Recurrence of acute lymphoblastic leukemia in donor cells after allogeneic marrow transplantation associated with a deletion of the long arm of chromosome 6.

This report concerns a woman who experienced a relapse of acute lymphoblastic leukemia (ALL) associated with an interstitial deletion of the long arm of chromosome 6 in donor cells more than 4 years after allogeneic bone marrow transplantation (BMT). Direct bone marrow preparations revealed the presence of two leukemic clones 46,XY,del(6)(q23q25) and 45,X,-4,del(6)(q23q25),+8,-15,-21,+i(21q), +mar, the former clearly indicating that male donor cells were involved in the malignant process. Relapse as evidenced by these chromosome anomalies was confined to metaphases from directly prepared marrow cells and phytohemagglutinin (PHA)-stimulated peripheral blood cells. Cytogenetic analyses of T cell colonies gave predominantly normal donor karyotypes (65 of 69 mitoses) along with three host mitoses and a single donor metaphase carrying the 6q- anomaly. The marrow stroma, as represented by first-passage adherent layer cells from long-term marrow cultures, showed 17 of 19 host metaphases. One of two donor cells found within the stromal elements exhibited a 6q- chromosome. In the subsequent remission mitoses derived from myeloid and lymphoid cells were exclusively of donor origin, and chromosomal abnormalities could no longer be detected. Stromal elements remained host-derived (14 of 16 mitoses).