Pleuritis-pericarditis--an unusual initial manifestation of mixed connective tissue disease.

Cardiac involvement has been reported in mixed connective tissue disease (MCTD). We describe a 16-year-old girl in whom pleuritis and pericarditis occurred as the initial clinical manifestations of MCTD. Although pleuritis and pericarditis form a common clinical entity in MCTD, it is rarely seen as an initial manifestation. If MCTD is suspected, the diagnosis can be made by the clinical findings and the occurrence of a high titre of antibody against ribonuclease-sensitive ribonucleoprotein (RNP). This report emphasizes the importance of screening for connective tissue disease in patients with pericarditis/pleuritis.