Atopic Dermatitis (cont.)

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How is atopic dermatitis diagnosed?

Atopic dermatitis is generally 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.

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 white blood cells of allergy (eosinophils counts) in the blood and/or and elevated serum IgE levels. These tests can support the diagnosis of atopic dermatitis. 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.

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.

Major and minor features of atopic dermatitis

Major features

  • Itching
  • 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
  • Ichthyosis
  • Hyper linear palms
  • Keratosis pilaris
  • Hand or foot dermatitis
  • Cheilitis (dry or irritated lips)
  • Nipple eczema
  • Susceptibility to skin infection
  • Positive allergy skin tests
Medically Reviewed by a Doctor on 8/3/2012

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