1. The First Department of Internal Medicine, School of Medicine, University of Occupational and Environmental Health, Kitakyushu, Japan
2. Working Group on the Rheumatoid Arthritis-associated Lymphoproliferative Disorders of the Japan College of Rheumatology, Tokyo, Japan
3. Tobata General Hospital, Kitakyushu, Japan
4. Division of Rheumatology, Department of Internal Medicine, Keio University School of Medicine, Tokyo, Japan
5. Department of Advanced Medicine for Rheumatic Diseases, Graduate School of Medicine, Kyoto University, Kyoto, Japan
6. Department of Rheumatology and Clinical Immunology, Wakayama Medical University, Wakayama, Japan
7. Department of Rheumatology, Tokyo Women’s Medical University School of Medicine, Tokyo, Japan
8. Division of Rheumatology, Tokai University Hachioji Hospital, Tokyo, Japan