Atopic dermatitis facts
What is atopic dermatitis?
Atopic dermatitis is a common, often long-lasting skin disease that affects a large percentage of the world's population. It is a special type of hypersensitivity that includes asthma, inhalant allergies (hay fever), and a chronic dermatitis (eczema). There is a known hereditary component of the disease, and it is more common in affected families. Criteria that enable your doctor to diagnose it include the typical appearance and distribution of the rash in a patient with a personal or family history of asthma and/or hay fever.
The term atopic is from the Greek meaning "strange." The term dermatitis means inflammation of the skin.
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.
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 various 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.
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 is the difference between atopic dermatitis and eczema?
Eczema is a nonspecific term for many types of skin inflammation (dermatitis). There are different categories of eczema, which include allergic, contact, irritant, and nummular eczema, which can be difficult to distinguish from atopic dermatitis. These types of eczema are listed and briefly described below. Atopy is a medical syndrome that includes three associated conditions that tend to occur in the same individual: atopic dermatitis, inhalant allergies, and asthma. All three components need not be present in the same individual simultaneously.Types of eczema
How common is atopic dermatitis?
Atopic dermatitis is very common worldwide and increasing in prevalence. It affects males and females equally and accounts for 10%-20% of all referrals to dermatologists (doctors who specialize in the care and treatment of skin diseases). Atopic dermatitis occurs most often in infants and children, and its onset decreases substantially with age. Scientists estimate that 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. This means that more than 15 million people in the United States have symptoms of the disease.
What causes 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 hypersensitivity and an increased tendency toward itching. Evidence suggests that the disease is associated with other so-called atopic disorders such as hay fever (seasonal allergies) and asthma, which many people with atopic dermatitis also have. In addition, many children who outgrow the symptoms of atopic dermatitis go on to develop hay fever or asthma. Although one disorder does not necessarily cause another, they may be related, thereby giving researchers clues to understanding atopic dermatitis. It is important to understand that food sensitivities do not seem to be a major factor with most atopic dermatitis. This is an area of active research. Patients with atopic dermatitis seem to have mild immune system weakness. They are predisposed to develop fungal foot disease and cutaneous staphylococcal infections, and they can disseminate herpes simplex lip infections (eczema herpeticum) and smallpox vaccination (eczema vaccinatum) to large areas of skin.
While emotional factors and stress may sometimes exacerbate the condition, they do not seem to be a primary or underlying cause for the disorder.
Is atopic dermatitis contagious?
No. Atopic dermatitis itself is definitely not contagious, and it cannot be passed from one person to another through skin contact. There is generally no cause for concern in being around someone with even an active case of atopic dermatitis, unless they have active skin infections.
Some patients with atopic dermatitis get secondary infections of their skin with Staphylococcus ("staph"), other bacteria, herpes virus (cold sores), and less commonly yeasts and other fungal infections. These infections may be contagious through skin contact.
What are atopic dermatitis symptoms and signs?
Although symptoms may vary from person to person, the most common symptoms are dry, itchy, red skin. Itch is the grand hallmark of the disease. Typical affected skin areas include the folds of the arms, the back of the knees, wrists, face, and hands. Less commonly there may be cracks behind the ears, and various other rashes on any part of the body.
The itchy feeling is an important factor in atopic dermatitis, because scratching and rubbing in response to itching worsen the skin inflammation that is characteristic of this disease. People with atopic dermatitis seem to be more sensitive to itching and feel the need to scratch longer in response. They develop what is referred to as the "itch-scratch" cycle. The extreme itchiness of the skin causes the person to scratch, which in turn worsens the itch, and so on. Itching is particularly a problem during sleep, when conscious control of scratching decreases and the absence of other outside stimuli makes the itchiness more noticeable. Many patients also notice worsening of their itch in the early evening when they get home from work or school when there are less external stimuli to keep them occupied.
How atopic dermatitis affects the skin can be changed by patterns of scratching and resulting skin infections. Some people with the disease develop red, scaling skin where the immune system in the skin becomes very activated. Others develop thick and leathery skin as a result of constant scratching and rubbing. This condition is called lichenification. Still others develop papules, or small raised bumps, on their skin. When the papules are scratched, they may open (excoriations) and become crusty and infected. The box below lists common skin features of the disease. These conditions can also be found in people without atopic dermatitis or with other types of skin disorders.Photo of irritant contact eczema on the hands
Can atopic dermatitis affect the face?
Yes. Atopic dermatitis may affect the skin around the eyes, the eyelids, the eyebrows, and lashes. Scratching and rubbing the eye area can cause the skin to change in appearance. Some people with atopic dermatitis develop an extra fold of skin under their eyes, called an atopic pleat or Dennie-Morgan fold. Other people may have hyperpigmented eyelids, meaning that the skin on their eyelids darkens from the inflammation or hay fever (allergic shiners). Patchy eyebrows and eyelashes may also result from scratching or rubbing.
The face is very commonly affected in babies, who may drool excessively, and become irritated from skin contact with their flowing saliva.
The skin of a person with atopic dermatitis loses too much moisture from the epidermal layer. Some patients with atopic dermatitis lack a protein called fillagrin that is important in retaining moisture. This defective genetic trait allows the skin to become very dry, which reduces its protective abilities. In addition, the skin is very susceptible to recurring disorders, such as staphylococcal and streptococcal bacterial skin infections, warts, herpes simplex, and molluscum contagiosum (which is caused by a virus).Skin features of atopic dermatitis
What are the stages of atopic dermatitis?
Atopic dermatitis affects each child differently, both in terms of onset and severity of symptoms. 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. Severe cases of atopic dermatitis may affect growth, and the child may be shorter than average.
The disease may go into remission (disease-free period) for months or even years. In most children, the disease disappears 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. Sleep patterns and work performance may be affected, and long-term use of medications to treat the condition may cause complications. Adults with atopic dermatitis also have a predisposition toward irritant contact dermatitis, especially if they are in occupations involving frequent hand wetting, hand washing, or exposure to chemicals. Some people develop a rash around their nipples. These localized symptoms are difficult to treat, and people often do not tell their doctor because of modesty or embarrassment. Adults may also develop cataracts that are difficult to detect because they cause no symptoms. Therefore, the doctor may recommend regular eye exams.
How do physicians diagnose atopic dermatitis?
Atopic dermatitis is generally diagnosed based on a physical examination and visual inspection of the skin by a physician or dermatologist. Additionally, the history given by the patient and contributory family history help to support the diagnosis. A physician may ask about any history of similar rashes and other medical problems, including hay fever (allergies) and asthma.
A skin biopsy (a sample of a small piece of skin that is sent to the lab for examination under the microscope) is rarely helpful to establish the diagnosis. Many patients with severe atopic disease may have elevated numbers of a certain type of white blood cells (eosinophils) in the blood and/or and elevated serum IgE levels. These tests can support the diagnosis of atopic dermatitis. Additionally, skin swab (long cotton tip applicator or Q-tip) samples may be sent to the lab to exclude staphylococcal infections of the skin which may complicate atopic dermatitis.
Since itching tends to be the dominant symptom of the disease for many patients, it is not possible to say all itching is atopic dermatitis. Itching may be seen in many other medical conditions that have nothing to do with eczema. Each patient experiences a unique combination of symptoms, and the symptoms and severity of the disease may vary over time. The doctor bases the diagnosis on the individual's symptoms and may need to see the patient several times to make an accurate diagnosis. It is important for the doctor to rule out other diseases and conditions that might cause skin irritation. In some cases, the family doctor or pediatrician may refer the patient to a dermatologist or allergist (allergy specialist) for further evaluation.
Skin scratch/prick tests (which involve scratching or pricking the skin with a needle that contains a small amount of a suspected allergen) and blood tests for airborne allergens generally are not as useful in diagnosing atopic dermatitis. Positive skin scratch/prick test results are difficult to interpret in people with atopic dermatitis and are often inaccurate.Major and minor features of atopic dermatitis
Some minor features
What factors can aggravate atopic dermatitis?
Many factors or conditions can intensify the symptoms of atopic dermatitis, including dry skin, small changes in temperature, the low humidity of winter or cold weather, wool cloths, and other irritating skin conditions. These factors may further trigger the itch-scratch cycle, further stimulating the many times already overactive immune system in the skin. Repeated aggravation and activation of the itch-scratch cycle may cause further skin damage and barrier breakdown. These exacerbating elements can be broken down into two main categories: irritants and allergens. Emotional factors and some infections can also influence atopic dermatitis.
What are skin irritants in patients with atopic dermatitis?
Irritants are substances that directly affect the skin, and when used in high enough concentrations with long enough contact, cause the skin to become red and itchy or to burn. Specific irritants affect people with atopic dermatitis to different degrees. Over time, many patients and their families learn to identify the irritants that are most troublesome to them. For example, wool or synthetic fibers may affect some patients. Rough or poorly fitting clothing can rub the skin, trigger inflammation, and prompt the beginning of the itch-scratch cycle. Soaps and detergents may have a drying effect and worsen itching, and some perfumes and cosmetics may irritate the skin. Exposure to certain substances (such as chlorine and solvents) or irritants (such as dust or sand) may also aggravate the condition. Cigarette smoke may irritate the eyelids.Common irritants
What are allergens?
Allergens are substances from foods, plants, or animals that provoke an overreaction of the immune system and cause inflammation (in this case, the skin). Inflammation can occur even when the person is exposed to small amounts of the allergen for a limited time. Some examples of allergens are pollen and dog or cat dander (tiny particles from the animal's skin or hair). When people with atopic dermatitis come into contact with an irritant or allergen to which they are sensitive, inflammation-producing cells permeate the skin from elsewhere in the body. These cells release chemicals that cause itching and redness. As the person scratches and rubs the skin in response, further damage occurs.
Certain foods occasionally may act as allergens and trigger atopic dermatitis or exacerbate it (cause it to become worse). Food allergens clearly play a role in a small number of cases of atopic dermatitis, primarily in infants and children. An allergic reaction to food can cause skin inflammation (generally hives), gastrointestinal symptoms (vomiting, diarrhea), upper respiratory tract symptoms (congestion, sneezing), and wheezing. The most common allergy-causing (allergenic) foods are eggs, peanuts, milk, fish, soy products, and wheat. Although the data is not compelling, some studies suggest that mothers of children with a family history of atopic diseases should avoid eating commonly allergenic foods themselves during late pregnancy and while they are breastfeeding the baby. Although not all researchers agree, most experts think that breastfeeding the infant for at least four months may have a protective effect for the child. New lines of evidence even support exposing young children to normal environmental contaminants. Such exposures may prevent the development of atopic dermatitis.
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 o