What is Polymyositis? Polymyositis (PM) is an inflammatory myopathy characterized by proximal muscle weakness and evidence of muscle inflammation, including elevated muscle enzymes and electromyography confirming myopathy.

What causes Polymyositis?

The etiology of the inflammatory myopathy in Polymyositis has not been elucidated. However, it is thought to result from immune-mediated injury. Unlike other inflammatory myopathies, Polymyositis specific antibodies have not been found. Polymyositis also does not exhibit the systemic symptoms seen in other inflammatory myopathies. Because of the lack of disease- specific characteristics, the classification of Polymyositis has been called into question, but is currently considered a disease of exclusion.

Source: Baig, S., & Paik, J. J. (2020). Inflammatory muscle disease – An update. Best Practice & Research Clinical Rheumatology, 34(1), 101484. https://doi.org/10.1016/j.berh.2019.101484