Oral challenge with metal salts. (I). Vesicular patch-test-negative hand eczema.

202 patients, 68 males and 134 females, with patch-test-negative, symmetrical vesicular hand eczema were challenged orally in a controlled study with 2.5 mg nickel, 2.5 mg chromium and 1 mg cobalt given as salts of the respective metals. Initially a mixture of the 3 metal salts was given, and if this produced a flare of the eczema, the salts were administered individually at 1 week intervals. 55 patients reacted to the mixture of salts as well as to 1 or 2 of the individual salts. 3 other patients were challenged openly with nickel alone. Male patients reacted primarily to chromate and cobalt, while female patients more commonly reacted to nickel and cobalt. 56 patients were instructed to follow diets planned to reduce the daily intake of the respective metals. The dermatitis of 36 patients cleared or improved markedly after 1 month of dieting. Responses to a questionnaire sent to these 36 patients indicated that 28 of them had followed the prescribed diet rigorously or intermittently for at least a year, because they experienced recurrence of the dermatitis if they stopped dieting. 6 noted no long-term benefit and 2 did not respond.