Pulmonary fibrosis in rheumatoid arthritis: a review of clinical features and therapy.

During the past four decades there has been a growing appreciation of the frequency of pulmonary abnormalities associated with RA. Approximately 30% to 40% of patients with RA demonstrate either radiographic or pulmonary function abnormalities indicative of interstitial fibrosis or restrictive lung disease. The severity of pulmonary fibrosis is not associated with rheumatologic symptoms or the duration of the associated RA, nor is there any clear relation to the extraarticular features of RA or serologic findings. Survival rates in patients with coexisting RA and pulmonary fibrosis are similar to those of patients with idiopathic pulmonary fibrosis. However, the spectrum of disease activity is quite variable. The majority of patients with progressive pulmonary symptomatology, when treated with corticosteroids, will have equivocal results. Some patients appear to respond to immunosuppressive or cytotoxic medications. The role of macrophages may be central to the injury to lung. Recent studies suggest a potential treatment role for cyclosporine, which may be able to interrupt lymphocyte-stimulated macrophage activation, and thus, fibroblast-mediated fibrosis in patients with pulmonary interstitial fibrosis. Bronchoalveolar lavage studies may delineate subgroups of patients who are more likely to respond to immunosuppressive agents, especially when treatment is started early.