Pediatric dermatology comes of age

New York - It's no coincidence that as physicians' understanding of pediatric dermatology deepens, the specialty itself matures as both a profession and a political entity.

"Atopic dermatitis (AD) is crucial to pediatric dermatology in that recent data has shown that in industrialized countries throughout the world, there's a prevalence of 20 percent or more of children affected with atopic eczema," says Lawrence F. Eichenfield, M.D., professor of pediatrics and dermatology, University of California, San Diego, School of Medicine and chief of pediatric and adolescent dermatology, Children's Hospital, San Diego. "We're now understanding eczema not just in terms of defining its features and the morphology of how it presents, but also in terms of a more rigorous understanding of some of the science behind the dermatitis."

Doctors also are learning more about parallels - in terms of both epidemiology and pathogenesis - between AD and other atopic diseases such as asthma (Eichenfield, Hanifin et al. Pediatrics. 2003; 111: 608-616).

By the same token, researchers now know more about the role of IgE, which is an important mediator of inflammation, and about the high-affinity IgE receptor, FC-epsilon receptor-1, which Dr. Eichenfield says is important in lesional eczema skin.

"The Langerhans and IDEC cells that have this receptor are overly efficient at presenting antigens," he explains. "Another new aspect of understanding contributed by pediatric dermatologists and pediatric allergists together has been the understanding of bacteria and other microbes that are stimulators of dermatitis. S. aureus is the classic example - it can be a super antigen stimulant, and there are high levels of bacteria colonization in eczematous skin."

Possible mechanisms for this colonization include problems with a set of endogenous antimicrobial peptides present in skin - human b-defensin 2 and LL-37.

"It's been shown (Ong PY et al. N Engl J Med. 2002; 347(15):1151-1160.) that in AD skin as compared to psoriasis there are lower levels of those two proteins, and that those two proteins naturally have antimicrobial effects on staph," Dr. Eichenfield says.

New treatments With new knowledge comes new treatments.

"We predict - and it's coming true - that there will be an evolution in therapy for AD as there has been in asthma due to a broadening set of both therapeutic agents and nonsteroidal agents which allows improved disease control in place of a reactive response to flares," Dr. Eichenfield says.

One issue that has commanded attention in recent years is safety concerns related to topical corticosteroids, with the U.S. Food and Drug Administration (FDA) taking a look at systemic absorption and its potential impact on normal adrenal gland function.

"While most dermatologists have not had observable clinical problems from topical corticosteroid use," he says, "this is presumably due to the intermittent use of these in attempts to decrease potential problems. The other big therapeutic advance has been topical calcineurin inhibitors, which have proven to be very successfully integrated into the care of AD patients of all ages. Topical tacrolimus and pimecrolimus have been rapidly accepted by the dermatologic community."

Individual responsibility With AD research reaching the point where new therapies are being integrated with traditional ones, Dr. Eichenfield believes dermatologists have a clear responsibility to do further research to determine optimal care models. In this area, ongoing studies are examining issues such as whether early treatment and continued control of AD can decrease the development of other allergic phenomena.