TYPES:
There are two types of pleurisy: dry and wet pleurisy. In dry pleurisy, the more common condition, the inflamed pleurae rub directly against each other. In wet pleurisy, fluid oozes from the inflamed tissue into the space between the lungs and the chest wall. This fluid may compress the lungs, making breathing difficult.

Both types of pleurisy often occur as complications of respiratory tract infections, such as pneumonia, viral infections, and tuberculosis, and are more likely to develop in persons who are highly susceptible to such infections. They also can be caused by a tumor or an injury.

Some cases are due to certain gastrointestinal tract diseases, particularly of the liver and pancreas, which can inflame the diaphragm (the large muscle separating the chest and abdominal cavities) and the portions of the pleurae that cover the diaphragm.