Pericarditis is an inflammation of the sac that contains the heart. Radiation to treat cancer or from accidents with radioactive materials can damage the pleura and lead to exudates. A wide variety of autoimmune diseases attacks the pleura. Many other rare conditions can also lead to exudates. Major trauma can sever blood vessels in the chest, causing them to bleed into the pleural space.
Cancers can ooze blood as well as fluid.
They do not usually bleed massively. Chyle Occasionally, the liquid that comes out of the chest is neither transparent nor bloody, but milky. It is milky because it is transporting fats absorbed in the process of digestion. Injury from major trauma, such as an automobile accident. Cancers eroding into the thoracic duct.