[Atelectasis of the right lower lobe in association with bronchiolitis obliterans organizing pneumonia].

A 58-year-old woman with underlying rheumatoid arthritis was admitted to the hospital because of a dry cough and the presence of an abnormal shadow in the right lower lung field. Consolidation and volume loss in the right lower lobe with air bronchogram were recognized on a chest tomogram. Bronchofiberscopic examination disclosed neither stenosis nor tumors in the large bronchi. Organizing pneumonia was recognized pathologically in transbronchial lung biopsy (TBLB) specimens. The volume of the right lower lobe decreased rapidly, and new infiltration shadows appeared in the right upper and middle lobes. Another bronchofiberscope examination revealed organizing pneumonia, and macrophage infiltrations were seen in the alveoli on histopathological examination of the TBLB specimens. The diagnosis of RA-associated BOOP was made on the basis of agreement of the expansion of the shadows on chest radiographs, the RA symptoms and the RA factor. The patient was treated with prednisolone, and the clinical course was satisfactory, with no recurrence. This case was of interest because BOOP inducing lobar cicatricial atelectasis is very rare.