Cystic Lung Disease in Older Patients with Birt-Hogg-Dubé Syndrome

<bold>Background:</bold> Birt-Hogg-Dubé syndrome (BHD) is a rare autosomal dominant disease characterized by the development of lung cysts, skin fibrofolliculomas, and an increased risk for renal cancer. The progression of cystic lung disease with aging in BHD has not been well-characterized. <bold>Objectives:</bold> To assess the severity of lung involvement in patients with BHD aged 50 years or older. <bold>Material and Methods.</bold> A retrospective computer-assisted search was performed to identify patients with BHD seen at Mayo Clinic in Rochester, Minnesota and the First Affiliated Hospital of University of Science and Technology of China from January 2000 through May 2023. Demographic, clinical, pulmonary function, and radiologic parameters were extracted and analyzed. <bold>Results:</bold> Among 82 patients with BHD aged 50 years or older, 49 (59%) were female and the median age was 57 years (range, 50-79) at baseline. Pneumothorax had occurred in 46 patients (56%). Lung cysts were observed on CT in 77 patients (94%) and were bilateral in nearly all cases. The number of cysts was ≥10 for most patients (84%) and the median size of the largest cyst was 31 mm (range, 4-160 mm). Median (range) % predicted values of FVC, FEV1, and DLco was 98 (62-147), 92 (56-145), and 85 (61-133), respectively, for those with data available. During follow-up (median, 41 months; range, 3-259), 35%of patients manifested worsening in pulmonary function or cystic lung disease. <bold>Conclusion:</bold> Lung involvement in older patients with BHD manifests varying severity of cystic lung disease with relatively mild functional impairment, if any, and indolent progression.