Diffuse cystic lung diseases Jay H. Ryu 1 ;Xinlun Tian 2 ;Misbah Baqir 1 ;Kaifeng Xu 2 ; 1. Division of Pulmonary and Critical Care Medicine, Mayo Clinic, Rochester, MN 55905, USA ; 2. Division of Respiratory Medicine, Peking Union Medical College Hospital, Beijing 100730, China ; Fig.4 High-resolution CT scan of a 60-year-old man, ex-smoker, with Birt-Hogg-Dubé syndrome. Cystic lesions of varying sizes are present in both lungs with asymmetric distribution with otherwise normal-appearing lung parenchyma. This patient presented with abdominal discomfort related to a renal mass that proved to be a renal cell carcinoma and was incidentally noted to have cystic lung disease. Frontiers of Medicine,2013,7(3),316-327. Doi:10.1007/s11684-013-0269-z