Persistent subcutaneous nodules after immunotherapy injections for allergic asthma

Area of Science:

• Immunology
• Dermatology
• Allergology

Background:

• Allergen immunotherapy (AIT) involves repeated administration of allergens to induce tolerance.
• Adverse effects of AIT commonly include local reactions, but persistent nodules are rare.
• Aluminium hydroxide is a frequent adjuvant in vaccines and hyposensitization solutions, potentially causing local reactions.

Observation:

• A patient undergoing AIT for allergic asthma developed persistent, itchy subcutaneous nodules at injection sites.
• These nodules were a localized reaction to the allergen immunotherapy treatment.

Findings:

• The case highlights persistent subcutaneous nodules as a potential, albeit uncommon, adverse effect of allergen immunotherapy.
• The presence of aluminium hydroxide in the immunotherapy solution is suspected as the causative agent for these persistent local reactions.

Implications:

• Clinicians should be aware of the possibility of persistent nodule formation following AIT, particularly when using adjuvants like aluminium hydroxide.
• Further investigation into the mechanisms behind aluminium hydroxide-induced persistent local reactions in AIT may be warranted.
• This finding could inform the development of safer adjuvant formulations or alternative immunotherapy strategies.