1. Division of Hematopathology, Tohoku University Hospital, Sendai;
2. Department of Internal Medicine, Japanese Red Cross Ishinomaki Hospital, Ishinomaki;
3. Department of Hematology and Rheumatology, Tohoku University Graduate School of Medicine, Sendai; and
4. Department of Pathology, Japanese Red Cross Ishinomaki Hospital, Ishinomaki, Japan.