Atopic dermatitis is a very common, often chronic (long-lasting) skin disease that affects a large percentage of the world’s population. It is also called eczema, dermatitis, or atopy. Most commonly, it may be thought of as a type of skin allergy or sensitivity. The atopic dermatitis triad includes asthma, allergies (hay fever), and eczema. There is a known hereditary component of the disease, and it is seen more in some families. The hallmarks of the disease include skin rashes and itching.
The word “dermatitis” means inflammation of the skin. “Atopic” refers to diseases that are hereditary, tend to run in families, and often occur together. In atopic dermatitis, the skin becomes extremely itchy and inflamed, causing redness, swelling, cracking, weeping, crusting, and scaling. Dry skin is a very common complaint and an underlying cause of some of the typical rash symptoms.
Although atopic dermatitis can occur in any age, most often it affects infants and young children. In some instances, it may persist into adulthood or actually first show up later in life. A large number of patients tend to have a long-term 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 dry skin, seasonal allergies, exposure to harsh soaps and detergents, new skin products or creams, 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 used as a general term for many types of skin inflammation (dermatitis) and allergic-type skin rashes. There are different types of eczema, like allergic, contact, irritant, and nummular eczema. Several other forms have very similar symptoms. The diverse types of eczema are listed and briefly described below. Atopic dermatitis is typically a more specific set of three associated conditions occurring in the same person including eczema, allergies, and asthma. Not every component has to be present at the same time, but usually these patients are prone to all of these three related conditions.
Types of eczema
- Contact eczema: a localized reaction that includes redness, itching, and burning where the skin has come into contact with an allergen (an allergy-causing substance) or with an irritant such as an irritating acid, a cleaning agent, or other chemical
- Allergic contact eczema: a red, itchy, weepy reaction where the skin has come into contact with a substance that the immune system recognizes as foreign, such as poison ivy or certain preservatives in creams and lotions like Neosporin or Bacitracin
- Seborrheic eczema (also called seborrheic dermatitis or seborrhea): is a very common form of mild skin inflammation of unknown cause that presents as yellowish, oily, scaly patches of skin on the scalp, face, ears, and occasionally other parts of the body. Often this is also called dandruff in adults or “cradle cap” in infants.
- Nummular eczema: coin-shaped (round), isolated patches of irritated skin — most commonly on the arms, back, buttocks, and lower legs — that may be crusted, scaling, and extremely itchy
- Neurodermatitis: a very particular type of dermatitis where the person frequently picks at their skin, causing rashes. The underling cause may be a sensitivity or irritation which sets off a cascade of repeated itching and scratching cycles. It may be seen as scratch marks and pick marks on the skin. Sometimes scaly patches of skin on the head, lower legs, wrists, or forearms caused by a localized itch (such as an insect bite) may become intensely irritated when scratched.
- Stasis dermatitis: a skin irritation on the lower legs, generally related to circulatory problems and congestion of the leg veins. It may have a darker pigmentation, light-brown, or purplish-red discoloration from the congestion and back up of the blood in the leg veins. It’s sometimes seen more in legs with varicose veins.
- Dyshidrotic eczema: irritation of the skin on the palms of hands (mostly) and less commonly soles of the feet characterized by clear, very deep-seated blisters that itch and burn. It’s sometimes described as a “tapioca pudding”-like rash on the palms.
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.
While emotional factors and stress may in some cases exacerbate or initiate the condition, they do not seem to be a primary or underlying cause for the disorder. In the past, there was some thought that perhaps atopic dermatitis was entirely caused by an emotional 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 the symptoms of atopic dermatitis?
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. When things at home sort of quiet down, the itching seems to become more noticeable.
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.
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.
Is the sufferer’s skin type important?
Yes. Differences in the skin of people with atopic dermatitis may contribute to the symptoms of the disease. The epidermis, which is the outermost layer of skin, is divided into two parts: the inner part, which contains moist, living cells, and the outer part, which consists of dry, flattened, dead cells. Under normal conditions, the outer layer of skin acts as a barrier, keeping the rest of the skin from drying out and protecting other layers of skin from damage caused by irritants and infections. When this barrier is damaged or is naturally thin, irritants act more intensely on the skin.
The skin of a person with atopic dermatitis loses too much moisture from the epidermal layer. This 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
* Lichenification: thick, leathery skin resulting from constant scratching and rubbing
* Lichen simplex: refers to a thickened patch of raised skin that results from repeat rubbing and scratching of the same skin area
* Papules: small, raised bumps that may open when scratched, becoming crusty and infected
* Ichthyosis: dry, rectangular scales on the skin, commonly on the lower legs and shins
* Keratosis pilaris: small, rough bumps, generally on the face, upper arms, and thighs. These are also described as gooseflesh or chicken skin and may have a small coiled hair under each bump.
* Hyper linear palms: increased number of skin creases on the palms
* Urticaria: hives (red, raised bumps), often after exposure to an allergen, at the beginning of flares, or after exercise or a hot bath
* Cheilitis: inflammation of the skin on and around the lips
* Atopic pleat (Dennie-Morgan fold): an extra fold of skin that develops under the eye
* Dark circles under the eyes: may result from allergies and atopy
* Hyperpigmented eyelids: eyelids that have become darker in color from inflammation or hay fever
* Prurigo nodules also called “picker’s warts” are not really warts at all. These are small thickened bumps of skin caused by repeated picking of the same skin site.
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). The length of a remission varies, and it may last months or even years. In some children, the disease gets better for a long time only to come back at the onset of puberty when hormones, stress, and the use of irritating skin-care products or cosmetics may cause the condition to flare.
Although a number of people who developed atopic dermatitis as children also experience symptoms as adults, it is less common (but possible) 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 is atopic dermatitis diagnosed?
Atopic dermatitis is generally easily diagnosed based on a physical exam 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. While currently there may be no single specific laboratory test that says unequivocally “this is atopic dermatitis,” a skin biopsy (a sample of a small piece of skin that is sent to the lab for examination under the microscope) may be helpful to establish the diagnosis in harder cases. Additionally, gentle skin swabs (long cotton tip applicator or Q-tip) samples may be sent to the lab to exclude infections of the skin which may mimic atopic dermatitis.
Since itching tends to be the main common 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.
A valuable diagnostic tool is a thorough medical history, which provides important clues as to the possible causes of the patient’s ailment. The doctor may ask about all of the following: a family history of allergic disease, whether the patient also has diseases such as hay fever or asthma, exposure to irritants, sleep disturbances, any foods that seem to be related to skin flares, previous treatments for skin-related symptoms, use of steroids, and the effects of symptoms on schoolwork, career, or social life. Sometimes, it is necessary to do a biopsy of the skin or patch testing to determine if the skin’s immune system overreacts to certain chemicals or preservatives in skin creams. A preliminary diagnosis of atopic dermatitis can be made if the patient has three or more characteristics from each of two categories: major features and minor features. Some of these characteristics are listed in the box below.
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 as a medical history and careful observation of symptoms. However, they may occasionally help the doctor rule out or confirm a specific allergen that might be considered important in the diagnosis. Negative results on skin tests are reliable and may help rule out the possibility that certain substances are causing skin inflammation in the patient. However, positive skin scratch/prick test results are difficult to interpret in people with atopic dermatitis and are often inaccurate. In some cases, where the type of dermatitis is unclear, blood tests to check the level of eosinophils (a type of white blood cell) or IgE (an antibody whose levels are often high in atopic dermatitis) are helpful.
Major and minor features of atopic dermatitis
* Characteristic rash in locations typical of the disease (arm folds and behind knees)
* Chronic or repeatedly occurring symptoms
* Personal or family history of atopic disorders (eczema, hay fever, asthma)
Some minor features
* Early age of onset
* Dry, rough skin
* High levels of immunoglobulin E (IgE), an antibody, in the blood
* Hyper linear palms
* Keratosis pilaris
* Hand or foot dermatitis
* Cheilitis (dry or irritated lips)
* Nipple eczema
* Susceptibility to skin infection
* Positive allergy skin tests