The term spontaneous pneumothorax means the presence of air in the pleural cavity and is descriptive of the type of pneumothorax which occurs in apparently normal persons. This condition is also called idiopathic pneumothorax, but this implies pneumothorax without any known cause, while a cause can be attributed in many cases of spontaneous pneumothorax. It excludes cases due to artificial means, such as direct trauma, and to ulcerative communication between the alimentary tract and the pleural spaces.
This condition is very rare and is usually associated with fluid exudate of some sort, such as serum (hydropneumothorax), pus (pyopneumothorax) or even blood (hemopneumothorax).
There are three types of spontaneous pneumothorax: the open, in which the rent in the surface of the lung remains patulous; the closed, in which the rent is healed or held in position by the positive pressure of the air in the pleural cavity,