Benign pleural diseases.

The pleural space is a potential space under normal physiologic circumstances. It envelops the lung, the mediastinum, the diaphragm and the chest wall. A thin film of pleural fluid provides lubrication for the two pleural layers; only 2-10 ml of pleural fluid is present in healthy people. For the purposes of this review, pleural abnormalities will be divided into pleural effusion, pneumothorax, and pleural calcification.