Pleural involvement in rheumatoid arthritis (RA) by thoracic ultrasound: a pilot study.

<bold>Background:</bold> Prevalence, clinical impact and extent of pleural involvement in RA patients (RA-P) are still controversial. <bold>Aim:</bold> To assess the presence and characteristics of pleural involvement in RA-P. <bold>Methods:</bold> RA outpatients without known pleuro-parenchymal involvement and control subjects with no pleuro-pulmonary pathologies were evaluated using thoracic ultrasound (TUS). A 14-zone TUS protocol was performed. Along with TUS findings, rheumatological and respiratory data were collected. <bold>Results:</bold> 22 RA-P and 8 controls were included. The two groups did not differ in gender, BMI, professional exposure, smoking habits, FEV1 and FVC; RA-P were older than controls (p=0.03). Pleural abnormalities were detected in 11 RA-P and in one control (50% vs 12%; p=0.09). In RA-P the most common findings were pleural thickenings (84%) and subpleural nodules (16%), while pleural effusion was never detected. Concerning the sites of pleural involvement, the anterior zones were less affected compared to both lateral and posterior zones (4%, 44% and 48% respectively; p<0.001). Inferior zones were significantly more involved than superior zones (76% vs. 24%; p=0.01). Two patients (18%) had diffuse involvement (more than 4 zones affected). Age, BMI, gender, smoking habits, professional hazards, respiratory function and signs of articular inflammation were similar in RA-P with or without pleural abnormalities <bold>Conclusions:</bold> Pleural involvement, as assessed by TUS, was detected in half RA-P. It is mainly characterized by pleural thickenings and subpleural nodules mostly located in the lateral and postero-inferior zones of the chest. TUS may improve clinical information during RA-P evaluation.