Polymyositis presents with proximal muscle weakness due to cell mediated damage of muscle fibres. A differentiation from other inflammatory muscle disorders is essential. Treatment aims at controlling the immune response. Polymyositis is an inflammatory muscle disease of unknown origin. It commonly affects women with peak incidence between 50 – 70 years with a subacute or chronic onset.
It is rarely seen in individuals less than 18 years. Along with dermatomyositis and inclusion body myositis, it has been categorised under the group of idiopathic inflammatory myositis. Pathophysiology Though the exact etiology is unknown, current evidence strongly suggests an autoimmune origin. An underlying defect in cell-mediated immunity triggers CD8+ T lymphocytes to infiltrate and damage the muscle fibres. The triggering factors are speculated to be: Autoimmune antibodies against muscle antigens …
