Macrophagic myofasciitis (MMF) is an inflammatory myopathy, recently described ([1][2]). Clinical symptoms include myalgias, arthralgias, muscle weakness, asthenia, and fever. Diagnosis is based on deltoid muscle biopsy that usually shows specific histologic abnormalities
S. Guis et al Arthritis Care & Research Volume 47, Issue 5 , Pages 543 - 545

A new inflammatory myopathy, called macrophagic myofasciitis, is being seen in increasing numbers. The disease usually affects adults, with no sex predominance. Macrophagic myofasciitis generally becomes manifest as muscle pain (myalgias) of variable intensity, observed in 95% of the patients, usually associated with chronic debilitating fatigue (90%). Myalgias predominantly affect the limbs – notably the legs – and are often aggravated by exertion. Joint pain, primarily affecting the large peripheral articulations is noted in 50–60% of the patients and a moderate febrile syndrome in 30%.

Histology images

The emergence of a new type of histopathological lesion of unknown origin called macrophagic myofasciitis (MMF), characterized by a unique myopathological pattern, has been reported.
MMF is characterized by centripetal infiltration of the epimysium, perimysium and perifascicular endomysium by non-periodic-acid-shiff (PAS) positive cells of macrophage lineage with osmiophilic crystal inclusions. MMF has been mainly detected by deltoid muscle biopsy in adult patients, although it has also been detected by quadriceps muscle biopsy in 3 young children. The histopathological lesion is localized at these sites.

Macrophagic myofasciitis is characterised by sheets of macrophages in striated muscle, a few lymphocytes and inconspicuous muscle fibre damage. It is due to aluminium contained in vaccines, and is localised to the inoculation site. We report the first Australian case, detected incidentally when investigating a raised serum creatine kinase level.