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--A superficial inflammation of the skin with redness, edema, vesicles, crusting, scaling, and sometimes itching. Common types include atopic, contact, nummular, or seborrheic dermatitis, all of which may be acute or chronic in nature.

Causes and Incidence The cause of atopic dermatitis is unknown, but the condition is often associated with other atopic diseases such as allergic rhinitis, asthma, or hay fever; these individuals have high serum levels of IgE antibodies. The response is thought to be hereditary, and it is seen in infants, children, and adults. Contact dermatitis, which can be irritant or allergic in nature, is caused by contact with various biologic or chemical irritants, such as acids, alkalis, dyes, detergents, latex, metals, plant oils, and solvents. The etiology of nummular dermatitis is unknown, but the condition is associated with increased stress and winter weather and is most commonly seen in middle age. The cause of seborrheic dermatitis is also unknown; this condition is associated with hereditary factors and underlying neurologic disease and can be seen in neonates and children, as well as adults.

Disease Process The histologic agent causes inflammatory changes in the skin, including vasodilation, edema, mononuclear cell infiltration into the dermis and epidermis, and breakdown of the epidermal cells. This leads to the visible changes on the skin's surface (i.e., redness, swelling, oozing, crusting, scaling, and itching). If the process is repeated over a period of time, the epidermis thickens, producing hyperkeratosis and a chronic scaly appearance.

Symptoms

Atopic type

Constant itching that sets up an itch-scratch-rash-itch cycle; red, scaly papules that coalesce into plaques that ooze and crust; common sites are hands, face, and flexural areas

Contact type

Transient redness to bulla formation; itching is common; weeping, crusting

Nummular type

Sharply circumscribed, moist, oozing discoid plaques that later become dry and scaly

Seborrheic type

Dry, diffuse scaling of scalp; oozing, crusted, red-yellow scalp lesions or scaly plaques that recur; may be found in external ear canals, eyebrows, and nasolabial folds and on sternum

Potential Complications Secondary infection is the most common complication. Chronic dermatitis, which appears on the hands or feet, can restrict function and become crippling.

Diagnostic Tests Clinical evaluation with characteristic manifestations; detailed history to locate possible source of contact rash; patch test may isolate allergens; immunofluorescence will show elevated IgE in atopic dermatitis.

Treatments

Surgery

None

Drugs

Antipruritics for itching; topical/systemic corticosteroids to relieve inflammation; topical keratolytics to reduce scaling

General

Oils on affected areas; removal of irritant in contact dermatitis; daily use of seborrheic shampoos; humidification; cool, wet cloths on open lesions