1. Respiratory Disease Center Yokohama City University Medical Center 4‐57 Urafune‐cho, Minami‐ku Yokohama 232‐0024 Japan
2. Division of Pathology Yokohama City University Medical Center 4‐57 Urafune‐cho, Minami‐ku Yokohama 232‐0024 Japan
3. Department of Pulmonology Yokohama City University Graduate School of Medicine 3‐9 Fukuura, Kanazawa‐ku Yokohama 236‐0004 Japan