Pulmonary fibrosis is common, and although pulmonary function abnormalities hae been reported in as many as 40% of patients with RA, the chest radiograph is normal in more than half of these patients.

• RA常发生肺纤维化。据报道RA出现肺功能障碍机率约40%25，但即使如此胸片仍可过半数无发现。