Polymyositis and diffuse interstitial lung disease. A review of the pulmonary histopathologic findings.

A retrospective analysis was performed of 105 patients with polymyositis for eight years. Roentgenographic evidence of pulmonary interstitial disease was present in ten adult patients (9%) with polymyositis unassociated with other connective-tissue disorders. Review of the pulmonary histopathologic findings indicated a spectrum of pulmonary diffuse interstitial infiltrates and fibroplasia of the alveolar septae. Response to glucocorticoids with regard to pulmonary symptoms was variable in the patients studied. Therapeutic response seemed to be influenced by both the cellularity of the chronic interstitial infiltrates and the degree of fibroplasia of the alveolar septae. Electron microscopic studies of the lung tissue from two patients with polymyositis and diffuse interstitial lung disease failed to demonstrate either immune complexes or viral particles.