1 Background Idiopathic inflammatory myopathies (IIMs) encompass a group of highly diverse systemic autoimmune disorders characterized by chronic muscle weakness, inflammation and extramuscular symptoms [1]. These disorders are further categorized into several subtypes: dermatomyositis (DM), juvenile dermatomyositis (JDM), anti-synthetase syndrome (ASS), immune-mediated necrotizing myopathy (IMNM), polymyositis (PM), inclusion body myositis (IBM) and overlap myositis.