Dr Robert Sidbury on risk factors, diagnosis of atopic dermatitis
A family history of atopic disease is a major risk factor for the development of atopic dermatitis, while diagnostic methods of skin biopsy and patch testing are used if the clinical diagnosis is in question, said Robert Sidbury, MD , MPH, chief of the Division of Dermatology at Seattle Children’s Hospital.
Can you talk about some common risk factors involved in the pathogenesis of atopic dermatitis and current diagnostic methods in young and old populations?
Risk factors for atopic dermatitis – classically one of the first questions asked of all patients, but particularly when it comes to atopic dermatitis – is whether there is a family history .
It’s not just a family history of atopic dermatitis or eczema—I’ll use these 2 terms synonymously for the purpose of this interview—not just a family history of eczema, but also a family history asthma, family history of food allergies, history of allergic rhinitis or hay fever. So that kind of flavor, that so-called atopic history is a big risk factor for atopic dermatitis, and really the first thing we ask.
In terms of diagnostic methods, the diagnosis of atopic dermatitis or eczema is typically clinical. We don’t usually do a skin biopsy, we don’t usually do a blood test, however, both of these modalities can be helpful if the diagnosis is in question. You would expect to see spongiosis in the biopsy which could support a diagnosis of atopic dermatitis if you were trying, for example, to distinguish it from psoriasis.
You might see elevated blood markers, including IgE [Immunoglobulin E]eosinophils, other things like that that aren’t remotely specific for atopic dermatitis, but that might support the diagnosis.
In terms of other actual diagnostic procedures when trying to separate atopic dermatitis from other things, one thing that comes up quite often is allergic contact dermatitis. It is seen more frequently in patients with atopic dermatitis, so there is a lot of overlap. You do a skin biopsy and the results are identical.
So that’s one place where the markers that we talked about before, the biopsy results aren’t going to help you. So there is a type of allergy test called a patch test, which can be extremely helpful in patients with atopic dermatitis when trying to rule out contact allergy. So there are certain tests that we do, although the diagnosis is generally clinical.