Injection-site granuloma due to aluminum

Area of Science:

• Immunology
• Dermatopathology
• Vaccinology

Background:

• Subcutaneous nodules can occur at vaccine injection sites.
• Tetanus toxoid vaccines often contain aluminum adjuvants.

Purpose of the Study:

• To investigate the histopathological findings of subcutaneous nodules observed after tetanus toxoid vaccine administration.
• To determine the potential cause of these nodules.

Main Methods:

• Biopsy of subcutaneous nodules from three patients.
• Microscopic examination of tissue samples.
• Solochrome-azurin staining for aluminum crystals.

Main Results:

• Histopathology revealed granulomatous inflammation with lymphoid follicles, immune cell infiltrates (lymphocytes, histiocytes, plasma cells, eosinophils), and occasional eosinophilic necrosis.
• Dense fibrous bands were noted in some samples.
• Aluminum crystals were identified in nodules from two of the three patients.

Conclusions:

• The observed subcutaneous nodules are likely a complication of inoculations with aluminum-containing vaccines.
• Granulomatous inflammation is a key histopathological feature.