Urticaire chronique par allergie alimentaire au nickel

Abstract

Allergic contact dermatitis due to nickel is a common and well-known disorder, mediated by T-lymphocytes. The existence of systemic manifestations, especially urticaria due to the nickel contained in food remains a matter of strong debate. The aim of the present study was to demonstrate by a positive placebo-controlled oral challenge test (PCOCT) followed by the disappearance of symptoms after a low nickel diet the existence of true urticaria triggered by nickel contained in food, resulting in chronic urticaria. We studied 21 patients suffering from chronic idiopathic urticaria; all of them had a positive nickel sulfate patch test. A PCOCT with oral nickel pidolate (cumulative dose, 6.9 mg nickel) was performed in each subject. Fifteen of the 21 patients had a positive PCOCT. We observed three different types of response: one immediate response, nine intermediate responses and five delayed responses. A low nickel diet was effective in 11 patients, and drug treatment was stopped completely in nine of them. In addition, removal of a metallic dental prosthesis plus a nickel-avoidance diet in four cases led to a successful result in two of them. The PCOCT was negative in the six other patients; cutaneous itching or laryngeal discomfort without urticaria occurred after the first dose of placebo in two of them. Given these results, we recommend that a diagnosis of nickel-induced food allergy be considered in patients with chronic urticaria if the etiology remains unknown.