An anatomo‐clinical study of delayed skin allergic reactions to nickel following intradermal injections of lidocaïne with a Dermo‐Jet

10 women allergic to nickel developed skin reactions at injection sites with a Dermo-Jet (Krantz model) of (a) 2% lidocaine solution and (b) 0.9% saline solution. 10 women (age-matched) not allergic to nickel were selected as controls and submitted to the same injections; they had no positive reactions. Various controls (including injections with a needle and patch tests) were made in both groups. Nickel was leached into fluids from the metallic internal parts of the Dermo-Jet. The positive reactions were allergic and due to nickel. Histology showed changes of an allergic contact dermatitis with particular features, probably due to the intradermal injection of nickel. Some practical implications regarding the quality of medical instruments are discussed.