Atopic Dermatitis

Abstract

Atopy can be defined as a familial hypersensitivity of skin and mucous membranes against environmental substances, associated with increased immunogloblin E (IgE) production and/or altered unspecific reactivity in different organ systems, for example, skin in the case of atopic dermatitis (AD) and lung in the case of asthma. It is a chronic, highly pruritic, inflammatory skin disease frequently seen in patients with a history of respiratory allergy and allergic rhinitis. The prevalence of AD in children has been steadily increasing since 1920s, and it now affects more than 10% of children at some point during their childhood. The term atopic dermatitis was first introduced in 1933 in recognition of the close association between AD and respiratory allergy. However, there has been considerable debate over whether AD is primarily an allergen-induced disease or simply an inflammatory skin disorder found in association with respiratory allergy. Recent studies, however, suggest that the ­mechanisms underlying asthma and AD have greater similarities than differences. AD is a common, potentially debilitating condition that can compromise qualityof life. Its most frequent symptom is pruritus. Attempts to relieve the itch by scratching simply worsen the rash, creating a vicious circle. Treatment should be directed at limiting itching, repairing the skin, and decreasing inflammation when necessary. Lubricants, antihistamines, and topical corticosteroids are the mainstays of therapy. When required, oral corticosteroids can be used. If pruritus does not respond to treatment, other diagnoses, such as bacterial overgrowth or viral infections, should be considered. Treatment options are available for refractory atopic dermatitis, but these measures should be reserved for use in unique situations and typically require consultation with a dermatologist or an allergist. Allergic reactions play a role in some patients but not necessarily in all. In many patients different factors such as a ­disturbance of skin function, infection, and mental and/or physical stresses are potentially more relevant. Immunologic disturbances are reflected in the elevated IgE production and T-cell dysregulation observed in AD. Unspecific altered ­reactivity is reflected in increased releasability of chemical mediator-secreting cells and in bronchial, nasal, and skin hyperreactivity. Each disease that forms the atopic triad has important immunologic parallels. However, they involve a different regional sphere of immunologic influence, for example, the skin-associated lymphoid tissue in AD as opposed to bronchial-associated ­lymphoid tissue in asthma.