Psoriasis is a common skin disease in children although the prevalence is much lower than in adults. The total rate of psoriasis in children younger than 18 years found in Germany was 0.71% while this was 1.4% in Great Britain. In the Netherlands and the US even lower figures were found and juvenile psoriasis seemed to be less common in the US among African Americans than among Hispanics and Caucasians.The prevalence among girls is normally higher than in boys. Hospital based studies from Africa show prevalences of 1.5% in Egypt, 0.9% in Nigeria, 0.05% in Mali and 3.5% in Kenya.Population based studies among schoolchildren in West and Eastern Africa showed very low prevalences.
Etiology and pathogenesis
Psoriasis is characterized by the proliferation of keratinocytes and inflammatory cell infiltration of the dermis and epidermis. This reaction is caused by dermal infiltration of T lymphocytes and macrophages and leads to a fast turnover and hyperplasia of the epidermis. This results in a chronic inflammatory condition affecting the skin, nails, and joints.Patients are genetically predisposed to psoriasis. Psoriasis in adults is associated with comorbidities such as obesity, hyperlipidemia, diabetes mellitus (metabolic syndrome), rheumatoid arthritis and Crohn’s disease. Physical trauma may trigger psoriatic lesions at sites of injury (Koebner’s phenomenon). Other triggers are antimalarials, lithium, beta blockers, stress, infections such as streptococcal angina and a cooler climate.
The plaque type; this is the most frequently observed variant of psoriasis. It is characterized by sharply demarcated erythematous plaques covered by silvery white scales which shows the typical candle wax phenomenon after scratching. Lesions commonly appear on the elbows, knees, scalp, umbilicus, and lumbar area. The scalp is the most frequently affected site of involvement in pediatric psoriasis. Facial and intertriginous lesions may be difficult to differentiate from seborrheic eczema if there are no other typical psoriasis lesions. Guttate psoriasis; is more frequently seen in children and consists of numerous papules and plaques (like “drops”) all over the body. Guttate psoriasis is often preceded by a streptococcal throat infection. The prognosis is good, with spontaneous remissions in weeks to months. The inverse type of psoriasis; in this type of psoriasis the lesions appear as sharply defined erythematous plaques which show no or minimal scaling in intertriginous areas like the groin and armpits. Erythrodermic psoriasis; nearly the whole body surface can be involved but this is rare in children. Nail involvement (especially the fingernails) is uncommon in children with psoriasis. If it occurs nail-pitting is the common manifestation. Onycholysis and the “oil drop” sign are rare. Psoriatic arthritis; is an extracutaneous manifestation which is rare among children in Africa. A recent African review suggested an association between psoriatic arthritis and HIV infection.
- Tinea capitis
- Tinea corporis
- Seborrheic dermatitis
- Lichen planus
- Pityriasis rosea / secondary Syphilis (d.d. Psoriasis guttata)
- Discuss the chronic character (“ come and go”) of the disease with the patients and the parents/caretakers. Explain that psoriasis is not contagious but can be triggered by an infection
- Approximately 70 to 80 percent of all patients with psoriasis can be treated adequately with use of topical therapy!
- Salicylic acid 5-10% in an oil, lotion, cream or ointment base 2x daily to reduce the scaling
- A moderate to strong topical topical steroid like betamethason ointment 2x daily on the lesions. Cannot be used continuously for a long time because of side effects.Can be used in combination with salicylic acid 2-10% ointment.
- Coal tar 5-10% ointment or sulphur 5% in coal tar 5-10% for the night
- Vitamin D3 analogue like calcipotriol 2x daily on the lesions, especially with plaque psoriasis. Can be used in combination with local corticosteroids
- Anthralin 0.1-1% cream or ointment.especially for plaque psoriasis. Has to be wiped or washed off after 10-60 minutes. Not always suitable for children because of the irritative reaction
- Find the possible bacterial sources of streptococcal infection (pharyngeal and perianal) and treat with antibiotics like erythromycin, penicillin or cephalosporines.
- If possible refer the patient to a dermatologist for phototherapy (UVB is the preferred form of phototherapy for pre-adolescent pediatric psoriasis)
- Methotrexate: can be given for severe cases of guttate psoriasis in children who are unresponsive to antibiotics, topical treatment and UVtherapy and to children with severe arthropathic psoriasis.
- Dosage: 0.3 mg/kg weekly dose of methotrexate, not exceeding the maximum standard dose of 22.5 mg weekly. Daily supplement with folic acid, except on the day of methotrexate therapy.
- Ciclosporin: is an appropriate therapy for severe guttate psoriasis in children
- Dosage : 1–5 mg/kg per day is used for both maintenance and crisis therapy. The renal function tests (creatinine) should be regularly checked.
- Biologic therapies: These therapies are very expensive and can, in the case of psoriasis, only be given by a dermatologist.
- ↑ Augustin M, Glaeske G, Radtke MA et al. Epidemiology and comorbidity of psoriasis in children. Br J Dermatol 2010; 162: 633-6.
- ↑ Gelfand JM, Weinstein R, Porter SB et al. Prevalence and treatment of psoriasis in the United Kingdom: a population-based study. Arch Dermatol 2005; 141: 1537-41.
- ↑ de Jager ME, van de Kerkhof PC, de Jong EM et al. Epidemiology and prescribed treatments in childhood psoriasis: a survey among medical professionals. J Dermatolog Treat 2009; 20: 254-8.
- ↑ 4.0 4.1 Tollefson MM, Crowson CS, McEvoy MT et al. Incidence of psoriasis in children: a population-based study. J Am Acad Dermatol 2010; 62: 979-87.
- ↑ Wu JJ, Black MH, Smith N et al. Low prevalence of psoriasis among children and adolescents in a large multiethnic cohort in southern California. J Am Acad Dermatol 2011; 65: 957-64.
- ↑ El-Khateeb EA. The spectrum of paediatric dermatoses in a university hospital in Cairo, Egypt. J Eur Acad Dermatol Venereol 2011; 25: 666-72.
- ↑ Mahe A, N'diaye HT, Bobin P. The proportion of medical consultations motivated by skin diseases in the health centers of Bamako (Republic of Mali). Int J Dermatol 1997; 36: 185-6.
- ↑ Ogunbiyi AO, Daramola OO, Alese OO. Prevalence of skin diseases in Ibadan, Nigeria. Int J Dermatol 2004; 43: 31-6.
- ↑ 9.0 9.1 Ouedraogo DD, Meyer O. Psoriatic arthritis in Sub-Saharan Africa. Joint Bone Spine 2012; 79: 17-9.
- ↑ Hogewoning AA, et al. Skindiseases among schoolchildren in Ghana, Gabon and Rwanda.August 2012.Accepted for publication in the International Journal for Dermatology
- ↑ 11.0 11.1 11.2 Schon MP, Boehncke WH. Psoriasis. N Engl J Med 2005; 352: 1899-912.
- ↑ Gottlieb AB, Chao C, Dann F. Psoriasis comorbidities. J Dermatolog Treat 2008; 19: 5-21.
- ↑ 13.0 13.1 Stahle M, Atakan N, Boehncke WH et al. Juvenile psoriasis and its clinical management: a European expert group consensus. J Dtsch Dermatol Ges 2010; 8: 812-8.