Pulmonary complications of polymyositis and dermatomyositis.

Polymyositis and dermatomyositis are systemic inflammatory diseases with unknown etiology and prognosis. Pulmonary involvement is increasingly recognized to be a major complication and a common cause of morbidity and mortality in these diseases. Thus a thorough pulmonary evaluation is necessary to permit appropriate management. There are three categories of pulmonary complications in myositis: aspiration pneumonia, hypoventilation, and interstitial lung disease (ILD). ILD is a frequent pulmonary complication in patients with myositis, and respiratory symptoms are not reliable signs for diagnosis. The strongest predictive factor for ILD in patients with myositis is the presence of antihistidyl transfer ribonucleic acid (tRNA) synthetase antibodies (anti-Jo-1), but ILD may also be present in patients without these autoantibodies. Therefore, all patients with polymyositis or dermatomyositis should be investigated with chest radiography, high-resolution computed tomography, and lung function tests.