Systemic nickel allergy presenting as papuloerythroderma-like eruptions.

An 82-year-old woman had had pruritic papules on her entire body for 4 years. Her medical history included hypertension controlled with cilnidipine. On examination, there were numer ous red-brown lichenoid papules on her trunk and extremities. The papules tended to aggregate or coalesce to form diffuse erythematous plaques with sparing flexors, mimicking papuloerythroderma (Fig. 1). Laboratory data revealed elevated levels of blood eosinophils (1204/μl) and lactate dehydrogenase (354 U/l), but no other abnormal findings. Histologically, lichenoid papules showed irregular acanthosis with hyperkeratosis. There was a cellular infiltrate comprising lymphocytes and eosinophils in the upper dermis (Fig. 2). Extensive examinations, including serum tumour markers, computed tomography and fiberscope examination of the gastrointestinal tract, did not reveal any evidence of internal malignancy. The condition had been resistant to topical corticosteroids prior to admission, but the skin lesions improved after external application of petrolatum and without cessation of cilnidipine. Lymphocyte stimulation test and patch-testing for cilnidipine (10% and 20% in petrolatum) were negative. She did not have a history of allergic reactions to metals. However, patch-testing for metals revealed positive reactions for NiSO4 (5% aq) and K2Cr2O7 (0.5% aq) at 48 h, 72 h and 7 days. Oral challenge test with 12 mg NiSO4·6H2O (2 mg Ni) (1, 2) induced diffuse erythema with pruritus on her trunk and extremities, but similar effects were not seen with 7.5 mg K2CrO4 (2.5 mg Cr) or placebo control (NaCl 10 mg) (Fig. 3); the reaction peaked at 2 days after challenge. Examination revealed that her dental materials contained nickel, as deter mined by X-ray fluorescence spectroscope. In addition, the patient had been consuming boiled Japanese barnyard millet as part of her diet. She was advised to avoid this food and to commence a low-nickel diet (3) together with sodium chromoglycate.