WHAT ARE PLEURAL EFFUSIONS AND PLEURAL DISEASE?
The outside covering of the lungs and inside covering of the chest wall are very thin, transparent membranes called pleural membranes. They provide a smooth surface so the lungs can slide up and down within the chest cavity during breathing. When the membranes become inflamed, thickened, or involved with a disease process (such as cancer) we speak of the patient as having pleural disease. Pleural fluid, also known as pleural effusion, may be one manifestation of pleural disease. Pleural effusion is an abnormal collection of fluid within the pleural space actually the “potential” space between the membrane lining the lung and the membrane lining the inside of the thoracic cavity. Normally, these two membranes touch each other as the lungs slide up and down during breathing. Pleural fluid may accumulate between these two membranes, spreading them apart and filling the potential space with fluid; this creates an abnormal shadow on the chest Xray, as shown in Figure 1. Pleural disease can
