Background: The development of persistent itchy nodules at the injection site following hyposensitization therapy with aluminium-precipitated antigen extract has been described in several reports. Occasionally, contact allergy to aluminium has been reported in individuals with such nodules.
Objectives: To investigate if hyposensitization therapy can induce contact allergy to aluminium and examine if there is any association between persistent subcutaneous nodules and aluminium allergy.
Patients/methods: Sixty-one children with allergic asthma and/or allergic rhinitis participated in the study of whom 37 had had hyposensitization therapy. The study consisted of a non-clinical part based on a questionnaire and a clinical part with a physical examination, self-assessment of itching, and patch testing. To secure an unbiased evaluation of possible reactions, the investigators were blinded.
Results: Contact allergy to aluminium was found in eight participants, all in the exposed group (8/37 versus 0/24, P = 0.02). Examination showed nodules on the upper arms in 13 participants, all in the group exposed to hyposensitization therapy. Nodules were over-represented in patients with contact allergy to aluminium.
Conclusions: There was a statistically significant association between contact allergy to aluminium and persistent subcutaneous nodules in children who had had hyposensitization therapy.