How Is Atopic Dermatitis Diagnosed?
Reviewed by: HU Medical Review Board | June 2017 | Last updated: October 2020
A diagnosis of atopic dermatitis (AD) is made based on features seen on a physical exam. A general practitioner, like a pediatrician or other primary care provider, may make the diagnosis, or a dermatologist who specializes in skin conditions, may provide the diagnosis.
Diagnostic criteria for atopic dermatitis
AD is diagnosed based on the symptoms the individual is experiencing, as well as their history of symptoms. AD has several symptoms, and different people can have variations in which symptoms they experience. Several sets of formal diagnostic criteria for AD exist, and the American Academy of Dermatology (AAD) has provided diagnostic guidelines to help doctors properly diagnose AD.1
The AAD diagnostic guidelines outline essential features that must be present to make a diagnosis of AD, as well as important and associated features that may exist. Finally, exclusionary conditions are noted in the guidelines to differentiate AD from other conditions.1
Stages of atopic dermatitis
AD can show up in one of three clinical stages:
- Acute AD appears with vesicles or blisters, weepy skin, and crusting
- Subacute AD appears with dry, scaly, red papules and plaques
- Chronic AD appears with lichenification, areas of thickened skin from repeated scratching2
Common symptoms of atopic dermatitis
As a relapsing skin condition, AD can cause a number of symptoms, including:
- Dry, scaly skin
- Changes in skin color
- Weepy sores
- Blisters or vesicles
- Thickened skin3,4
Age-specific patterns of atopic dermatitis
AD is most commonly diagnosed in children before two years of age, with only 10% of cases diagnosed after age five.2 AD appears differently depending on the age of the person affected.
The age-specific patterns of AD have been identified as:
- In infants and young children, the rash shows up on the face, neck and extensor (outer surfaces of the limbs) surfaces
- In older children, AD frequently appears as a rash on the inside creases of the elbows or knees (flexural surfaces), the neck, wrists, ankles, and/or the crease between the buttocks and the thighs
- In adults, the rash appears as a rash on the inner creases of the elbows or knees, and/or the nape of the neck1,3
Is there a test for atopic dermatitis?
There are no known or reliable biomarkers – for example, a measurable lab test – that can distinguish AD from other conditions, so most diagnoses are made through observation of the signs and symptoms, as well as a patient history. In unclear cases, a biopsy may be performed on the affected skin, which can show microscopic evidence of AD and help to distinguish the diagnosis of AD from other conditions.
Elevated IgE levels and atopic dermatitis
Some people with AD have an elevated total or allergen-specific immunoglobulin E (IgE) level. Immunoglobulin is a type of protein that is part of the immune system and that acts as an antibody to attach and destroy foreign substances. There are five different types of immunoglobulin, and the IgE protein is found in increased levels in people with allergies.
IgE causes the body to release histamine when it comes into contact with an allergen. However, about 20% of people with AD do not have an elevated IgE level, and having an elevated IgE level does not alone make a diagnosis of AD either.1,5,6
People with AD have a higher rate of environmental and food allergies, and doctors assess for these conditions during a patient history. Those patients that have symptoms of allergies or whose AD is persistent or difficult to treat may receive additional testing for allergens. Tests for allergens include skin prick testing and blood tests.7