[Rheumatoid pleurisy. Apropos of 13 cases].

The extra-articular manifestations of RA are numerous and various. Among the latter, pleural involvement is not exceptional, but it is often overlooked for it may be latent. There have been few recent studies of this relationship. The authors report 13 cases of rheumatoid pleurisy collected over the last 7 years in rheumatology and chest units. They recall the frequency of pleurisy, their constitutional background, their clinical and radiological appearances and emphasise the diagnostic interest of a biochemical study of the pleural fluid: a fall in the glucose content and of complement levels are the main changes. A study of the complement system carried out in 11 patients showed a fall in total complement and of the C3 and C4 fractions in the pleural fluid, which shows local consumption of immunological origin. This factor and the clinical picture may be important in diagnosis. The course of these pleural effusions is favourable, complications are exceptional; their treatment is mainly the basic treatment of RA.