[1] Hakodate Municipal Hosp, Dept Hematol, 1-10-1 Minato Cho, Hakodate, Hokkaido 0418680, Japan
[2] Hakodate Municipal Hosp, Dept Gastroenterol, Hakodate, Hokkaido 0418680, Japan
[3] Hokkaido Univ, Grad Sch Med, Dept Hematol, Sapporo, Hokkaido 0600808, Japan