Pleuritis as a presenting manifestation of rheumatoid arthritis: diagnostic clues in pleural fluid cytology.

Pleural effusion is a recognized but relatively uncommon complication of rheumatoid arthritis and has distinctive cytopathologic features. It may occur before, concurrently with, or after the development of joint manifestations of the disease. Clinical diagnosis of rheumatoid pleuritis may be delayed or overlooked in a patient without obvious evidence of arthritis. Failure to recognize the unique cytologic picture of rheumatoid pleuritis caused a 5-month delay in diagnosis of a rheumatoid pleural effusion in an elderly man whose concurrent arthritic symptoms were not given adequate clinical recognition.