Myositis-Associated Interstitial Lung Disease

Interstitial lung disease (ILD) is the most common form of lung involvement in myositis and results in significant morbidity and mortality. ILD can appear in a patient with known or suspected myositis with classic muscle and skin features of myositis or can be the first or dominant presentation in many cases. ILD can present as chronic progressive mild dyspnea on exertion or cough but may also present as acute fulminant respiratory failure. The diagnosis of ILD is made in patients with consistent history and physical findings who have restrictive lung function and reduced diffusing capacity on PFTs and characteristic imaging findings on high-resolution chest CT scan. While the overall prognosis of myositis-associated ILD is good, patients with rapidly progressive ILD are at increased risk for death and should be treated aggressively. Additional poor prognostic markers include the presence of antisynthetase antibodies other than Jo-1, MDA5 antibody, elevated CRP and ESR, advanced age, and elevated ferritin. The mainstay of therapy is immunosuppression, and the approach to treatment is governed by the severity of the lung disease. In select patients with progressive ILD despite therapy, lung transplantation may be an option of last resort.