Atopic Dermatitis

10


Atopic Dermatitis




Introduction



• Common inflammatory skin disease that affects 10–25% of children and 2–10% of adults in most high-income and some low-income countries.


• Eczematous dermatitis characterized by intense pruritus and a chronic or chronically relapsing course.


• Sequelae often include sleep disturbances, psychological distress, disrupted family dynamics, and impaired functioning at school or work.


• Onset usually in infancy or early childhood, with development in the first year of life in >50% and before 5 years of age in >85% of affected individuals.


• Often accompanied by other atopic disorders such as asthma and allergic rhinoconjunctivitis (hay fever), which develop in an age-dependent sequence referred to as the atopic march (Fig. 10.1).



image


Fig. 10.1 The atopic march.


• Atopy is linked to the presence of allergen-specific serum IgE antibodies, which exist in ~70% of individuals who meet diagnostic criteria for atopic dermatitis (AD) (Table 10.1).



• The ‘hygiene hypothesis’ postulates that decreased exposure to infectious agents in early childhood increases susceptibility to atopic diseases.


• Both a genetic predisposition and environmental triggers (e.g., irritation, epicutaneous sensitization, microbial colonization) have pathogenic roles in AD.


• Loss-of-function variants in the filaggrin gene (FLG), which encodes a protein important to epidermal barrier function, represent a major predisposing factor for AD that is present in 20–50% of AD patients of European or Asian descent; these FLG variants are also implicated in ichthyosis vulgaris.



Clinical Features and Disease Stages of AD



• Pruritic eczematous lesions are often excoriated and exist on a spectrum of acuity:


– Acute lesions: edematous, erythematous papules and plaques that may have vesiculation, oozing, and crusting.


– Subacute lesions: erythematous patches or plaques with scaling and variable crusting.


– Chronic lesions: thickened plaques with lichenification (increased skin markings) as well as scaling.


• Small perifollicular papules (papular eczema) are especially common in patients with darkly pigmented skin.


• Regional variants of AD are depicted in Fig. 10.2.



• Post-inflammatory hyper-, hypo-, or (in severe cases) depigmentation may be seen upon resolution of AD lesions (Fig. 10.3).



• DDx: outlined in Table 10.2.



• AD is divided into infantile, childhood, and adolescent/adult stages with characteristic morphologies and distributions (see Fig. 10.2).


Tags:
Apr 22, 2016 | Posted by in Dermatology | Comments Off on Atopic Dermatitis

Full access? Get Clinical Tree
Get Clinical Tree app for offline access