Optimizing Treatment of Pediatric Atopic Dermatitis - Episode 3
Lawrence Eichenfield, MD: Let’s discuss the pathophysiology of atopic dermatitis [AD] and the evolution of our knowledge about it. There have certainly been a lot of changes in our understanding. I’m going to tee it off with a question: Are there differences in the pathophysiology between adults and kids? I’ll answer to start, yes and no. We’ve married the different perspectives on atopic dermatitis, inside job or outside job. What do I mean by that? We went through a decade of really good work showing that there’s barrier dysfunction in atopic dermatitis; that it’s compromised in drier skin, more open skin; that this is something that can be seen in very early life; and that this is a setup for sensitization through the skin and to set up this inflammation.
There are other factors, probably, in terms of risk factors that influence the immunology within the skin, which of course manifests our rashes. We know that when you have a lot of inflammation, it further compromises the skin barrier. When we have compromised skin barrier, that influences inflammation as well. When we use anti-inflammatories, either topical or systemic, we get improvement of barrier function as well as decreased inflammation. I haven’t even mentioned microbiome, which travels along with both barrier dysfunction and inflammation.
Lastly, I want to mention that there has been some elegant work that’s looked on the immunology of pediatric atopic dermatitis compared with adults. The Th2 influence of immunology is there, but there’s also a Th17, a Th22. Th22 relates to a lot of epidermal hyperplasia as well, and there’s less of a Th1 access in the adults. We tend to see a lot more Th1, which in our heads we’ve said is more associated with chronic disease. At least in kids under 5 years, in studies done by Amy Paller and Emma Guttman and colleagues, it looked as though there was less of a Th1 access. How this influence treatment or responses to either systemic or topical treatments isn’t known, but it’s an intriguing observation.
Why don’t we discuss presentation and severity of AD and also the differences in kids versus adolescents and adults. Elaine, do you want to discuss that, as well as some of the challenges faced by kids and teens from their eczema?
Elaine Siegfried, MD: Classically, we’re all familiar with the variation and distribution in infants. It is said to involve their face a little more, spare their diaper area, and involve their extensor extremities, where you’ve got more of that classic antecubital, popliteal fossa distribution as you get older. I’m a stickler for that distribution because I really think that you can clinically separate atopic dermatitis from some other conditions like contact dermatitis or even psoriasis-eczema overlap. It’s important to pay attention to some of that distribution. Although when you’ve got contact dermatitis complicating things, it muddies the waters a little. The other thing I wanted to briefly mention is about the difference in presentation in children with skin of color. It’s something we’re all becoming increasingly aware of, but in skin of color you really can’t appreciate the erythema as much. You get a lot more lichenification and dyspigmentation along with that, and those are not only important to recognize as a disease but really bothersome to patients who are affected. It’s important to recognize and discuss that.
Lawrence Eichenfield, MD: How about body surface area and severity in kids compared with adults? Anyone want to take that on?
Elaine Siegfried, MD: We know now that at least the inflammatory response and some of the biomarkers you see in atopic dermatitis, even in non-clinically involved skin, are really clinically involved, as opposed to other diseases like psoriasis. But the individual severity, and the persistence, and the degree of flare are all parameters that we’ve got to take into consideration.
Lawrence Eichenfield, MD: But if you look at some of our young kids who have very high body surface area and you score them on an IgA and investigative global study, they may not have severe qualities to their disease. But for them to have 15%, 20%, 25% body surface area is not uncommon. They could have a lot of mild eczema, which qualifies a lot by body surface area. That tends to be a little less different in adults, who can have very low body surface area but profound disease, especially in hand eczema and facial dermatitis, where it can be really debilitating, localized eczema. So that’s a little different.
Elaine Siegfried, MD: That complicates doing clinical trials and measuring outcomes as much as anything, but for patients of course it complicates topical therapy to have widespread body surface area that needs treating, and then even recognizing what’s involved and what’s not involved. Parents of children with widespread eczema tend to ignore the mild parts and just put the topical medication on the more moderate to severe parts when really you need to treat all of it.
Lawrence Eichenfield, MD: One of the really interesting things is mild disease and young kids. Fred, do you want to weigh in on that? There are some younger kids who can be managed only with intermittent topicals. Is that your sense?
Fred Ghali, MD:I totally agree. A lot of our milder patients have just minimal erythema and maybe minimal pruritus, a good regimen of basic skin care cleaners and regular use of moisturizers is important. When they need treatment or if they seek treatment, oftentimes they’re going to use an over-the-counter, low-potency topical steroid. For those mild patients, that’s the first step.
Transcript Edited for Clarity