1. Department of Respiratory Diseases, Chinese People's Liberation Army General Hospital, Beijing 100853, P.R. China
2. Department of Thoracic Surgery, Chinese People's Liberation Army General Hospital, Beijing 100853, P.R. China
3. Department of Respiratory Diseases, Hainan Branch of Chinese People's Liberation Army General Hospital, Sanya, Hainan 572013, P.R. China
4. Department of Pathology, Hainan Branch of Chinese People's Liberation Army General Hospital, Sanya, Hainan 572013, P.R. China