Myositis-Related Interstitial Lung Diseases: Diagnostic Features, Treatment, and Complications.

Abstract

Idiopathic inflammatory myopathies (IIMs) are a group of rare, heterogeneous connective tissue diseases marked by skeletal muscle inflammation. The four main forms of IIMs include dermatomyositis (DM), polymyositis (PM), inclusion body myositis (IBM), and immune-mediated necrotizing myopathy (IMNM). Anti-synthetase syndrome (ASyS) is a very important classification of the IIM phenotypical spectrum and can be associated with rapidly progressive pulmonary disease. Each form of myositis, except inclusion body myositis, can be associated with multisystem organ involvement including pulmonary, cardiac, arthritis, and skin. The lung in DM, PM and ASyS is the most common extra-muscular organ in IIM with a spectrum ranging from mild to fatal interstitial lung disease (ILD) with or without muscle involvement. Given that there is a subset of myositis patients with rapidly progressive ILD, it is important that rheumatologists in particular assess for lung involvement in all patients with myositis. In recent years, serologic testing for myositis autoantibodies has been more readily available allowing clinicians to order these tests commercially. The evaluation of a patient with myositis not only includes clinical phenotyping but also close observation to tendency for and rapidity of lung progression as well as serologic phenotyping with autoantibodies which can guide the treatment plan and prognosis of patients with ILD. Herein, essential aspects of recognition, diagnosis, monitoring of progression, scope of treatment and IIM-ILD related complications are discussed.