Macrophagic myofasciitis unrelated to vaccination.

Macrophagic myofasciitis (MMF) is known to be closely associated to vaccination containing aluminium as an adjuvant. Here we describe a case of MMF unrelated to vaccination, and presented as focal tender muscle in a 59-year-old woman. Magnetic resonance imaging showed evidence of unilateral myofasciitis involving muscles and fascias of the vastus lateralis. Open biopsy showed a unique pathological pattern of MMF. Our case suggests that other causes unrelated to vaccination need to be investigated in the pathogenesis of MMF, and MMF could be considered in the differential diagnosis of patients with focal muscle tenderness.