CD16 Tackling shinpad contact dermatitis to acetophenone azine with generalization: autosensitization or presence in clothing?

Abstract We present the case of a 12-year-old boy with atopic eczema, who had a 6-month history of a recurrent dermatitis on his anterior shins. He wore shinpads weekly while playing football. The dermatitis would also significantly affect his trunk and buttocks. He was tested to our baseline, anti-infective, excipient, rubber, cosmetic, fragrance, textile and plastic additive series, along with his shinpad material. Acetophenone azine (AA) is included in our plastic series at 0.1% dilution in petrolatum. He developed a strong reaction to AA and his shinpad by 96 h. He also reacted to limonene hydroperoxide (0.2% and 0.3% in petrolatum). Shinpad dermatitis secondary to the emerging contact allergen AA was first reported in 2016. AA appears to develop during the manufacture of ethylene vinyl acetate (EVA). EVA is a thermoplastic copoly­mer used in foam linings of shinpads and footwear. AA is postulated to be present in higher concentrations in shinpads than in footwear. EVA is also reported to be present in protective clothing as it is flexible and impact resistant. To our knowledge, there are fewer than 30 cases in the literature. It has predominantly affected male children wearing shinpads for playing sports, in particular football. The dermatitis spreads beyond the sites of contact in most patients, in at least eight out of 11 cases (73%). The preponderance in sex, age and generalization is unclear. Our patient’s parents were unable to source an EVA-free shinpad. He continued to experience persistent dermatitis on the shins and trunk months later, despite using ‘Dokpav Shinguard Sock Sleeves’ as a protective barrier. However, this could be insufficient to prevent skin contact from AA. Patch testing was repeated with a sample of his football jersey (100% polyester) and the sock sleeves (nylon) soaked in water. There was a negative reaction to the jersey, but interestingly a positive reaction to the sock sleeves after 96 h. EVA has been reported to be added to strengthen nylon 6, a synthetic durable textile used in clothing. In conclusion, we hypothesize that EVA, and consequently AA, may contribute to generalized reactions in patients with AA-induced shin dermatitis due to its presence in clothing. This challenges the current assumption that generalization is purely an autosensitization phenomenon. We plan to analyse the sock sleeves and potentially football kits using high-performance liquid chromatography to confirm the presence of AA. Furthermore, we identified an EVA-free shinpad option from Orthotics UK, which replaces EVA foam with microfibre, offering a potential alternative for patients with AA allergy.