Patch Testing Identifies Allergens Responsible for Contact Dermatitis

By Reuters Staff

December 06, 2019

NEW YORK (Reuters Health) - Patch testing is useful for identifying allergens responsible for facial dermatitis in male patients and for anogenital dermatitis, according to two analyses of data from the North American Contact Dermatitis Group (NACDG).

In one study, Dr. Erin Warshaw of Minneapolis Veterans Affairs Medical Center and the University of Minnesota Medical School, in Minneapolis, and colleagues used data on more than 50,000 men who underwent patch testing to compare characteristics of those with and without facial dermatitis.

Overall, 8.0% of men tested had facial dermatitis, with an increase from 5.6% in 1994-1996 to 10.6% in 2015-2016.

Compared with men without facial dermatitis, men with facial dermatitis were more likely to react to dimethylaminopropylamine (a surfactant) or paraphenylenediamine (a constituent of hair/mustache/beard/eyebrows dye) and less likely to have clinically relevant reactions to traditional allergenic preservatives.

Top sources of allergens included personal care products and topical medications, while top sources of irritants included personal-care products and industrial chemicals.

"It is important to inquire directly about hair dye and facial personal care products," the authors conclude. "Facial protection may help occupationally related facial dermatitis. In cases of severe, worsening, or refractory male facial dermatitis, comprehensive patch testing may be necessary in this new metrosexual era."

In the other study, Dr. Warshaw and colleagues used data from more than 28,000 patients who underwent patch testing to compare characteristics of those with and without anogenital dermatitis.

"Contact dermatitis in the anogenital area is associated with sleep disturbance and dyspareunia and can profoundly affect quality of life," they write in JAMA Dermatology, where both studies are published. "The literature on anogenital contact dermatitis and culprit allergens is limited. The last large-scale study on common, relevant allergens in patients with anogenital dermatitis was published in 2008."

Allergens that were more common among the 449 patients in the anogenital-dermatitis group included the topical anesthetics dibucaine and benzocaine and the topical corticosteroids triamcinolone acetonide and desoximetasone.

Among the 152 patients with allergic contact dermatitis as their only diagnosis and with anogenital involvement only, the most common allergens were preservatives, fragrances, medications, emulsifiers, corticosteroids, nickel sulfate and surfactants. The most common allergen sources were personal-care products, medications, food products, and clothing.

"It is important for patients with anogenital involvement who are suspected of having allergic contact dermatitis to undergo patch testing because more than half will likely have one or more currently relevant allergic reactions," the authors conclude.

"Accurately diagnosing the cause of allergic contact dermatitis and providing effective avoidance strategies can greatly improve patients' quality of life," writes Dr. Susan T. Nedorost from Case Western Reserve University, in Cleveland, Ohio, in a linked editorial. "Identifying an allergen allows for a cure without drugs, without surgery, and without the need for any follow-up appointments."

"Dermatologists should be aware of all the potential allergens for different patterns of contact dermatitis when deciding which patients to test and for which allergens," she says. "Patch testing must be comprehensive to be of value, such that there is no 'magic number' of patch tests that are appropriate for any given patient. Insurers need to understand this when covering patch test procedures."

"The better strategy is to minimize the use of any product that is not necessary," Dr. Nedorost. "Including the risk of allergic contact dermatitis in any product making a 'skin health' claim would be a great service to consumers and to dermatologists who appreciate the relative lack of knowledge of this condition in the patient population."

The corresponding authors on the reports did not respond to requests for comments.

SOURCE: https://bit.ly/2YhXatU, https://bit.ly/366CJTo and https://bit.ly/2RnCHmf JAMA Dermatology, online November 27, 2019.

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