Macrophagic myofasciitis: a challenging diagnosis

Area of Science:

• Neurology
• Immunology
• Pathology

Background:

• Macrophagic myofasciitis (MMF) is a rare inflammatory myopathy.
• It is characterized by the presence of abundant macrophages in muscle tissue, often associated with aluminum deposits.
• The condition is suspected to be linked to vaccinations containing aluminum adjuvants.

Observation:

• A 25-year-old male presented with a 3-year history of insidious onset generalized muscle pain.
• Symptoms included exercise intolerance and decreased muscle strength, necessitating gait support.
• Initial investigations including analytical tests, imaging, and electromyography showed no abnormalities.

Findings:

• Muscle biopsy revealed a predominantly macrophagic inflammatory infiltrate.
• Significant aluminum deposits were identified within the muscle tissue.
• These findings were suggestive of macrophagic myofasciitis (MMF).

Implications:

• This case suggests a potential association between MMF and prior vaccinations, even years after administration.
• MMF diagnosis requires a minimum interval of 18 months post-aluminum exposure for pathological confirmation.
• The findings underscore the importance of considering MMF in patients with unexplained chronic myopathy and a history of vaccination.