[1] Yonsei Univ, Severance Hosp, Div Pulmonol, Coll Med,Dept Internal Med,Inst Chest Dis, 50-1 Yonsei Ro, Seoul 03722, South Korea
[2] Yonsei Univ, Severance Hosp, Dept Pathol, Coll Med, Seoul, South Korea
[3] Yonsei Univ, Severance Hosp, Dept Internal Med, Coll Med,Div Hematol, Seoul, South Korea