We report a childhood case that showed the repeated appearance and disappea
rance of various kinds of cytogenetic abnormalities (CA) for 5.5 years afte
r allogeneic bone marrow transplantation (BMT). The patient underwent allog
eneic BMT from an HLA-matched unrelated donor during the second complete re
mission of acute lymphoblastic leukemia. The conditioning regimen for BMT c
onsisted of etoposide, cyclophosphamide. anti-human thymocyte immunoglobuli
n, and total body irradiation. There were no leukemic relapses or secondary
acute myeloid leukemia/myelodysplastic syndrome (AML/MDS) since the BMT. T
he CA occurred from residual recipient cells, which were damaged by chemoth
erapy or radiation prior to BMT. Although previous studies about post-BMT C
A had reported the continuous emergence of identical clones, the present ca
se showed the appearance of one different type of clone after another. Alth
ough the appearance of different types of CA may mean that these clones did
not obtain any growth advantages, it may be a sign of genomic instability,
which is probably a risk factor for the development of secondary AML/MDS.
(C) 2001 The Japanese Society of Hematology.