Vaccination granuloma with confirmed aluminum allergy: two cases and a literature review.

Abstract

Background. Childhood vaccination remains a cornerstone of infection prevention. Aluminum (Al) salts are widely used as adjuvants to enhance vaccine immunogenicity, yet they can occasionally trigger adverse local reactions.
Objective. To highlight clinically and immunologically confirmed cases of aluminum-induced vaccination granulomas and their potential implications for vaccination adherence.
Methods. We report two pediatric cases presenting with pruritic subcutaneous nodules following immunization with Al-containing vaccines at the University Hospital Leuven, Belgium. Both patients underwent patch testing confirming Al sensitization, and ultrasonography demonstrated typical granulomatous lesions at the injection sites.
Results. The combination of confirmed Al hypersensitivity and ultrasound-verified granulomas underscores a clear causal relationship between Al exposure and granuloma formation. These findings stress the importance of recognizing this underdiagnosed condition to avoid unnecessary diagnostic procedures and to guide safe continuation of vaccination schedules.
Conclusion. Aluminum-induced vaccination granulomas, though uncommon, may contribute to incomplete immunization in sensitized children. Early recognition and appropriate management are essential to ensure full protection against preventable infectious diseases.