RESUMEN
BACKGROUND: Metal allergies are the most frequent causes of allergic contact dermatitis. Although the use of palladium is increasing, it is not included in any baseline series. OBJECTIVE: To assess the prevalence of hypersensitivity to palladium and to describe the clinical and demographic characteristics of patients who are sensitized to palladium dichloride (PdCl2 ). METHODS: A single-centre, retrospective study of 15 years of patch testing with the Spanish baseline series supplemented with PdCl2 2% pet. was performed. We collected clinical and demographic data and data on co-sensitization among the metals studied, and we compared patients who were sensitized to palladium, with or without co-sensitization to nickel, with the rest of the study population. RESULTS: Among the 3678 included patients, 730 (19.9%) were sensitized to nickel sulfate. The prevalence of sensitization to PdCl2 (n = 316, 8.6%) was higher than the prevalence of sensitization to potassium dichromate (n = 240, 6.5%) and similar to the prevalence of sensitization to cobalt chloride (n = 353, 9.6%). Only 26 (8.2%) of the patients sensitized to palladium were not co-sensitized to nickel. The percentage of men and patients aged ≥40 years was higher in this subgroup than in the patients with nickel co-sensitization. CONCLUSIONS: Given the high prevalence of hypersensitivity to PdCl2 , this metal salt should be included in the Spanish baseline series, notwithstanding the frequency of co-sensitization to nickel.