Background Organizing pneumonia (OP), different name: bronchiolitis obliterans with organizing pneumonia (BOOP), is a form of interstitial lung diseases characterized by presence of buds of granulation tissue in bronchiole and alveoli. Radiographic feature of OP is diffuse alveolar opacities which are similar to bacterial pneumonia and tumors. There are two types of OP; cryptogenic OP and secondary OP. Secondary OP is associated with many entities such as infection, drugs and connective tissue diseases including RA. However, clinical features of OP in patients with RA remain unclear
Objectives To clarify clinical features of OP associated with RA, particularly, to determine whether the development of OP is related to disease activity of arthritis.
Methods To determine prevalence of OP, we reviewed medical records of consecutive 499 RA patients who visited our hospital in Dec 2010. For analysis of clinical features of OP, we analyzed medical records of 24 RA patients with OP; 19 extracted by the above screening and additional 5 who admitted our hospital because of OP in 2011-12. OP was diagnosed by pathological findings or typical pulmonary imaging with clinical features (migration pulmonary infiltrates/ no response to antibiotics and good response to glucocorticoid).
Results Among 499 RA patients, patients with history of OP were 19 (3.8%) cases, while prevalence of interstitial pneumonia and with bronchoectasia/bronchiolitis were 13.0% and 6.0%, respectively. Among 24 patients, male was8 and female was 16. Age of the onset of OP was 60.5 ± 9.6 year (mean ± sd). RA preceded OP in 16 patients (67%), while OP developed simultaneously with RA in 3 patients, and occurred before the onset of RA in 3 cases. The interval between the onset of RA and OP was 11.6 ± 12.8 years. Positivity of RF and anti-CCP antibody were found in 18/24 and 14/17, respectively.
At the onset of OP, 18 patients were treated for RA, 11 and 7 of them received MTX and d TNF inhibotors, respectively. The disease activity of RA was high in 4, moderate in4, low in 9, and CR in 1 case. Only 3 patients showed exacerbation of arthritis.
Respiratory symptoms and fever were found in 14 and 18 out of 24 OP patients. All patients revealed alveolar opacities, multiple lung lesions were found in half of the cases, and spontaneous resolution of the lung infiltrates was found in 9 cases. antibiotics weres ineffective for OP and glucocorticoid dramatically improved OP. Relapse of OP was found in 5 patients without exacerbation of arthritis.
Conclusions OP is not a rare pulmonary complication in RA which develops in 4% in RA. OP develops in patients whose disease activity was controlled or in those treated with TNF inhibitors, successfully. These findings suggest that OP in RA might be TNF- independent and have different pathogenesis from arthritis.
Disclosure of Interest None Declared