Reactivity to patch tests with nickel sulfate and fragrance mix in infants.

The pattern of patch test reactivity to nickel sulfate and fragrance mix was studied with respect to patch test performance, reproducibility and clinical relevance in a population of unselected infants followed prospectively from birth to 18 months of age. TRUE Testtrade mark patches with nickel sulfate in 3 concentrations, 200, 66 and 22 microg/cm(2), and fragrance mix 430 microg/cm(2) were used. A likely case of nickel sensitivity was defined as a reproducible positive reaction with at least homogeneous erythema and palpable infiltration occurring at least 2x and present at both the 12 and 18 months follow-up. 543 infants (268 girls and 275 boys) were tested at least 1x, 304 were tested at both 12 and 18 months. The prevalence of a reproducible positive reaction to nickel was 8.6% (20 girls and 6 boys). A transient positive reaction was observed in 111 children. Clinical relevance of nickel sensitivity was found in only 1 child. No reproducible positive reaction to fragrance mix was found. The high proportion of transient patch test reactivity to nickel sulfate 200 microg/cm(2) indicates that this standard concentration used for adults cannot be applied to infants. The interpretation of a single positive nickel patch test in infants must be assessed with caution and it is probably of non-specific or irritant nature.