Rheumatic diseases are frequently associated with interstitial lung disease. Since interstitial fibrosis is an irreversible process, understanding the mechanisms leading to fibrosis is necessary for the development of treatment strategies to prevent irreversible pulmonary damage. High-resolution Computed Tomography (HRCT) is superior to chest radiography in assessing the presence and extent of parenchymal abnormalities in diffuse infiltrative lung diseases and provides a sensitive and noninvasive method of quantifying global disease extent.
The aims of this study were to quantify the severity and extent of subclinical interstitial lung disease as depicted on HRCT and to study the relationship between the patterns of lung disease quantified by HRCT and the functional parameters and bronchoalveolar lavage findings in patients with rheumatic diseases.
Eighty nonsmoking patients (24 patients with systemic sclerosis, 24 with primary Sjögren's syndrome, 20 with rheumatoid arthritis and 7 with dermatopolymyositis) were examined. No patient had any signs or symptoms of pulmonary disease.
Thirty-three of 80 patients (41.2%) had abnormal HRCT findings, namely isolated septal/subpleural lines, irregular pleural margins and ground-glass appearance. Chest X-ray showed parenchymal abnormalities in only 15 patients (18.7%) who had evidence of fibrosis on HRCT. Abnormal differential cell counts (alveolitis) at bronchoalveolar lavage were found in 46 of 80 patients (57.5%). Three types of alveolitis were observed: pure lymphocyte alveolitis, pure neutrophil alveolitis, and neutrophil alveolitis associated with lymphocytosis (mixed alveolitis). The patients with neutrophil alveolitis had more extensive disease on HRCT than those with lymphocyte alveolitis or with normal cellular patterns at bronchoalveolar lavage. The extent of a reticular pattern on HRCT correlated with the neutrophil rate (p = 0.001) and total count (p = 0.003) on bronchoalveolar lavage. Eosinophil and lymphocyte rate and total count correlated (p < 0.05) with the extent of the ground-glass pattern on HRCT. Lung volumes were not significantly different among patients with ground-glass pattern and those with reticular patterns on HRCT, while the diffusing capacity for carbon monoxide was significantly lower (p < 0.05) in the latter.
HRCT is a sensitive tool in detecting interstitial lung disease in patients with rheumatic diseases with no signs and symptoms of pulmonary involvement. The relationship between the different HRCT patterns and bronchoalveolar lavage cell profiles can identify patients at higher risk of developing irreversible lung fibrosis. A long-term, prospective follow-up study is needed to determine whether these patients will develop over pulmonary disease.