What are idiopathic inflammatory myopathies?

Rare heterogenous muscle disorders, chronic and progerssive symmetrical proximal muscle weakness, can result in impaired indurance and disability, may be isolated muscle disorder, can be associated with other CT disorders [sjogren, SSc, SLE, RA]. Subclassified into polymyositis (PM), dermatomyositis (DM), and inclusion body myositis (IBM) with some other new subtypes (necrotizing, chronic granulomatous sarcoidosis, orbital, focal) We have serology of myositis specific and myositis associated antibodies (MSA and MAA).