MACROPHAGIC MYOFASCIITIS - AN EMERGING ENTITY

Background An unusual inflammatory myopathy characterised by an infilt ration of non-epithelioid histiocytic cells has been recorded with inc reasing frequency in the past 5 years in France. We reassessed some of these cases. Methods We did a retrospective analysis of 18 such cases seen in five myopathology centres between May, 1993, and December, 19 97. The myopathological changes were reassessed at a clinopathology se minar. Findings Detailed clinical information was available for 14 pat ients. The main presumptive diagnoses were polymyositis and polymyalgi a rheumatica. Symptoms included myalgias in 12 patients, arthralgias i n nine, muscle weakness in six, pronounced asthenia in five, and fever in four. Abnormal laboratory findings were occasionally observed, and included raised creatine kinase concentrations, increased erythrocyte sedimentation rate, and myopathic electromyography. Muscle biopsy sho wed infiltration of the subcutaneous tissue, epimysium, perimysium, an d perifascicular endomysium by sheets of large macrophages, with a fin ely granular PAS-positive content. Also present were occasional CD8 T cells, and inconspicuous muscle-fibre damage. Epithelioid and giant ce lls, necrosis, and mitotic figures were not seen. The images were easi ly distinguishable from sarcoid myopathy and fasciitis-panniculitis sy ndromes. Whipple's disease, Mycobacterium avium intracellulare infecti on, and malakoplakia could not be confirmed. Ten patients were treated with various combinations of steroids and antibiotics; symptoms impro ved in eight patients, and stabilised in two. Interpretation A new inf lammatory muscle disorder of unknown cause, characterised by a distinc tive pathological pattern of macrophagic myofasciitis, is emerging in France.