Acute lymphoblastic leukaemia after bone marrow transplantation for aplastic anaemia.

An 11.5-year-old girl developed acute lymphoblastic leukaemia 7 months after bone marrow transplantation for severe aplastic anaemia. Before transplantation there were neither morphologic nor cytogenetic abnormalities to suggest preleukaemia. The conditioning regimen consisted only of cyclophosphamide. At the time of development of acute lymphoblastic leukaemia, chromosome analysis showed the blasts to be of host origin with clonal abnormalities including monosomy 7. Such a preleukaemic syndrome presenting as severe aplastic anaemia is a very rare event (the case reported here is the only one of 436 patients in Seattle) and cannot be reliably excluded before transplantation.