Nickel-elicited systemic contact dermatitis - A report of 20 cases and a review of the literature

20 patients with systemic contact dermatitis due to nickel are described. Of these patients, 15 were female and 5 were male. Their mean age was 24.8 years (16-51 years). All had experienced contact dermatitis in the umbilical area due to continual contact with metal belt-buckles or buttons. Then, with long- or short-term aggravation of such periumbilical dermatitis, commonly in summer, lesions spread to other sites such as the side of the neck, the flexures of the extremities, etc. All patients showed a positive patch test to nickel sulphate (2.5% in petrolatum) and the dimethylglyoxime test demonstrated the presence of free nickel on metal buttons or belt-buckles. Punch biopsies performed in 7 patients showed subacute dermatitis. After avoidance of continual exposure to objects containing nickel and foods rich in nickel, as well as treatment with oral antihistamines and topical corticosteroids, all patients improved or cleared. It has been reported that nickel can cause systemic contact dermatitis by some internal systemic route, such as oral intake, transfusion, inhalation, implantation of metal medical devices, etc. In our patients, we found that continual local skin contact could also elicit systemic contact dermatitis.