Atopic dermatitis

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Atopic dermatitis

Atopic dermatitis is a common chronic dermatitis with a relapsing course, which is associated with intense itching. It may occur at any age, most cases arising before the age of 5 years, though. The disease is based on an inherited genetic disposition, but its clinical manifestation is also triggered by factors such as aeroallergens, food allergens, cigarette smoke, sweat, irritants as well as stress and depression. There are three stages in atopic dermatitis: infantile, childhood and adulthood. Up to 80% of patients with atopic dermatitis develop allergic rhinitis or asthma later in childhood or during adolescence. Many patients experience an improvement in their skin involvement during childhood or adolescence, but up to 40% of patients with childhood atopic dermatitis will continue to have the disease as adults or will have recurrences later in life.

Clinical picture:

Acute lesions include intensely itching erythematous papules, vesicles, scaling and crusts. Subacute lesions present with erythematous papules and plaques, scaling and excoriation. Chronic lesions show hyperkeratotic plaques, papules and lichenification. Postinflammatory hyper- or hypopigmentation may follow recurring skin lesions.
Intense pruritus and xerosis cutis are hallmarks of atopic dermatitis. Other associated clinical features include keratosis pilaris (horny plugs within hair follicle orifices), palmoplantar hyperlinearity, pityriasis alba (patches of hypopigmentation with fine scaling) and the Dennie-Morgan infraorbital fold.

Distribution:

The infant stage starting usually during the third month is characterised by lesions on the face, scalp and extensor surface of the extremities, the lesions being rather exsudative and acute in character. In childhood, the skin lesions show a similar distribution to those in adulthood, manifesting in the flexural areas and posterior neck. Marks of the adult stage are a flexural distribution, hand and/ or foot dermatitis and periocular involvement. Some adults have a head and neck distribution. In severe disease, a widespread skin involvement up to generalised erythroderma may occur.

Diagnosis:

The diagnosis of atopic dermatitis is based primarily on clinical manifestations plus personal and family history and on the exclusion of other diseases. Diagnostic features have been published by Hanifin and Rajka in 1980 and have also been suggested by the American Academy of Dermatology.
An elevation of total or allergen-specific serum IgE is present in 70 – 80% of patients with atopic dermatitis and is a feature in supporting the diagnosis.

Differential diagnoses:

Eczematous skin diseases such as seborrhoeic dermatitis, allergic or irritant contact dermatitis, nummular dermatitis, asteatotic eczema and lichen simplex chronicus should be excluded. Significant differential diagnoses are palmoplantar psoriasis (if the palms and/ or soles are affected), scabies in children and cutaneous T-cell lymphoma in adults. Infectious skin diseases besides scabies such as dermatomycosis as well as primary immunodeficiencies such as Wiskott-Aldrich syndrome, severe combined immunodeficiency (SCID) and DiGeorge syndrome are also possible differential diagnoses. Genetic disorders (Ectodermal dysplasia, Netherton’s syndrome, phenylketonuria, ataxia telangiectasia, Hartnup disease), immunological disorders (dermatomyositis, dermatitis herpetiformis) and malignancies other than cutaneous T-cell lymphoma (e.g. Langerhans cell histiocytosis) should also be taken into consideration.