Pediatric AD: Differential Diagnosis and Tools



Amy Paller, MD: Atopic dermatitis, no matter what age, is a clinical diagnosis. We look at the eczematous change, we look at the patterning, and we go from there to make the diagnosis of atopic dermatitis. We don't tend to biopsy unless we're trying to rule out something else. We don't tend to get laboratory tests, because high levels of IgE [immunoglobulin E] and eosinophilia, that's all part of the picture in so many children. So we don't use that to make the diagnosis. We do think about whether there might be alternative diagnoses. We as dermatologists do that very quickly because of the morphology of lesions.

But sometimes it's a little trickier and we might be thinking about, for example, could there be a concomitant contact dermatitis going on? Or this is an adult, are we sure this is not cutaneous T-cell lymphoma? Or maybe in a young infant, we may be wondering, in that baby who has what looks like atopic dermatitis but also has a lot of infections, could there be an immunodeficiency syndrome? So there is a differential that we consider. Of course, in babies, many have concomitant seborrheic dermatitis of the scalp. And that just goes along with the atopic dermatitis. This is largely a clinical diagnosis.

There is a differential diagnosis for atopic dermatitis in children, and there is a differential diagnosis for atopic dermatitis in adults. In adults, the one we worry the most about is cutaneous T-cell lymphoma. And there have been many patients who were thought to have atopic dermatitis and it turned out, after years of observation and perhaps biopsies, that this was the wrong diagnosis and it's really lymphoma.

In children, it's generally a bit more straightforward. In young babies, they often come in and may have seborrheic dermatitis, often concomitantly, or a seborrheic dermatitis that's very itchy and evolves into what is a more classic atopic dermatitis. But we can also, early on, think about differential diagnoses, such as immunodeficiency syndromes, in which we might suspect that because someone has what looks like typical atopic dermatitis but also has many infections. And those infections can be the clue that there's something more going on.

We certainly, at any age, need to be thinking about whether there might be some infection with some associated atopic dermatitis, whether there is a primary problem of atopic dermatitis with secondary infection or whether there is some kind of skin infection with secondary eczematization. And that can be something viral like molluscum, or it could be even bacterial. We also think about the possibility of having contact dermatitis. This can be at any age. And we need to be thinking about the fact that can look very much like atopic dermatitis.

It's an eczematous change. Sometimes it can be due to the emollients that someone's using and therefore can be very widespread. Sometimes it is due to something else that's touching certain areas. Particularly when we see dermatitis on the hands, feet, or on the face, we need to at least be thinking about the possibility, either of a concomitant or an alternative diagnosis, of contact dermatitis.

We also need to remember that, particularly children, can get scabies. And scabies is such an itchy disorder that often times we can see secondary eczematization. So someone who develops an itchy condition that can look eczematous and can be misdiagnosed as atopic dermatitis, especially if it's an older child and not an infant who develops it for a first time, we do need to think about the possibility of scabies and find out if anyone else in the household is affected, as well as the history of its development, and rule that out through finding evidence of the scabies mite.

In my own practice I do a lot of clinical trials. And in clinical trials, we do use some tools to measure atopic dermatitis. The diagnosis itself is really clinical. For the vast majority of children, there's no question what the diagnosis is. It's atopic dermatitis and we don't have to go any farther. We only use a diagnostic tool like biopsy if we're thinking about an alternative diagnosis and wanted to rule that out. And I will tell you, especially in pediatric practice, we don't do that very often. We might sometimes scrape for scabies, or we might consider patch testing to look for contact dermatitis. But again, in 95% of the cases, we wouldn't even be thinking about that or considering any alternative diagnosis.

Now, we do use some tools in practice to consider severity. In clinical trials, of course, we have many tools that are used. Like the EASI [Eczema Area and Severity Index] score, or SCORAD [Scoring Atopic Dermatitis tool], or the patient assessed POEM [Patient-Oriented Eczema Measure], or looking at itch NRS [Numerical Rating Scale] to try to grade the severity. But beyond that, in general practice, we really don't have the time to be doing all of those various tests. What we do basically is a global assessment where we decide someone is mild, or moderate, or severe.

We might go even a little bit farther to estimate the percentage of body surface area. And in fact, a new tool called the IGAxBSA [Investigator Global Assessment and body surface area], in which one takes into account both the global assessment and the extent of involvement, has been shown to correlate very well with EASI scores. So I'm starting to do more of that in my office, as well as assessing itch and sleep with at least a numerical value on all patients.

Transcript Edited for Clarity

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