An unusual systemic inflammatory disease that mainly affects the muscles. Skin and muscle symptoms occur in dermatomyositis. PM and DM have the same clinical symptoms but different pathogenesis. DM has complement-dependent membranolysis of intramuscular capillaries, whereas PM is associated with cytotoxic T lymphocytes.
Indications: Suspicion of polymyositis (PM), dermatomyositis (DM) or overlap syndrome with myositis.
Many organs may be involved and the diagnosis is established by means of histological tests of muscle biopsy, EMG, leakage of muscle enzymes. Serological investigation: IMAGE