Contact dermatitis to a desk mat without an antimicrobial coating

Abstract

While a number of patients with contact dermatitis to antimicrobial coatings of desk mats have been reported recently, we encountered a patient with contact dermatitis to a desk mat without an antimicrobial coating. A 48-year-old woman, an office worker, had suffered from erythematous lesions on her bilateral forearms and hands for 8 years. Her skin lesions were present periodically from the end of June to November in every year. Her forearms were exposed during this period because she usually wore short-sleeved shirts. Since she used a desk mat in her daily work, we considered the possibility of contact dermatitis to a desk mat Patch testing with her own desk mat, 'as is', showed a positive reaction. The desk mat was not treated with an antimicrobial coating and contained 5 ingredients: Polyvinyl chloride, plasticizer (dioctyl phthalate), epoxidized linseed-oil, methylene-bis-stearylamide, and a "metallic soap stabilizer," according to the manufacturer. The company provided us with these ingredients. Although 4 ingredients were exactly identical to those used in the desk mat the metallic soap stabilizer was substituted with similar material because production of this stabilizer was discontinued. The provided stabilizer consisted of barium and zinc and has a molecular structure that is close to that of the original one. We performed a patch tests with these 5 ingredients, and only the metallic soap stabilizer produced an allergic reaction. Patch testing with the stabilizer in 7 control subjects was negative. Based on these results, we concluded that her skin lesion was contact dermatitis due to the stabilizer contained in the desk mat that was not treated with an antimicrobial coating. Our review of the previous literature uncovered no report of such cases. This case demonstrates the risk of contact sensitization to stabilizers that are widely used in daily life.