FS01.3 Disperse (yes), orange (yes), 3 (no): what do we test in textile dye dermatitis?

  Patients sensitized to para‐phenylenediamine (PPD) have a high degree of patch test reactivity to Disperse Orange 3 (DO3), and a lesser one to Disperse Red 1 and Red 17. Two successive patients positive to PPD, Disperse Red 1 and 17, negative to DO3 were real eye‐openers for our considerations about purity of our current allergen DO3. Materials and methods:  We realized comparative thin‐layer chromatography (TLC), with DO3 from Chemotechnique®(DO3‐Chem) and Trolab®(both extracted from petrolatum), and “pure” DO3 from two chemical providers. TLC clearly indicated that DO3‐Chem was not DO3. HPLC analysis with pure DO3 from Chemotechnique® and comparison of structures by NMR with samples of DO3, revealed that DO3‐Chem was Disperse Orange 31 (DO31). In addition, signals through the GERDA network allowed the collection of test materials and observations. Among other members, only 2 used DO3‐Chem (from 2 different batches) that was DO31 too, according to TLC Results: According to their data, they observed no or a lower reactivity to DO3 than expected (4 patients DO3‐Chem + among 23 PPD+ e.g.). Finally, the error was proved to be due to the provider of the dye to Chemotechnique®, who likely deleted the 1 of Disperse Orange 31 on his packaging. Discussion:  Chemical structure of DO31 indicates a possible in vivo hydrolysis into nitroaniline and a second compound, a substituted PPD derivative that clearly does not frequently react in PPD positive patients. Like drugs, patch tests are submitted to post‐commercialization controls. In addition to allergens providers who should enhance their quality controls, dermato‐allergologists have to be vigilant, and must active networks when they observe a rare bird.