Do bullae and emphysema increase risk of pneumothorax in silicosis?

Background: The occurrence of occupational lung diseases is decreasing due to improvements in occupational health in recent years; however, silicosis and its complications remain important occupational health problems. We have studied the role of emphysema and bullae as predictive factors of secondary spontaneous pneumothorax in acute and accelerated silicosis.
Materials and Methods : This study was carried out using questionnaire items on occupational history and conventional computed tomography of lungs. Differences between two groups (silicosis with and without secondary spontaneous pneumothorax) in terms of age, interval of exposure-diagnosis and therefore silica exposure duration were assessed by independent t -test. Fisher′s exact test was used to determine the association between secondary spontaneous pneumothorax and both emphysema and bullae.
Results: We found a significant association between secondary spontaneous pneumothorax and bullae in acute and accelerated silicosis.
Conclusion: Pneumothorax in silicosis could be attributed to previous bullae.