoriasis-like lesions.² This clinical variant can be differentiated from irritant diaper dermatitis by its unique presentation and poor response to conventional treatment for diaper dermatitis.²

Guttate type psoriasis presents as annular, localized, red to salmon colored plaques with hyperkeratosis, commonly located on the trunk, abdomen, and back.⁸ Streptococcal pharyngitis and perianal dermatitis frequently precede abrupt appearances of guttate psoriasis.²⁰ Acute guttate psoriasis that is preceded by an upper respiratory infection may resolve spontaneously after 3-4 months; however, a significant portion of patients eventually develop chronic plaque disease.^2,9

Pustular and erythrodermic psoriasis are less frequently seen in children than adults.^2,9 Pustular psoriasis is distinguished by the presence of sterile pustules on erythematous skin; the pustules may be either localized or generalized.² Generalized pustular psoriasis in children has a more benign course than in adults.²¹ Annular pustular psoriasis, a manifestation of generalized pustular psoriasis, occurs more frequently in children than in adults.^2,22 It is characterized by annular lesions with erythematous, scaly, and pustular margins. Erythrodermic psoriasis presents as erythema on >90% of the body surface area with less scales than plaque psoriasis.²¹

Treatment

When treating children with psoriasis, it is important to educate both patients and parents about the nature of the disease. It must be made clear that psoriasis is a chronic skin disorder without a permanent cure and, therefore, the goal of treatment is to establish disease control and prolong periods between flares.²³ Treatment results may vary from flattened plaques and reduced visibility of lesions (e.g., less redness and scale) to complete remission.² Proper education about the disease and treatment options often enhances the compliance of patients and their parents.^2,9

The patient's age, quality of life factors, Psoriasis Area and Severity Index (PASI) score, and therapeutic preferences should all be considered when determining treatment selection.^5,8 The majority of children have mild disease that can be successfully treated with topical agents. Systemic drug therapy in children is generally reserved for severe disease that is resistant to other treatments.⁵ A prevention strategy should aim to control and reduce known exogenous and endogenous factors that trigger or contribute to disease exacerbation, like skin trauma, emotional stress, aggravating drugs, and upper respiratory infections.¹³

A chronic, visible condition like psoriasis can have a significant impact on children's psychosocial development.²⁴ Through school years and adolescence, children may require substantial family and professional support to cope with the psychological and social sequelae of psoriasis, particularly the negative reactions of other children.²⁵

Topical Medications

Corticosteroids

Corticosteroids have anti-inflammatory and antiproliferative properties that reduce erythema, scaling, and pruritus.^5,9 Corticosteroids have high acceptability among patients because they do not stain and are almost odorless. This acceptance combined with wide availability, ease of use, and faster onset of action make corticosteroids the first choice treatment of childhood psoriasis, especially in flexural disease.² Very high potency corticosteroids should be used only sparingly in combination or rotation with steroid sparing alternatives, such as coal tar, liquor carbonis detergens, anthralin, calcipotriene (calcipotriol), and topical calcineurin inhibitors.⁵ Combination therapy can help reduce side-effects caused by topical steroids without reducing the efficacy of the treatment.⁹ Side-effects of topical steroids include skin atrophy, striae, telangiectasia, acneiform eruptions, and in rare cases, suppression of the hypothalamic-pituitaryadrenal axis may occur after prolonged widespread application or overuse, especially of potent preparations.^2,5 There are reports of tachyphylaxis associated with prolonged corticosteroid use in the treatment of psoriasis. However, some attribute this phenomenon to decreased adherence to long-term therapeutic regimens.^5,26,27 Treatment with corticosteroids should be gradually withdrawn to prevent rebound flares.⁹

Coal Tar

The use of coal tar, which is both antiproliferative and antipruritic, is limited by its strong odor and ability to stain. A modified coal tar preparation, liquor carbonis detergens (LCD), has largely replaced crude coal tar in outpatient settings because of its superior cosmetic acceptability.⁵ Coal tar is less irritating than calcipotriene and anthralin on the face and flexures, sites commonly affected in children.²⁵

Anthralin

Anthralin (dithranol) is a potent anti-inflammatory and antiproliferative agent. Its negligible systemic absorption makes it a safe and easy treatment option for children.⁵ Anthralin's use is limited due to its tendency to stain skin and clothing and irritate healthy skin. It is not recommended for application on the face, flexures and genitalia, and should not be used in erythrodermic or pustular psoriasis.⁹ In an open study of 58 children ages 5-10 years, remission was achieved in 47 patients (81%) using dithranol at concentrations up to 1%.²⁸

Calcipotriene

Calcipotriene (calcipotriol) is a vitamin D analogue that stimulates keratinocyte differentiation and inhibits DNA synthesis and proliferation.²³ It is considered to be a successful and safe treatment for children with mild to moderate plaque psoriasis involving <30% of the body surface.² Calcipotriene is non-staining and odorless.⁹ Potential side-effects include local intolerance or irritation.⁸

Topical Calcineurin Inhibitors

Tacrolimus and pimecrolimus are non-steroidal immunomodulating macrolactams that inhibit the production and release of interleukin-2 (IL-2) and subsequent T-cell activation and proliferation, through blockade of the enzyme calcineurin.⁵ They are particularly useful for treating pediatric psoriasis in areas where atrophy is a risk, such as the face, intertriginous regions, and the groin.⁹

Salicylic Acid

Salicylic acid is recommended for use on thick localized plaques.^2,5 However, salicylic acid should be avoided in infants and children less than 6 years of age, or otherwise used with caution, as there is a risk of percutaneous absorption and salicylate intoxication.^2,5

Phototherapy

Phototherapy is extensively used in adults and is a treatment option for children with widespread plaques.² Narrowband UVB (NB-UVB) phototherapy may be combined with topical therapies to enhance efficacy of both modalities and to reduce the NB-UVB dose and carcinogenic risk.^2,5 Psoralen + UVA (PUVA) therapy is not generally recommended in young children, but may be used in adolescents with caution.^5,9,25 When PUVA is administered, topical psoralens are chosen preferentially over oral psoralens to avoid gastrointestinal side-effects and the necessity to wear protective eye gear for 24 hours.^2,8 NB-UVB is considered the first-line phototherapy because it is as effective as PUVA, more convenient, and less carcinogenic.^5,29

Systemic Medications

Acitretin

Acitretin, a retinoid, is an effective treatment for severe plaque, pustular, and erythrodermic psoriasis in adolescents.⁵ It can be used as monotherapy or in combination with topical agents and NB-UVB phototherapy. Side-effects include cheilitis, pruritus, and hair loss.² Because of its high teratogenic risk, acitretin should be used with caution in girls of childbearing age and must be accompanied by oral contraceptive therapy, as well as counseling, to avoid pregnancy during and 3 years after the completion of treatment.³⁰ Long-term use can lead to premature epiphyseal closure and radiologic bone evaluations may be required.³⁰

Methotrexate

Methotrexate, a folic acid antagonist, is rarely used in children and reserved for severe psoriasis unresponsive to other treatments.^30,31 Side-effects include nausea, headache and gastrointestinal upset, which can be minimized with folic acid supplements.⁹ Regular screening of the patient's blood count, liver enzymes, and renal function is necessary to monitor for potential development of acute hematotoxicity and hepatotoxicity.^2,9

Cyclosporine

Cyclosporine is an immunosuppressant that can be used to treat extremely severe cases of pediatric psoriasis. The initial dose of cyclosporine is 3 mg to 5 mg/kg per day and should be gradually tapered to the lowest dose that can maintain disease control.^2,5 Major risks of hypertension and renal dysfunction necessitate close monitoring.

Biologics

Biologics are a class of drugs that include antibodies and fusion proteins targeting cytokines. Etanercept and infliximab are tumor necrosis factor-alpha inhibitors that are used for the treatment of pediatric autoimmune diseases. Etanercept is an effective method of treatment for moderate to severe plaque-type childhood psoriasis.^31,32 In a double-blind trial designed to assess the efficacy and safety of etanercept in children with plaque-type psoriasis, both non-infectious and infectious adverse effects from treatment were observed, the most serious of which were gastroenteritis and pneumonia.³² All adverse affects were resolved without sequelae.³²

Antibiotics and Tonsillectomy

Pharyngeal and perianal streptococcal infections may precipitate or exacerbate acute guttate and pustular psoriasis.²⁰ Antibiotics may be prescribed to treat patients with recurrence or flare of guttate psoriasis, and tonsillectomy may be considered for refractory psoriasis and recurrent tonsillitis.³⁰ However, these treatments are controversial, as there is a lack of controlled studies to support their efficacy.

Conclusion

Psoriasis is a life-long disease that often begins during childhood. In order to correctly diagnose and treat children and adolescents, it is important to recognize the different presentations of the disease in this cohort. Children with psoriasis, including their parents and caregivers, should be educated about the natural history and exogenous and endogenous factors responsible for increased disease morbidity, as well as receive support and counseling to help cope with their condition.

References

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In this issue:

1. UVA1 Phototherapy: A Concise and Practical Review
2. Pediatric Psoriasis
3. Update on Drugs and Drug News - January 2012