Oral challenge with metal salts. (II). Various types of eczema

299 patients with chronic dermatitis of obscure origin 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. Flares of the dermatitis were seen in 12 of 61 patients with patch-test-negative hyperkeratotic eczema, in 9 of 32 patients with patch-test-negative perianal eczema, and in 7 of 143 patients with various other patch-test-negative eczemas. In this latter group, flares were seen only among patients with nummular eczema or hand eczema. Among 34 patients with various positive patch tests not relevant to the current dermatitis, 3 with hand eczema experienced flares. Patients who reacted to oral challenge with the metal salt to which they had a positive patch test, included 3 of 9 with nickel allergy, 2 of 5 with cobalt allergy and 6 of 15 with chromate allergy. These patients were tested openly. Low metal diets were prescribed for 33 patients who had flares after oral challenge with specific metal salts. For 23 of these, the dermatitis cleared or improved markedly after following the diet for at least 4 weeks. Responses to a questionnaire sent to the 23 patients indicated that 16 had followed the prescribed diet rigorously or intermittently for at least a year.