Atopic Dermatitis

Epidemiology

Atopic dermatitis affects 10% to 20% of children and 1% to 3% of adults in the United States and Europe [9], [10]. The prevalence is higher in developed countries and urban areas and in populations that move from an area of low to high prevalence. Atopic dermatitis is more prevalent in temperate compared with tropical climates, especially dry winter climates [11]. The condition is also more prevalent in children who belong to families with a smaller size, higher socioeconomic class, and who

Pathogenesis and etiology

The pathogenesis of atopic dermatitis involves complex interactions between susceptible genes, immunologic factors, defects in the skin barrier, skin infection, and environmental factors [1].

There is a strong genetic predisposition. Approximately 30% to 50% of children who have one affected parent and 50% to 80% who have two affected parents develop the disorder [15]. The risk is higher with a family history of maternal compared with paternal atopy [16], [17]. Atopic dermatitis has a high

Immunopathology

Clinically unaffected skin of patients who have atopic dermatitis shows mild epidermal hyperplasia and sparse perivascular infiltration of T-helper 2 cells in the dermis [2]. Acute skin lesions are characterized by intracellular and intercellular edema of the epidermis (spongiosis), which is a histologic hallmark of atopic dermatitis [56]. There is marked perivascular infiltration of T-helper 2 cells in the dermis. Eosinophils, neutrophils, and mast cells are rarely present [56]. Chronic atopic

Clinical manifestations

Approximately 60% of children who have atopic dermatitis manifest the disease during the first year of life, and an additional 30% do so before the age of 5 years [1], [57]. Intense pruritus and cutaneous reactivity are the hallmarks of atopic dermatitis [1]. Pruritus increases the susceptibility of the surrounding skin to react to minimal stimuli and to illicit an itch, a phenomenon known as allokinesis [56]. Pruritus is exacerbated by scratching, which causes release of substance P from

Diagnosis

The diagnosis of atopic dermatitis is clinical and based on the presence of typical features. Criteria to define atopic dermatitis were first established by Hanifin and Rajka (Table 1) [67]. Although these criteria are useful for epidemiologic and therapeutic studies, many of the features are not common in children [66], and the minor criteria have not been validated in several studies [66], [68], [69]. In 1994, the United Kingdom Working Party developed more practical criteria for the

Assessment of severity and pyschosocial impact

Several scoring systems have been developed for the assessment of disease severity in children who have atopic dermatitis. The SCORing of Atopic Dermatitis (SCORAD) system, Eczema Area and Severity Index (EASI) system, and the Nottingham Eczema Severity Score (NESS) system are user-friendly, reliable, and in popular use [50], [72]. These systems generate quantifiable data that are amenable to analysis [72].

The SCORAD score ranges from 0 to 103 and measures the extent and intensity of the skin

Differential diagnosis

The differential diagnosis includes seborrheic dermatitis, psoriasis, acrodermatitis enteropathica, scabies, immunodeficiency disorders, nummular eczema, and contact dermatitis [66], [97].

The lesion in seborrheic dermatitis is usually asymptomatic and consists of an accumulation of a greasy yellow scale. In contrast, the lesion in atopic dermatitis is pruritic, the scale is dry, and excoriations are frequent. The diaper area might be involved in seborrheic dermatitis, but is typically spared in

Complications

Bacterial infection, most commonly with S. aureus, is the main complication of atopic dermatitis [100]. Purulent oozing honey-colored crusts, folliculitis, and pyoderma suggest secondary infection with S. aureus (Fig. 6). The anterior nares are an important reservoir of S. aureus [101]. Eczema herpeticum (Kaposi varicelliform eruption), caused by herpes simplex virus, is a potentially dangerous complication [57]. Eczema vaccinatum, caused by variola virus, follows smallpox vaccination or

Diagnostic testing

The diagnosis is based on a careful history and a thorough physical examination. Laboratory tests are usually not required. The need for further diagnostic work-up should be decided on an individual basis and should depend on the severity of the atopic dermatitis and the suspected factors involved [55], [109]. Hypereosinophilia in patients who have atopic dermatitis is a nonspecific finding and is also seen in patients who have asthma, allergic rhinitis, parasitic infestation, Hodgkin disease,

Management

Successful treatment requires a comprehensive approach that includes education of patients and caregivers, avoidance of triggering factors, optimal skin care, and pharmacotherapy.

Prognosis

Atopic dermatitis is characterized by exacerbations and remissions. Ten-year clearance rates vary from 40% to 80% for atopic dermatitis that begins in childhood [126]. Poor prognostic factors include early age at onset, severe disease, family history of atopic dermatitis, and concomitant asthma or allergic rhinitis [36], [192].

Summary

Atopic dermatitis is an especially common and frustrating condition, and the prevalence is increasing. The disease can adversely affect the quality of life of patients and caregivers. Significant advances in our understanding of the pathogenesis have led to improvements in therapy. Patient and caregiver education, avoidance of potential triggering factors, optimal skin care, and pharmacotherapy offer the potential for good control for most patients.