(Cotran, p 751.) Pneumothorax refers to the accumulation of air in the pleural cavity. Types of pneumothorax include spontaneous pneumothorax, traumatic pneumothorax, and therapeutic pneumothorax. Spontaneous pneumothorax is most commonly associated with emphysema, asthma, and tuberculosis. One special type, however, is idiopathic spontaneous pneumothorax, which occurs primarily in young people. This disorder results from rupture of subpleural blebs. These blebs are most often located in the apex of the lung, and rupture is usually related to stretching or raising the arms. Recurrence of idiopathic spontaneous pneumothorax is common.