Macrophagic myofasciitis: an atypical presentation for a rare disease with a challenging approach

Macrophagic myofasciitis (MMF) is a rare immune-mediated myopathy that seems to be triggered by aluminium hydroxide adjuvant used in vaccines. Its presentation is relatively heterogeneous and treatment with steroids leads to improvement, although there is little evidence regarding the role of other immunosuppressants. The histological findings in MMF seem to be the result of an abnormal presence in the inoculation site of aluminium, which can induce an immune-mediated muscular disease in susceptible persons. The authors describe the case of a patient with an atypical presentation of macrophagic myofasciitis, with histological confirmation in a muscle biopsy distant from the inoculation site, and a good therapeutic response to tacrolimus and mycophenolate mofetil, as well as a discussion on the pathologic basis, controversies and emerging treatments for this condition.