Muscle disease in progressive systemic sclerosis: diagnostic and therapeutic considerations.

Upon careful examination, 23 of 24 patients with progressive systemic sclerosis (PSS) were found to have abnormalities of muscle. Nineteen patients presented a homogenous pattern of muscle abnormalities, which untreated was associated with a stable course ("simple myopathy"). Three patients demonstrated inflammatory muscle disease indistinguishable from polymyositis while a fourth patient developed marked weakness associated with a generalized neuropathic process. Muscle enzymes, electromyogram, and muscle biopsy permitted distinction among the different muscle disorders, a distinction that could have prognostic and therapeutic importance.