Jonghoo Lee1, Chi Hoon Maeng2, Jae-Uk Song3. 1. Department of Internal Medicine, Jeju National University Hospital, Jeju National University School of Medicine, Jeju, South Korea. Electronic address: lovlet@paran.com. 2. Division of Medical Oncology-Hematology, Department of Internal Medicine, Kyung Hee University Hospital College of Medicine, Kyung Hee University, Seoul, South Korea. 3. Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, South Korea.