1. Blood Disorders Center, Aiiku Hospital, Sapporo, Hokkaido 064‑0804, Japan
2. Department of Gastroenterology, Aiiku Hospital, Sapporo, Hokkaido 064‑0804, Japan
3. Department of Cancer Pathology, Faculty of Medicine, Hokkaido University, Sapporo, Hokkaido 060‑8638, Japan