Contact sensitivity to nickel and other metals in jewelry reactors

Background: Many patients who give a history of a dermatitis reaction to je welry or metal contact with skin are negative to metals on standard patch t esting. Some may be showing false-negative reactions. Objective: Our purpose was to determine whether patients with a history of jewelry reactions but whose standard patch tests were negative have a false -negative reaction or are allergic to metals other than nickel, cobalt, or chromium. Methods: Four hundred forty-nine patients were studied who gave a history o f reacting to jewelry or metal. Of these, 210 were tested to the metals in the European standard series (ie, nickel, cobalt, and chromate), and 239 we re tested to the metals in the standard series and to an extended metal ser ies of palladium, gold, platinum, a second nickel salt, and a nickel/cobalt mixture. These were compared with 752 patients who did not give a history of jewelry or metal reactions, of which 50, besides the standard series, we re also treated with the additional metal series. Results: A higher proportion of jewelry-reactive patients tested with the e xtended series reacted to nickel (and to other metals) than those who were tested only with the European standard series: (61% vs 38%; P < .0001). The use of the extended series showed that palladium allergy was common, prese nt in 34% of nickel-allergic patients, but it always occurred with nickel s ensitivity. Gold allergy coexisted with nickel sensitivity in 10% of cases. Testing simultaneously with separate patches containing 5% nickel sulfate and 5% nickel chloride showed a concordance of 71% in identified nickel-sen sitive patients. Nickel sulfate was more likely than nickel chloride to det ect nickel sensitivity The use of a combined preparation of 2.5% nickel sul fate and 0.5% cobalt chloride in petrolatum revealed only 3 jewelry-reactiv e patients who were negative to other metals. There was a slightly higher p roportion of atopic patients in the patch test-negative jewelry reactors gr oup than in the positive group; however, the difference was not significant and it was not sufficient to account for the negative findings. Conclusion: Some jewelry reactors who had negative patch tests are likely t o be subclinically allergic to nickel. We suggest that the higher number of antigens, or perhaps the larger nickel load, in the extended metal series, resulted in a larger proportion of patients reacting. To better demonstrat e nickel allergy in jewelry reactors, patients should be patch tested to a metal series that contains palladium and gold salts and perhaps a second ni ckel patch because these may reveal the presence of nickel sensitivity when standard patch tests would otherwise have been negative.