acetophenone azine, a recently discovered allergen found in shin pads and footwear containing foam (Dermatitis. 2021. 32(1):5-9)

Christen Mowad, MD

The American Contact Dermatitis Society has announced the allergen of the year for 2021: acetophenone azine, a recently discovered allergen found in shin pads and footwear containing foam (Dermatitis. 2021. 32(1):5-9). Several cases have been described in patients presenting with significant allergy to shin pads. One of these first patients identified, tested positive only to the ethyl vinyl acetate foam used in the shin guard. Through collaboration between dermatology and chemists, high-performance liquid chromatography was performed, and the allergen was identified as acetophenone azine. Other cases of patients wearing shin pads, as well as footwear, have been reported in the literature. The dermatitis can present either under the shin pads as an exuberant dermatitis or on the feet if secondary to footwear. It is believed that sweat and occlusion enhance the reaction under the shin pad. Occasionally, widespread dissemination has been seen. Most of the patients reported are children or teenagers and, to date, are primarily in Europe.

Acetophenone azine is also known as 1-phenylethan-1-one (1-pheynlethylidene), hydrazone, or methylphenyl ketazine. This chemical is typically used as an intermediate in organic synthesis and it is thought that the chemical is a manufacturing byproduct. This chemical is not commercially available at this time. If testing is done, the chemical must be obtained from a distributor of chemical products. The best concentration identified at this time is acetophenone azine 0.1% in acetone or petrolatum. The authors of the article believe that many current cases of dermatitis are being attributed to irritant contact dermatitis because this allergen is not yet available for testing and as this allergen becomes more readily available, many other sources of the allergen will be identified.