Pulmonary capillaritis and diffuse alveolar hemorrhage. A primary manifestation of polymyositis.

Polymyositis is often complicated by either usual interstitial pneumonitis, diffuse alveolar damage, cellular interstitial pneumonitis, or bronchiolitis obliterans-organizing pneumonia. Pulmonary capillaritis, a distinct interstitial reaction associated with diffuse alveolar hemorrhage, occurs with the systemic vasculitides and some collagen vascular diseases. It has not been described in patients with polymyositis. We describe two patients who developed a relatively acute onset of polymyositis based on the appearance of a severe proximal myopathy, elevated serum creatine phosphokinase levels, compatible electromyographic abnormalities, inflammatory muscle biopsies, and in one case, the presence of serum anti-Jo-1 antibodies. Concomitant with their muscle disease, they developed respiratory failure that proved to be pulmonary capillaritis with varying degrees of diffuse alveolar hemorrhage as well as bronchiolitis obliterans-organizing pneumonia. Although those reactions are reported to occur with other collagen vascular diseases, these two cases are the first reports of pulmonary capillaritis and diffuse alveolar hemorrhage complicating polymyositis.