A frantic mother brings her 6-week-old daughter to you for evaluation of a generalized scaly eruption which has blossomed over the last 10 days (Fig.1, 2). The baby is thriving and asymptomatic, and the skin lesions have defied therapy with topical antibiotics, topical antifungals, and emollients. What's the diagnosis?
Diagnosis and Clinical Presentation
On exam, she had generalized well-demarcated, discrete and confluent red papules and plaques with overlying silvery scale. Lesions extended to the intertriginous areas, face, and scalp. Bacterial and fungal cultures from macerated plaques in the skin creases were negative. A skin biopsy confirmed the clinical impression of infantile psoriasis. (there were pink and red well-demarcated, confluent papules and plaques with overlying white scale on her trunk and extremities and shiny macerated plaques in the intertriginous areas. The eruption continued to progress despite several days of oral fluconazole and topical nystatin. One week after her initial visit with you, the patient had well defined red plaques with silvery white scale that had spread to cover most of her body (Fig. 2). Bacterial and fungal cultures were negative. A skin biopsy and histopathologic study of the scale supported the clinical diagnosis of psoriasis.)
Epidemiology and pathogenesis
Psoriasis is a papulosquamous skin disorder that can develop at any age. In 2% of cases, the onset is before age 2; congenital cases have also been reported. The clinical pattern in this age group is variable which makes it difficult to distinguish from other more common infantile eruptions. In young infants, early lesions most commonly begin in the “napkin” or diaper area and then disseminate. Older infants and children with psoriasis can present with an itchy or an asymptomatic scaling eruption of the scalp, face, trunk and/or limbs. Guttate psoriasis can also occur following a streptococcal infection of the throat or perianal area. Rarely children with psoriasis develop erythroderma, generalized pustular psoriais, or isolate nail disease. Psoriasis is thought to result from T-cell mediated immune dysregulation leading to abnormal keratinocytic hyperproliferation. Psoriasis is more common in girls with a female to male ratio of 2:1 (1-3).
Seborrheic Dermatitis Seborrheic dermatitis (SD) is a red, scaly eruption that occurs primarily in the sebaceous gland rich areas of the body such as the scalp, face, post-auricular, and intertriginous areas (4-6). It is most commonly seen in infants and adolescents, and the clinical findings often overlap with psoriasis. The cause is not well understood but hormonal influences on sebum production and the yeast Pityrosporum ovale are possible pathogenetic factors. Infantile SD usually appears between the 2nd and 10th weeks of life and peaks at 3 months of age. It usually starts in the scalp or diaper area as red greasy plaques that are covered with yellowish brown crusts. Pruritis is usually mild or absent. The prognosis for infants with SD is excellent and the condition usually clears with or without treatment in 3-4 weeks. No treatment is medically necessary as the condition is self-limited. Treatment is warranted in cases of extensive inflammation or of high parental anxiety. Application of emollients, mineral oil, or baby oil to the crusts can aid removal with a brush. Shampooing with ketoconazole 2% appears to be safe and efficacious treatment for infants with SD on the scalp. Topical steroid use should be limited to cases with severe inflammation because of risk for systemic absorption. Atopic Dermatitis Atopic dermatitis (AD) is a very common childhood disorder with a peak prevalence of 20-25% in children from 5- 10 years old in industrialized countries (7, 10). The onset of AD occurs during infancy in about 60% of individuals. Pathogenesis is still not well understood but involves immune dysregulation and epidermal barrier dysfunction. During infancy, AD presents with intense pruritus and ill-defined red papules and plaques on the face and scalp which then extend to the trunk and extensor aspects of the extremities (Fig. 3). Generalized xerosis is also common. Scaling is fine and dry. Unlike infantile psoriasis and seborrheic dermatitis, the eruption in AD invariably spares the diaper area.5 Treatment included aggressive moisturization, topical anti-inflammatory medications such as topical steroids and topical calcineurin inhibitors, and careful monitoring and treatment of infection. Parent counseling regarding a consistent skin regimen, avoidance of irritants, and dealing with psychosocial issues is critical for effective management. AD is a chronic and recurrent, but most children outgrow the disease or improve markedly by adolescence. Pityriasis Rubra Pilaris Pityriasis rubra pilaris (PRP) is a rare red generalized papulosquamous dermatosis. The classic juvenile variant begins with hyperkeratotic follicular papules that progress in a cephalocaudal distribution to generalized erythroderma with typical “islands of sparing” (8). PRP was considered in the differential diagnosis of our patient because patches of uninvolved skin, or “spared islands” were noted (Fig. 4). PRP is a non-inherited disorder with no sex predilection. Prognosis is variable, with the majority clearing completely with appropriate treatment. Treatment with isotretinoin or etretinate has shown the best results. Langerhans Cell Histiocytosis In Langerhan’s cell histiocytosis (LCH), dendritic antigen-processing epidermal Langerhans cells infiltrate the skin and other organs (9). Lesions may be limited to the skin or skin lesions may be the first manifestation of disease. LCH can occur at any age but the peak incidence is between 1 and 4 years of age. Etiology is not clear, and investigators argue about whether it is a reactive or neoplastic process. Infants usually present with reddish-brown, purpuric, crusted papules or vesiculopapules on the scalp, behind the ears and/or in intertriginous areas. Red scaly papules, patches, and plaques are often crusted, infiltrated and hemorrhagic which helps to distinguish LCH from innocent, self-limited seborrheic dermatitis. Diagnosis is made by characteristic histology and identification of CD1a+ Langerhans cells by immunostaining. . Immunodeficiency Syndrome An immunodeficiency should be considered when infants have a generalized eczematous eruption reminiscent of AD that is recalcitrant to conventional treatment. The most common immune disorders that present with a generalized, pruritic eczematous eruptions include Wiskott-Aldrich syndrome, Omenn syndrome, severe combined immune deficiency (SCID), and Hyper IgE syndrome. Patients with an immune deficiency usually have one or more of the following associated features: hepatosplenomegaly, lymphadenopathy, recurrent infections, or failure to thrive. If an immunodeficiency is suspected, the patient should have a complete evaluation. Treatment is largely supportive and involves preventing and treating infections. In some cases bone marrow transplant is curative.
Treatment of psoriasis varies depending on age and extent of disease(1-3). First line therapy for mild disease is topical steroids. Tar, anthralin, salicylic acid, calcipotriol and UVB phototherapy are alternative options for treatment. Oral retinoids, anti-metabolites, and biologic agents are reserved for older children with more extensive disease. In severe reaclcitrant cases, these agents are used in young children.
Although most children with infantile psoriasis respond quickly and effectively to topical steroids, our patient failed to respond to aggressive mid and high potency topical steroid therapy. An immunologic evaluation of T-cell and B-cell function was normal. She subsequently began a course of oral prednisolone 1 mg/kg/day with modest improvement. When acitretin (oral retinoid) solution became available several days later, the patient was started on 0.5 mg/kg/day with a slow taper of the prednisolone. At her 4 and 8 week follow-up visits, she continued to improve dramatically.
2% of psoriasis develops before 2 years of age and should be considered in infants and children who present with discrete and confluent red plaques with overlying silvery scale particularly when there is a family history of psoriasis.
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