Fig. 4

Non-proportional Venn diagram of lung, muscle and skin involvement in idiopathic inflammatory myopathies (IIM). The current view of IIM considers individuals with myositis, dermatitis, or both existing along a spectrum of illness, i.e. polymyositis (PM), dermatomyositis (DM), and clinically amyopathic dermatomyositis (CADM). Some of these individuals have circulating myositis-specific antibodies (MSAs), the presence of which can aid in the diagnosis. Incorporation of interstitial lung disease (ILD) into this disease paradigm would emphasize the true multisystem nature of this disease process and allow for more refined classification criteria