Pleural effusions of extravascular origin.

Most pleural effusions are caused by hydrostatic and oncotic pressure imbalance, inflammation or infection, or abnormalities in lymphatic drainage. A select number of effusions are caused by fluid of extravascular origin. Some of these effusions result from complications of treatment, whereas others are a ramification of the underlying disease. The incidence, pathogenesis, clinical presentation, chest radiographic manifestations, pleural fluid analysis, diagnosis, and management are discussed.