Types of muscle abnormalities seen in Systemic Sclerosis
1. Mild proximal weakness due to a noninflammatory benign myopathy. On histology, this myopathy looks normal or shows a type 2 muscle fiber atrophy. This pattern of fiber loss is seen with inactivity and corticosteroid use. The muscle enzymes are typically normal.
2. Mild elevation of muscles enzymes with waxing and waning of symptoms. Muscle biopsy reveals interstitial fibrosis and fiber atrophy. Minimal inflammatory cell infiltration is noted. Should not be treated with corticosteroids.
3. Inflammatory type of myopathy with elevated muscle enzymes (as seen with polymyositis). These patients are considered to have an overlap syndrome, and many fit the definition of mixed connective tissue disease. Should be treated with immunosuppressive therapy.
