Lung Cysts, Spontaneous Pneumothorax, and Genetic Associations in 89 Families with Birt-Hogg-Dubé Syndrome

Rationale: Birt-Hogg-Dubesyndrome (BHDS) is an autosomal, dominantly inherited genodermatosis that predisposes to fibro- folliculomas, kidney neoplasms, lung cysts, and spontaneous pneumothorax. Objectives: We evaluated 198 patients from 89 families with BHDS to characterize the risk factors for pneumothorax and genotype- pulmonary associations. Methods: Helical computed tomography scans of the chest were used to screen for pulmonary abnormalities. BHD mutation data were used for genotype-pulmonary associations. We examined the relationship of pneumothorax with categorical parameters (sex, smoking history, and lung cysts) and continuous parameters (num- ber of cysts, lung cyst volume, and largest cyst diameter and vol- ume). Logistic regression analyses were used to identify the risk factors associated with pneumothorax. Measurements and Main Results: Twenty-four percent (48/198) of patients with BHDS had a history of pneumothorax. The presence of lung cysts was significantly associated with pneumothorax (p 0.006). Total lung cyst volume, largest cyst diameter and volume, and every parameter related to the number of lung cysts were significantly associated (p 0.0001) with pneumothorax. A logistic regression analysis showed that only the total number of cysts in the right parenchymal lower lobe and the total number of cysts located on the pleural surface in the right middle lobe were needed to classify a patient as to whether or not he or she was likely to have a pneumothorax. Exon location of the BHD mutation was associated with the numbers of cysts (p 0.0002). Conclusions: This study indicates that patients with BHDS have a significant association between lung cysts and spontaneous pneumothorax.