Abstract
Lung involvement is the leading cause of mortality in inflammatory myopathy. A careful
assessment of clinical and serologic manifestations especially myositis-associated
autoantibodies allows precise classification of the different phenotypes of inflammatory
myopathy and stratification of the risk of lung involvement. About three out of four
patients with inflammatory myopathy develop interstitial lung disease (ILD), which
represents the main cause of morbidity and mortality. In patients with a confirmed
diagnosis of inflammatory myopathy, the approach to the diagnosis of ILD includes
assessment of clinical and functional severity, evaluation of the high-resolution
computed tomography pattern of disease, which often suggests nonspecific interstitial
pneumonia or organizing pneumonia. Bronchoalveolar lavage to rule out infection is
often performed; however, video-assisted thoracoscopic lung biopsy is now generally
discouraged, unless malignancy is suspected. The so-called antisynthetase syndrome
characterized by the combination of mechanics' hands, Raynaud' phenomenon, myositis
often mild or absent, and presence of one of the anti-tRNA synthetase antibodies is
associated with a 70% risk of ILD, especially in subjects with antibodies other than
anti-Jo1 antibodies (i.e., anti-PL7 or -PL12 antibodies). Treatment depends on both
severity and progression of ILD, often including a combination of corticosteroids
and immunosuppressive therapy. Rituximab-based regimen has showed promising results
in retrospective studies for the management of refractory or rapidly progressive forms
of ILD. Clinical trials are ongoing to evaluate the actual efficacy of this strategy
on mortality related to lung disease. Secondary pulmonary complications of inflammatory
myopathy include opportunistic infections, aspiration pneumonia, pneumomediastinum,
ventilatory failure due to diaphragmatic muscular weakness, drug-induced pneumonitis,
and rarely pulmonary hypertension.
Keywords inflammatory myopathy - dermatomyositis - polymyositis - antisynthetase syndrome -
interstitial lung disease - anti-PL7 or -PL12 antibodies
