Prevention of allergic contact dermatitis from nail varnishes and hardeners

Standard patch testing procedure cannot be used reliably in patients with acute widespread eczema. Cyclosporin A (CyA), 5 mg/kg/day for 10-15 days, enables such hyperreactive patients to be patch tested reliably. Some years ago, we began to treat patients with severe allergic contact dermatitis with CyA. We obtained rapid resolution of clinical signs, but observed no substantial variations in patch test response (I). We have since treated 33 patients and assessed 103 positive patch tests, performed before and after 1 month of CyA treatment. The intensity of reactions was quantified by colorimetry (CR-200, Minolta) with the "L a b" system. The parameter 'a' was evaluated at the test site and on surrounding healthy skin, the difference being used to measure reaction intensity. This study showed that true-positive reactions were not affected by cyclosporin: only weak reactions, often difficult to interpret, were suppressed. Quantitative patch testing has demonstrated that CyA inhibits the response to certain allergens at low concentrations (2). There is a threshold for the patch test response, which is raised by CyA therapy. However, in standard patch testing procedures, the threshold is high enough not to be affected by CyA treatment. Brief treatment with CyA, free from side-effects, allows patients with acute dermatitis, otherwise prone to false-positive reactions, to be patch tested. CyA also brings about rapid resolution of clinical manifestations, improving patient compliance with patch testing.