Sonographic features of vaccination granulomas in children with delayed-type hypersensitivity to aluminum

In this article, we report the sonographic features of vaccination granulomas in three children sensitized to aluminum. Although the recognition of the vaccination granuloma relies on the clinical examination, misdiagnosis is frequent, leading to distressful procedures or prolonged antibiotic administration. In all our cases, sonography revealed a teardrop-shaped echogenic central structure, suggesting the deposition of aluminum crystals along the route of administration with consequent subcutaneous degenerative changes, and a surrounding hypoechoic cap, which reflects the changeable inflammatory reaction and the granuloma formation.