<unk> , a form  of pleural effusion, is an uncommon complication of<unk>  arthritis, occurring in 2-3% of patients (Walker and Wright, 1967; Naylor, 1990)
Rheumatoid pleuritis
Cavitary pneumonia
Tuberculous pericarditis
Lung abscess
Hypertrophic pulmonary osteoarthropathy
Tuberculosis
Atypical pneumonia
Radiation induced pericarditis