Abstract
We present a rare case of cystic bronchioloalveolar cacinoma (BAC) which was complicated by spontaneous pneumothorax. Descriptions about the mechanism of cysts and complications of pneumothorax in BAC are few in the literature. Check-valve mechanism is one of these factors which may be responsible for the cystic lesions and spontaneous pneumothorax in cystic BAC. Narrowing of the respiratory bronchioles by the tumor cells should be a cause of the check-valve mechanism. In our case, high resolution CT (HRCT) showed that some of the cysts have a connection with the airways, which was confirmed by pathology. This case is original because the connection between the airways and cysts was supported by not only pathology specimens but also HRCT. (Turk Toraks Derg 2012; 13: 178-80)