Xu Weiwei (徐薇薇), Ci Lingling (蔡玲玲), Wu Di (吳迪), Wu Meiho (吳美超),Li Ping (李萍), Wng Yn (王燕), nd Peng Dengf (彭登發(fā)) ＊

Psoriasis is a common, chronic and recurrent inf l ammatory skin disease. The clinical manifestations usually include the red pimples, spots on the pimples covered with silver scales, with itching as its main feature. The pathogenesis of this disease is not clear,currently the disease is closely related to genetic,infection, drugs, mental and other factors. The incidence of psoriasis in children is 0.71%1. And there is an upward trend in past few years. The clinical manifestations of children with psoriasis are not typical,some only appear as erythema and pimples, occurring in the axillary, umbilical, groin and genital skin folds and other parts2. The purpose of the treatment is to control the disease, and delay the recurrence. Due to the special sensitivity and tolerance of drugs in children,the treatment programs of children are different from those of the adults. This article aims to summarize the treatment of psoriasis in children in China and abroad.

THE EXTERNAL TREATMENT

Emollients

Emollients have moisture and barrier effects, and is suitable for chronic and remission of psoriasis maintenance therapy. It forms a denser film on the surface of the skin, which will reduce the deeper evaporation of the skin, soften the skin, and increase the skin moisture3. Studies have shown that urea,nicotinamide, α-hydroxy acids and polyhydroxy acids can improve the lesions of psoriasis. Emollients can also increase the permeability of drugs, improve the efficacy of topical glucocorticoids, and even play a steroid-like effect4. Comparing with glucocorticoids and vitamin D3derivatives, emollients have fewer side effects and are uncomfortable5.

Vitamin D3 derivatives

Vitamin D3derivatives are against the inf l ammation,they can induce the differentiation of keratin and inhibit the proliferation of epidermal. Carbotriol is one of the common usages of vitamin D3derivatives, and it is suitable for mild to moderate plaque psoriasis.Skin burning sensation or irritation are its common side effects, especially the face and skin folds parts should avoid using it6. Long-term using of vitamin D3derivatives in children may cause the endogenous vitamin D reduction7.

Glucocorticoid

Glucocorticoids can inhibit the phagocytosis and presentation of the antigen by macrophage, interfere proliferation of lymphocyte, inactivate immune response, impede the proliferation of fi broblast and the synthesis with collagen, and block mitosis. According to the classification of psoriasis, different skin lesions should select different glucocorticoids, and it can effectively relieve the erythema, scaling and itching and other symptoms. General erythrodermic and pustular psoriasis can select a weak or less effective glucocorticoid, and the vulgar psoriasis can use the moderate or potent one; sensitive and wrinkled parts can apply the weak or moderate one; trunk, limbs,palmoplantar and scalp lesions can choose the powerful glucocorticoid8. The external use of glucocorticoids may cause skin atrophy, telangiectasia, folliculitis, dermatitis and other side effects9.

Immunomodulator

Calcineurin inhibitors include tacrolimus (0.03% and 0.1% ointment) and pimecrolimus (1% cream). It can inhibit the production of IL-2 and the activation and proliferation T cell by blocking Calcineurininhibitors.Besides, it can help to regulate the immune system,function, against the inflammation, relieve itching,which will effectively relieve the symptoms of children with psoriasis10. Of which 1% pimecrolimus and 0.03%tacrolimus are recommended for children over 2 years old, 0.1% tacrolimus is recommended for children over 15 years old. Such drugs have poor permeability to the hyperkeratosis type plaque psoriasis. After treatment,the affected part may feel like burning, itching and other local skin irritation, and those can be relieved by themselves11.

PHYSICAL THERAPY

The wavelength for the narrow-band UVB (NB-UVB)used is 311 nm, and it is the main physical therapy for psoriasis. The effectiveness of NB-UVB is the same with that in the earlier state of using photochemical therapy (PUVA), but the remission is shorter. NB-UVB can be used alone or combined with other external or internal drugs12. Children under 7 years old should avoid irradiation treatment, but it is suitable for quiescent psoriasis patients. And psoriasis patients in acute progressive period are forbidden to have the irradiation treatment13,14. Other studies have shown the total effective rate of NB-UVB is up to 88.6%. All children get different degrees of dry skin, itching, pigmentation after the treatment, some patients have the feeling of light burning, but it can be tolerated, and the above mentioned symptoms disappear when symptomatic treatment is taken away or the dose of exposure is reduced.

SYSTEMATIC TREATMENT

Methotrexate

Methotrexate work throughout reacting with the reversible dihydrofolate reductase. It interferes with DNA synthesis and repair, inhibits the proliferation of T, B lymphocytes15, which is suitable for moderate to severe psoriasis and refractory or disabling psoriasis.The recommended dosage for children is 0.2～0.7 mg/kg per week, at the beginning of 1.3～5.0 mg. It is required to adjust the dose according to blood, liver and kidney work and tolerance of drugs of the children in order to achieve the desired effect16. The most common side effect of methotrexate are the abnormalities of the liver enzyme, nausea and vomiting, and they will disappear after stopping using methotrexate. Severe adverse effects include liver poisoning, interstitial pneumonia,myelosuppression, photosensitivity and lymphoma17,18.

Cyclosporine

Cyclosporine is a selective T lymphocyte inhibitor,with the role of regulating cellular and humoral immunity, which is used in children with plaque-type,pustular-type, erythrodermic-type psoriasis19,20. Its effectiveness and side effects are related to the amount of Cyclosporine. During the treatment of psoriasis in children, small doses is used at the beginning,recommended 3～5mg / (kg·d), and gradually reduce the dose after the control of the disease17,21. The most common side reactions of using cyclosporineare include nausea, vomiting and diarrhea, and the situation can be restored after reducing the amount of medication15.Cyclosporins also have the risk of develop in grenal impairment, hypertension, skin cancer, lymphoid hyperplasia, etc..22

Tretinoin

Tretinoin has the role of regulating the growth and differentiation of epithelial cells and other cells,regulating the immune system and validation23. Oral Tretinoin is suitable for severe psoriasis in children when the traditional way is ineffective, and Etretinare drugs are commonly used24. Acitretin is suitable for the generalized pustular psoriasis, diffuse drip or thin plaque psoriasis25-27. The starting dose of Etretin is generally not more than 0.5～1mg / (kg·d), and the amount of dose should be reduced when the situation is improved. The maintenance treatment is generally 0.5mg/ (kg·d) for more than 2 months28. Wang JX studied the treatment of severe psoriasis in children, they take Etretin with 0.5～1.0mg/ (kg·d), and the effective rate is as high as 83.82%. The side effect of Tretinoin is mainly on the bones. They may also have dry cheilitis, skin itching and increasing the skin brittleness29.

Etancercept

Etancercept is a fusion protein of the tumor necrosis factorαP75 and the human-IgG1-Fc30. Clinical studies have shown that Etancercept is efficient on the moderate to severe plaque type psoriasis, and psoriatic arthritis16.According to the recommended method, administration of Etancercept is 0.4mg / kg, and the maximum dose is not more than 25mg, twice a week by subcutaneous injection31. Inf l iximab is the mouse protein that blocks the antagonistic function of the tumor necrosis factor alpha and the human-IgG1 chimeric monoclonal antibody. US FDA has approved the use of Inf l iximab in the treatment of chronic severe plaque psoriasis, and the effect is signif i cant32,33.

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