Atopic dermatitis

What is atopic dermatitis?

Atopic dermatitis is a common, often persistent skin disease that affects a large percentage of the world's population. The term atopicis from the Greek meaning "strange." The term dermatitis means inflammation of the skin. Many physicians and patients use the term eczema when they are referring to this condition. In atopic dermatitis, the skin becomes extremely itchy and inflamed, causing redness, swelling, vesicle formation (minute blisters), cracking, weeping, crusting, and scaling. This type of eruption is termed eczematous. In addition, dry skin is a very common complaint in almost all those afflicted with atopic dermatitis.

What is ”atopic march”?

The concept of the ”atopic march” is compelling: seeing children who start with atopic dermatitis (eczema), then develop asthma, and finally develop allergic rhinitis (hay fever) is a fairly common pattern. Some have discussed that increased gut permeability (”leaky gut”) with or without actual food allergies or intolerances may come even before the eczema, and there are some studies that support this idea.
Although atopic dermatitis can occur in any age, most often it affects infants and young children. Occasionally, it may persist into adulthood or may actually appear at that time. Some patients tend to have a protracted course with ups and downs. In most cases, there are periods of time when the disease is worse, called exacerbations or flares, which are followed by periods when the skin improves or clears up entirely, called remissions. Many children with atopic dermatitis enter into a permanent remission of the disease when they get older, although their skin may remain somewhat dry and easily irritated.

How common is atopic dermatitis?

Atopic dermatitis is very common worldwide and increasing in prevalence. Atopic dermatitis occurs most often in infants and children, and its onset decreases substantially with age. Of those affected, 65% of patients develop symptoms in the first year of life, and 90% develop symptoms before the age of 5. Onset after age 30 is less common and often occurs after exposure of the skin to harsh conditions. People who live in urban areas and in climates with low humidity seem to be at an increased risk for developing atopic dermatitis. About 10% of all infants and young children experience symptoms of the disease. Roughly 60% of these infants continue to have one or more symptoms of atopic dermatitis even after they reach adulthood.

What are the causes of atopic dermatitis?

The cause of atopic dermatitis is not known, but the disease seems to result from a combination of genetic (hereditary) and environmental factors. There seems to be a basic cutaneous hypersensitivity and an increased tendency toward itching. Multiple factors can trigger or worsen atopic dermatitis, including low humidity, seasonal allergies, exposure to harsh soaps and detergents, and cold weather. Environmental factors can activate symptoms of atopic dermatitis at any time in the lives of individuals who have inherited the atopic disease trait.

What are atopic dermatitis symptoms and signs?

Although symptoms and signs may vary from person to person, the most common symptoms are dry, itchy, red skin. Itch is the hallmark of the disease. Typically, affected skin areas include the folds of the arms, the back of the knees, wrists, face, and neck.

Atopic dermatitis seems to have a differing pattern of involvement depending on the age of a patient.

• In infants:

Atopic dermatitis typically begins around 6 to 12 weeks of age. It may first appear around the cheeks and chin as a patchy facial rash, which can progress to red, scaling, oozing skin. The skin may become infected. Once the infant becomes more mobile and begins crawling, exposed areas such as the knees and elbows may also be affected. An infant with atopic dermatitis may be restless and irritable because of the itching and discomfort. Many infants improve by 18 months of age, although they remain at greater than normal risk for dry skin or hand eczema later in life.

• In childhood:

The rash tends to occur behind the knees and inside the elbows, on the sides of the neck, and on the wrists, ankles, and hands. Often, the rash begins with papules that become hard and scaly when scratched. The skin around the lips may be inflamed, and constant licking of the area may lead to small, painful cracks. In those with more heavily pigmented skin, especially the face, areas of lighter skin color appear. This condition is called pityriasis alba. It is usually self-limited and the color will eventually normalize.

• After puberty:

Although a number of people who developed atopic dermatitis as children also experience symptoms as adults, it is less common for the disease to show up first in adulthood. The pattern in adults is similar to that seen in children; that is, the disease may be widespread or limited. In some adults, only the hands or feet may be affected and become dry, itchy, red, and cracked.

How to prevent and treat atopic dermatitis?

The most important is to prevent and avoid aggravating factors for atopic dermatitis. Patients with atopic dermatitis should limit exposure to environmental and chemical factors known to cause exacerbations. These include dry skin, quick changes in temperature, the low humidity encountered during cold weather, and wool clothing. Common irritants are the following: wool or synthetic fibers, dust or sand, dust mites, cigarette smoke, animal fur or dander.

Most experts think that breastfeeding the infant for at least six months may have a protective effect for the child.

Most patients can be successfully managed with proper skin care and lifestyle changes and do not require the more intensive treatments discussed. Healing the skin and keeping it healthy are of primary importance both in preventing further damage and enhancing the patient's quality of life. Developing and following a daily skin-care routine is critical to preventing recurrent episodes of symptoms. The key factor is proper bathing and the application of an emollient to the wet skin without towel drying. Generally, an effective emollient is a reasonably stiff ointment or cream. People with atopic dermatitis should avoid hot baths and showers. The doctor may recommend limited use of a mild bar soap or non-soap cleanser because soaps can be drying to the skin. Once the bathing is finished, apply an emollient immediately without towel drying. This restores the skin's moisture and inhibits the evaporation of water, increasing the rate of healing, and establishing a barrier against further drying and irritation. The moisturizer should be as free of fragrances and chemicals as possible.

If the disease does not respond to mild local over-the-counter treatment then a physician is required. With proper treatment, most symptoms can be brought under control within three weeks.

Corticosteroid creams and ointments are the most frequently used treatment. Since many of these are quite potent it will be necessary to have frequent physician visits to assure that the treatment is successful.

Tacrolimus (Protopic) and pimecrolimus (Elidel) are non-steroid topical ointments that contain molecules that inhibit a substance called calcineurin which is important in inflammation. They rather expensive topical medicated creams that are used for the treatment of atopic dermatitis. They are particularly effective in when used on the faces of children since they seem less likely to produce atrophy. These new drugs are referred to as "immune modulators."

Phototherapy is treatment with light that uses ultraviolet A or B light waves or a combination of both. This treatment can be an effective treatment for mild to moderate dermatitis in older children (over 12 years old) and adults.

Is changing the diet necessary?

The importance of food allergy in atopic dermatitis is controversial. If a food allergy is suspected, it may be helpful to keep a careful diary of everything the patient eats, noting any reactions. Identifying the food allergen may be difficult and require supervision by an allergist if the patient is also being exposed to other allergens. One helpful way to explore the possibility of a food allergy is to eliminate the suspected food and then, if improvement is noticed, reintroduce it into the diet under carefully controlled conditions. A two-week trial is usually sufficient for each food. If the food being tested causes no symptoms after two weeks, a different food can be tested in like manner afterward. Likewise, if the elimination of a food does not result in improvement after two weeks, other foods may be eliminated in turn.

Changing the diet of a person who has atopic dermatitis may not always relieve symptoms. Restricted diets often are emotionally and financially difficult for patients and their families to follow. Unless properly monitored, diets with many restrictions can also contribute to nutritional problems in children.

Practical advice for parents:
• Give lukewarm baths.
• Apply an emollient immediately following the bath.
• Keep a child's fingernails filed short.
• Select soft cotton fabrics when choosing clothing.
• Consider using antihistamines to reduce scratching at night.
• Keep the child cool; consider a humidifier.
• Attempt to distract the child with activities to keep him or her from scratching.