Abstract
To evaluate pulmonary involvement in polymyositis, 26 patients were studied roentgenologically, functionally and histologically. Chest X-ray findings on admission revealed diffuse interstitial patterns in 11 patients (42.3%), of which 6 showed signs of lung shrinkage. With steroid therapy, muscular weakness improved in 20 patients (76.9%). In contrast, the interstitial patterns on chest X-ray films appeared or progressed in 21 patients (80.8%) during the course of therapy. No cases of improved chest X-ray findings were observed. The interstitial patterns showed micronodular and linear shadows in many cases, and reticulonodular and ring-like shadows in a few cases. Pleural and pericardial effusions were found in 4 and 5 patients, respectively. These chest X-ray findings were frequently seen from 1 to 10 years after onset of polymyositis. Pulmonary fibrosis preceded polymyositis in 1 case, and pleural effusion preceded in an other case. Respiratory functions tested after improvement of muscular weakness showed a restrictive pattern, low diffusion capacity and hypoxemia in many cases with interstitial patterns on chest X-ray film. Histological findings by transbronchial lung biopsy in 2 patients revealed interstitial fibrosis without inflammatory cell infiltration.
These results suggest that interstitial lung disease occurs in polymyositis more frequently than previously reported, and that the lung disease progresses slowly even with steroid therapy.
