Immunological contact urticaria caused by dimethylfumarate

Dimethyl fumarate (DMF) is a well-known contact irritant and sensitizer that has been responsible for severe contact dermatitis [1-3]. Up to now, immediate hypersensitivity caused by DMF has never been reported. A 30-year-old non-atopic woman with itchy contact urticaria (CU) on the internal surfaces of the lower limbs is reported. This immediate reaction appeared a few minutes after she started wearing a pair of skinny jeans. No respiratory or gastrointestinal tract signs were referred. The patient reported two other episodes of CU on her lower limbs. Patch tests were performed with the SIDAPA baseline series, a textile series (containing DMF 0.01% pet.), and dry and moistened pieces of the jeans. At the 20-min patch test reading, a wheal and flare reaction to DMF was observed. A prick test with DMF (0.01% in saline) was carried out. An immediate positive reaction was observed at 20 min. Chemical–toxicological analysis (gas chromatography - GC) showed DMF in the samples of jeans. Delayed hypersensitivity to DMF is well known and EU Member States have banned the importation and marketing of products containing DMF used to inhibit mould growth in furniture, footwear and, more recently, clothes. However, immediate CU caused by DMF is rare.We underline that among IgE-mediated clothing CU cases this is the first one caused by DMF as shown by a positive immediate occluded patch test result and a positive prick test reaction with DMF.