Abstract
Spontaneous pneumothorax (SP), as the first manifestation of lung cancer, is relatively rare, with reported occurrence rate of between 0.03% and 0.05%. The mechanism of concurrent pneumothorax with lung cancer is not clear, however several theories were proposed, including tumor necrosis mechanism and rupture of the bulla which contains tumor. We herein report two cases of lung cancer, in which the initial manifestations was only limited to SP. Without any radiologic abnormalities preoperatively, wedge resection of bullatous lung and subsequent histologic study followed. Pathologic study revealed the presence of bullatous change of the lung and combined lung cancer.