Dermatitis

Epidemiology

Dermatitis occurs in people of all ages and ethnicities. According to the National Institutes of Health, people who live in dry climates or in cities have a higher risk of developing atopic dermatitis. Approximately 20 percent of children suffer from some form of dermatitis, and some of them continue to have this condition as adults.

Atopic Dermatitis

Atopic dermatitis, often referred to as eczema, has a high prevalence in children, but may occur at any age. It is caused by a combination of genetic and environmental factors, and is often linked with allergies, asthma, and stress. The clinical appearance of atopic dermatitis may vary by the individual; however, the hallmark clinical picture is acute eruptions of erythematous (red), scaled, and pruritic (itching) plaques involving the antecubital fossa (inner arm crease) and popliteal fossa (behind the knee crease). The condition waxes and wanes and may have periods where the skin appears normal. Atopic dermatitis is usually controlled by identifying and avoiding triggers and maintaining the skin barrier with emollient moisturizers. In moderate to severe cases it may be necessary to treat the affected area with topical steroids or immunomodulators, and systemic antihistamines.

Contact Dermatitis

Contact dermatitis is the skin's innate inflammatory reaction to an offending external environmental chemical trigger. There are three main subcategories of contact dermatitis: urticarial, irritant, and allergic.

On the other hand, with contact urticaria, the least common, hives develop by an IgE-mediated immediate type mechanism to chemical triggers such as environmental allergens or certain foods. The classical clinical presentation is characterized by a local tingling sensation and localized redness and swelling. It is usually treated with topical anti-itch creams, oral antihistamines. In moderate to severe cases systemic steroids may be necessary. As this is an immediate type reaction it may develop rapidly. A common example of contact urticaria is the allergic reaction to latex.

In irritant contact dermatitis (ICD), the most common form, irritants penetrate the skin and in doing so may remove the protective oils and moisture from the skin's outer layer. This results in chemical injury to the superficial layers of the skin with subsequent inflammation. The dermatitis in ICD usually appears within 48 hours of exposure to a caustic chemical and is generally limited to the areas of the skin which was in contact with the irritant. There may be variation in the clinical appearance depending on the strength of the chemical trigger and the strength of the skin barrier to sustain the insult. ICD can be caused by soaps, detergents, and antiperspirant, among others.

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