Rare systemic processes that affect muscles with proimal muscle weakness, muscle enzyme elevations, fever, weakness, weight loss and rash.
Classified by: presentation, age of onset, skin and muscle biopsy pathologic findings.
Includes: dermatomyositis, polymyositis, juvenile dermatomyositis, immune mediated necrotizing myopathy, and sporadic inclusion body myositis.
A fifth disease, overlap myositis is increasingly recognized.
Inflammatory muscle diseases largest group of treatable myopathies in children and adults.
Heterogeneous disorders classified on basis of of clinicopathologic features.
Each subtype has a different prognosis and treatment response.
Associated with increased difficulty using proximal muscles as with climbing stairs, lifting, and getting out of a chair.