Consumer Information Center Atopic DermatitisDiagnosing

Atopic dermatitis is more common in infancy and childhood. It affects each child differently, in terms of both 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 knees and elbows may also be affected. An infant with atopic dermatitis may be restless and irritable because of the itching and discomfort of the disease. Many infants get better 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 the skin around the mouth. Severe cases of atopic dermatitis may affect growth, and the child may be shorter than average.

The disease may go into remission. 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 disease to flare.

Although a number of people who developed atopic dermatitis as children also experience symptoms as adults, it is unusual (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 to a more restricted form. 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 atopic dermatitis 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 or 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.

Currently, there is no test to diagnose atopic dermatitis and no single symptom or feature used to identify the disease. Each patient experiences a unique combination of symptoms, and the symptoms and severity of the disease may vary over time. The doctor will base his or her diagnosis on the symptoms the patient experiences 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.

Several tools help the doctor better understand a patient’s symptoms and their possible causes. The most valuable diagnostic tool is a thorough medical history, which provides important clues. The doctor may ask about family history of allergic disease; whether the patient also has diseases such as hay fever or asthma; and about 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 effect of symptoms on schoolwork, career, or social life. Sometimes it is necessary to do a biopsy of the skin or patch testing to see if the skin 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 features from each of two categories: major features and minor features.

Skin scratch/prick tests (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 the diagnosis of 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 diagnosis. Although negative results on skin tests are reliable and may help rule out the possibility that certain substances cause skin inflammation in the patient, positive skin scratch/prick test results are difficult to interpret in people with atopic dermatitis and are often inaccurate. Blood tests, including measurements of certain antibodies to allergens, are not recommended in most cases because they have a high rate of false positives and are expensive. 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.