A simultaneous onset of organizing pneumonia and rheumatoid arthritis, along with a review of the literature.

Organizing pneumonia (OP) is a specific type of interstitial pneumonia that has been noted as one of the pulmonary manifestations during the course of rheumatoid arthritis (RA). In this study, we report a case with a simultaneous development of OP and RA. The patient presented with concurrent flu-like symptoms and arthralgia of multiple joints, and antibiotic therapy was not effective. The rheumatoid factor (RF) and anti-cyclic citrullinated antibodies were both high. Multiple air-space opacities on chest radiographs and bilateral peripheral consolidations on high-resolution computed tomography films were evident. The histology of transbronchial lung biopsy samples was characterized by intra-alveolar buds of granulation tissue consisting of intermixed myofibroblasts and connective tissues. Treatment with prednisolone induced a complete recovery from OP without relapses. Our review of previous reports about RA-associated OP (RA-OP) suggested that the high titer of RF and increased disease activity of RA indicate a great risk of developing OP. This condition may represent a lung's reaction in the RA-associated inflammatory and/or immune process. We should be aware of RA-OP cases in which pulmonary manifestations precede articular symptoms. In these cases, respiratory manifestations are the main evidence of RA activity. In most cases of steroid-resistant RA-OP, the use of immunosuppressants was effective. Since OP may progress to fibrotic lung disease during the course of RA, we may consider performing a second lung biopsy for steroid-resistant patients, even if they have once been diagnosed as OP.