[A case of rheumatoid arthritis with a remarkable left-right difference in pulmonary lesions and acute exacerbation of pneumonia].

A 59-year-old woman had a four-year history of rheumatoid arthritis. Despite treatment with prednisolone for interstitial pneumonia, her chest X-ray films revealed gradual progression of reticular shadows, mainly in the left lung, and during the third hospitalization she died of respiratory failure due to acute exacerbation of pneumonia. At autopsy, there was a remarkable difference in lung weight: left 250 g, right 510 g. Microscopically, the pulmonary lesion was mild fibrosing interstitial pneumonia, with remarkable luminal organization and macrophages in parts. The features of unilateral interstitial pneumonia with bronchiolitis obliterans organizing pneumonia were clearer in the left lung. The cause of the acute exacerbation and of the difference in interstitial pneumonia between sides could not be identified.