Investigators find new triggers for contact dermatitis

Key Points

Of the two forms of contact dermatitis, irritant and allergic, the former is the more common. However, allergic contact dermatitis (ACD) is the variety most commonly occurring in adults, although it can occur in children, as well.

Apra Sood, M.D., associate staff member in the Cleveland Clinic's department of dermatology, says ACD is caused by sensitivity to some specific substance that comes into contact with the skin, and that a prior exposure is necessary before the dermatitis is seen clinically.

"A sensitized person may also react to chemically similar allergens, a phenomenon known as cross-sensitization. Common causes of ACD are nickel, balsam of Peru, topical antibiotics such as neomycin, formaldehyde and formaldehyde releasers and rubber chemicals," Dr. Sood says.

She says the capacity for sensitization varies from person to person.

Depending on the allergen, she says, the clinical picture can vary from a severe blistering dermatitis, as seen with poison ivy, to mild intolerance and itching, as seen with allergy to certain cosmetics.

Allergen uptake

"Recent basic research in this field includes studies involving allergen uptake and processing in skin dendritic cells and allergen-induced changes in gene expression," she says.

"The cells are treated with various chemicals and studied for gene expression, as well as changes in cytokine expression. This helps in identifying the potential of chemicals to produce allergic contact dermatitis and in understanding the pathogenesis of the disease more accurately," Dr. Sood says.

Epidemiological studies also are critical to identifying new allergens and exposures.

"A recent multi-center study from Europe has identified new fragrance allergens that were not being routinely tested," she says. "A fragrance mix with six new ingredients has been now added to the standard patch-testing tray of the North American Contact Dermatitis Group (NACDG)."

Patch testing remains the gold standard for identifying and diagnosing ACD, Dr. Sood says.

Details of past treatments and response to treatment should be recorded, as well.

Treatments

According to Dr. Sood, currently popular, effective management and treatment of ACD includes determining possible relevance of positive patch tests, and having discussions with patients to work out strategies for avoiding contact with the allergens.

"The contact allergen replacement data (CARD) available to the members of the American Contact Dermatitis Society is a valuable resource for physicians. It enables them to provide patients with alternatives they can safely use," she says.

"And although avoidance is the mainstay of treatment, topical corticosteroids are often needed to control the symptoms. Short-term use of potent topical corticosteroids is a preferred treatment, and nonsteroidal topical immunomodulators, such as tacrolimus or pimecrolimus, can also be beneficial," Dr. Sood says.

Very severe ACD cases may require a short course of oral corticosteroids and immunosuppressive therapy such as cyclosporine, she says.

Continuing challenges

Even given the recent and ongoing research into causes and new treatments for ACD, Dr. Sood emphasizes that researchers will be challenged to keep pace with the ailment into the future.

"New chemicals are constantly being introduced into our environment, and some of these can be potential allergens," she says.

Dr. Sood cautions that even though ACD most commonly afflicts adults, it can develop in children and that they should be patch-tested if clinically indicated.