Spontaneous pneumothorax is divided into primary and secondary. Primary SP most commonly afflicts the young and healthy. The secondary type can develop with obstruction, infection, infarction, neoplasm and diffuse lung disease.
SP as a complication of primary lung carcinoma (LC) is rare [6, 7]. It is estimated that only 2% of all SP is coexistent with malignant lung diseases, either primary or secondary. This tumor complication must be especially considered in older patients .
To date, among the 1200 adults who were found to have SP from 1970–2007, 37 (3%) had lung cancer. In all such patients, the pneumothorax occurred in the same side as the carcinoma. The main cause of SP was the rupture of a necrotic tumor nodule or necrosis of subpleural metastases (for 21 patients). It also became the communication cause between the bronchus and pleural cavity, producing a bronchopleural fistula that resulted in pneumothorax. We demonstrate that these case reports of lung cancer with pneumothorax are a rare complication of primary lung carcinoma.
The mechanism producing pneumothorax from lung cancer is not well understood, but a number of theories have been advanced. The first is that it may be the result of tumor necrosis – rupture of the necrotic neoplastic tissue in the pleural cavity ; the second, that it may be caused by the rupture of the necrotic tumor nodule or necrosis of subpleural metastases . A third is cancer of the check valve mechanism: the tumor at the lung periphery can obstruct bronchioles and lead to local overdistention and rupture of the lung . The fourth is that most patients with lung cancer have chronic bronchitis or emphysema bullae and these bullae may rupture following the disturbance of the lung architecture due to bronchial cancer .
Pneumothorax related to therapy has been reported in patients receiving chemotherapy and/or radiotherapy for lung cancer . There is the possibility that SP and lung cancer are two independent and incidental processes. These theories suggest that lung cancer should always be considered as a possible cause of SP in older patients .