Sensitivity to thiourea in plan printing paper.

Two female patients with histories of contact dermatitis to nickel-containing jewelry (dime-thyiglyoxime test positive) failed to react to patch testing with 5 % nickel sulphate in yellow petrolatum. Further patch testing was performed with nickel sulphate 2.5 % and 5 % in water and with 2.5% in DMSO 50%, but no positive reactions were obtained. An intradermal test with a 1/10,000 dilution in water was also negative. Both patients were again patch tested with 10% nickel sulphate in yellow petrolatum, which resulted in ++ reactions after 48 and 96 hours.