CD13およびCD33陰性急性骨髄球性白血病（FAB分類；M2）の形態学的変化と再発時のCD13発現

[CD13- and CD33-negative acute myelocytic leukemia (FAB classification; M2) with morphological changes and CD13 expression on recurrence].

• Y Aoyama
• T Yamane
• H Kanashima
• Y Takeoka
• K Koh
• Y Nakao
• R Yamamura
• H Nakamae
• K Ohta
• T Inoue
• M Hino
• N Tatsumi

抄録

42歳の男性が1998年7月に急性骨髄球性白血病と診断された．染色体異常はt(8;21)(q22;q22)であったが，表面抗原検査では骨髄性白血病に特徴的なCD13，CD33の発現は認められなかった．併用化学療法の結果、完全寛解し、妹からのドナー細胞を用いた同種骨髄移植が行われた。しかし、残念ながら白血病発症から約18ヶ月後に患者は死亡した。再発時の所見を初診時と比較すると、非分化未熟細胞（AML-M1）の形態学的変化とCD13表面抗原発現が認められた。発症時にはCD13もCD33も発現していないが、再発時にはCD13が発現している稀なAML症例と考えられた。

A 42-year-old man was diagnosed as having acute myelocytic leukemia in July 1998. The leukemic cells tended to be differentiated, and on the basis of positive peroxidase staining, this case was considered to be AML (M2) according to the FAB classification. t(8;21)(q22;q22) chromosomal abnormality was observed, but surface antigen analysis revealed no expression of either CD13 or CD33, a finding characteristic of myelocytic leukemia. Combination chemotherapy resulted in complete remission, and allogeneic bone marrow transplantation was performed with donor cells from the patient's sister. Unfortunately, however, the patient died about 18 months after the onset of leukemia. Comparison of the findings at recurrence with those at initial diagnosis revealed morphological changes in non-differentiated immature cells (AML-M1) and CD13 surface antigen expression. This was considered to be a rare case of AML with neither CD13 nor CD33 expression at onset, but with CD13 expression at recurrence.