Ultrastructure of systemic sclerosis inflammatory myopathy.

Muscle biopsies from 7 patients with systemic sclerosis (SS) and a slowly progressive proximal muscular weakness were studied ultrastructurally. In all cases an inflammatory myopathy was found exhibiting fibre atrophy, occasional fibre necrosis, connective tissue proliferation, filamentous bodies, concentric laminated bodies and a mononuclear cell infiltration formed by lymphocytes, macrophages and mast cells. Capillary abnormalities included alterations of endothelium, thickening and reduplication of basement membrane and the presence of cylindric confronting cisternae. The different associations between muscle diseases and SS are grouped. Our data suggest that SS inflammatory myopathy is a distinct clinical and pathological entity.