1. Department of Respiratory Medicine, National Hospital Organization, Ibaraki Higashi National Hospital, Tokai‑mura, Ibaraki 319‑1113, Japan
2. Department of Pathology, Tokyo Women's Medical University Yachiyo Medical Center, Yachio, Chiba 276‑8524, Japan
3. Department of Respiratory Surgery, National Hospital Organization, Ibaraki Higashi National Hospital, Tokai‑mura, Ibaraki 319‑1113, Japan
4. Department of Pulmonary Medicine, Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki 305‑8576, Japan
5. Department of Pathology, National Hospital Organization, Ibaraki Higashi National Hospital, Tokai‑mura, Ibaraki 319‑1113, Japan