Patch Testing With an Extended Metal Allergen Series at the Massachusetts General Hospital (2006-2017)

Reports of patch test data with an extended metal series that includes rare metals are limited.

The aims of the study were to analyze and report patch testing results from an extended metal series, examine associations with sex and age, and highlight concomitant metal reactions.

This study is a retrospective review of 150 patients referred for suspected metal allergy from January 1, 2007, to December 31, 2016.

The most common indications for evaluation referral were those having symptoms after implantation of a metal device (55.3%) and those with a history and concern of metal allergy before implantation of a metal device (22.0%). One or more positive patch test reactions were observed in 87 patients (58.0%). Metals with the highest frequencies were nickel sulfate 2.5% (26.2%), gold sodium thiosulfate 0.5% (23.0%), gold sodium thiosulfate 2.0% (20.7%), palladium chloride 2.0% (19.6%), cobalt chloride 1.0% (12.0%), and manganese chloride 2.0% (10.1%). Of the 45 metals tested, 15 caused no patch test reactions. Female patients were more likely to be sensitized to nickel, gold, and palladium (P < 0.05). Younger patients (≤40 years) had higher reaction rates to nickel, mercury, palladium, and cobalt. Concomitant reactions of the top metals (nickel, palladium, gold, and cobalt) were statistically associated bidirectionally (P < 0.05), except for cobalt and gold.

Allergy to metals, including those not included in standard series, may be more prevalent than previously suspected. Results may help guide future testing for suspected metal allergy, although future studies are warranted.