Eczema

What Is It?

Eczema, the most common type of skin inflammation (dermatitis), refers to several conditions that share a pattern of changes in the surface of the skin. Eczema first appears as an episode of itching and redness of the skin. You also may have tiny bumps or blisters. When it develops into a long-term condition (chronic eczema), it leads to thickening skin, scaling, flaking, dryness and color changes. There are many types of eczema, depending on the cause, shape and location of the rash. Most are related to allergies or to contact with irritating substances. Some are associated with underlying medical conditions that cause fluid retention in the legs. In the United States, eczema affects approximately 10% of the population.

• Atopic eczema (atopic dermatitis) - This type of eczema comes and goes repeatedly, and usually occurs in people who have a genetic (inherited) tendency to have allergies. In about 70% of cases, the person (or a family member) has allergic asthma, hay fever or food allergies. Atopic eczema appears early in life, usually in babies between 2 months and 18 months old. In babies, atopic eczema primarily affects the face, neck, ears and torso. It also appears on the tops of feet or the outside of the elbows. Atopic eczema in older children, teenagers and adults, usually involves the skin inside the creases of the inward bend of the elbow, as well as the knee, ankle or wrist joints, the hands, and upper eyelids.

• Contact dermatitis - When irritants touch the skin, they can produce two types of contact dermatitis. One is irritant contact dermatitis, which is the direct irritation of the skin. Irritant contact dermatitis can be caused by prolonged contact with irritants such as detergents, bubble bath, harsh soap, sweat, saliva, or urine. The second type of contact dermatitis is allergic contact dermatitis, which is an allergic reaction in the skin. This occurs in people who have an allergy to a specific substance. Each year, some type of skin allergy affects about 70% of people in the United States. The most common allergens are poison ivy, poison oak and poison sumac. Other substances that can trigger skin allergies include some materials used to build homes and offices, cleaning products, deodorants, cosmetics and medications. Dermatitis of the earlobes can be caused by an allergy to earrings containing nickel. Chemicals in fragrances, skin cream and lotions, shampoos and shoes or clothing can cause allergic reactions.

• Hand eczema - Limited to the hands, this type of eczema can be related to atopic eczema or it can occur because of repeated hand washing or exposure to strong detergents. Occasionally, hand eczema is caused by an allergy, such as to latex.

• Nummular eczema - This eczema causes coin sized patches of irritated skin, typically on the legs, arms or chest. It usually occurs in adults. It can be related to atopic dermatitis and, less often, allergic contact dermatitis. In a few cases, it represents an allergic reaction to a fungal infection such as athlete's foot. In this case, nummular eczema still appears typically on arms, legs or chest, even if the fungal infection is elsewhere on the body.

• Asteatotic eczema - This eczema dries the skin, causing fine cracks in the skin, usually first involving the lower legs, where there are fewer oil glands. It commonly occurs in the elderly, especially during winter months spent indoors in low humidity environments.

• Stasis dermatitis - Occurring on the calves, ankles and feet of people who have poor blood circulation in the lower legs, this type of dermatitis has leg swelling leads to itching, fine red bumps, skin redness or darkening and, sometimes, weeping sores.

• Lichen simplex chronicus - This eczema is a reaction to repeatedly scratching or rubbing of the skin in one location. A nervous scratching habit can lead to thickened, discolored skin on the wrist, ankle, groin or back of the neck. Skin picking can lead to smaller bumps of the same type of rash called prurigo nodularis.

• Seborrheic dermatitis (seborrhea) - doctors consider this a type of eczema, although it creates a greasier rash than usual for eczema. This scaly dermatitis commonly appears on the scalp of infants (as cradle cap) or as dandruff in adults. Probably triggered by the skin yeast, Pityrosporum ovale, it commonly affects the face or neck around the nose and at the scalp line.