Rheumatoid pleuritis

Overview
Rheumatoid pleuritis, a form of pleural effusion, is an uncommon complication of rheumatoid arthritis, occurring in 2-3% of patients (Walker and Wright, 1967; Naylor, 1990)

Histopathology
Light microscopy reveals replacement of normal cells lining the pleura (mesothelial cells) by a layer of pseudostratified epithelioid cells, multinucleated giant macrophages, and necrotic material (Mandl et al, 1969; Lillington et al 1971)

Clinical Characteristics
Pleural effusion usually occurs in patients previously diagnosed with rheumatoid arthritis, but it can also occur concurrently with or before the development of the joint manifestations of the disease (Graham, 1990; Chou and Chang, 2002). Patients may present with the signs of pleural effusion: dullness on percussion, diminished or absent breath sounds and vocal fremitus, and egophony at the level of the pleural liquid.

Diagnosis
Diagnosis relies on the characteristic cytology of the exudative pleural fluid, which contains elongated and giant multinucleated macrophages in a sea of amorphous granular material. The absence of mesothelial cells is also characteristic (Champion, 1968). While these findings are highly specific for rheumatoid pleuritis (Nosanchuk et al, 1968; Geisinger, 1985; Engel, 1986; Montes, 1988; Shinto, 1988), rheumatoid pleuritis must be considered if more than one of the above cytologic findings are detected.

Treatment
Steroids are the mainstay of treatment for rheumatoid arthritis, and have been shown to improve rheumatoid pleuritis.