Atopic Dermatitis

Abstract

Atopic dermatitis is one of the more common inflammatory dermatologic disorders with an estimated prevalence of 15%. It is thought to be primarily an inherited disease associated with a multitude of clinical manifestations; age at onset varies. Atopic dermatitis may coexist with allergic rhinitis/conjunctivitis and asthma, and these 3 conditions are referred to as the atopic triad. Some patients may develop 1, 2, or all 3 of these disorders, which do not necessarily have a parallel course. Atopic dermatitis is usually diagnosed on the basis of clinical findings obtained from the history and physical examination. Occasionally, laboratory tests such as determination of total or specific IgE levels are helpful, as is skin biopsy. Most affected patients have dry skin, are intolerant of harsh soaps and detergents, and report that wool clothing creates an itchy sensation on the skin. Pruritus may be severe and is often maximal in the fold or flexural areas of the sides of the neck and in the antecubital and popliteal fossae. Scratching the skin often causes thickened or “lichenified” areas, and secondary impetiginization from gram-positive bacteria (Staphylococcus aureus) is common. Other physical findings include excessive wrinkling of the skin over the extensor aspects of the hands and around the eyes, particularly the lower eyelid. This latter finding is referred to as Dennie-Morgan folds. Some patients have subtle circumoral pallor and may demonstrate white dermatographism on stroking of the skin, as opposed to the normal triple response of Lewis. Hand eczema may be the presenting sign, especially in persons who must wash their hands repeatedly throughout the day. Patients with atopic dermatitis have altered skin immunity manifested by increased susceptibility to infection with herpesvirus and bacteria. Rarely, those with severe atopy may develop a widespread herpetic infection of the skin known as eczema herpeticum or Kaposi varicelliform eruption. Patients with atopic dermatitis also have increased eosinophils in the skin and sometimes in the peripheral blood. Serum IgE levels are often elevated, and specific IgE levels to allergens may be increased. Furthermore, patients with atopic dermatitis have diminished ability for sensitization to topically applied allergens. This seems somewhat paradoxical but is another reflection of the altered immune status of such patients. The treatment of atopic dermatitis requires recognition of factors that aggravate and exacerbate the condition in a specific patient, including environmental and infectious factors. Contact irritants and allergens must be identified and removed. Treatment of the skin consists of hydrating lotions and creams, and topical corticosteroid or immunomodulating creams/ointments are used to decrease inflammation. Antihistamines may be therapeutic in some patients.