Myeloid to lymphoid clonal succession following autologous transplantation in second chronic phase of chronic myeloid leukaemia.

ABSTRACT

A 23-year-old male found to have Philadelphia chromosome-positive chronic myeloid leukemia (CML) in May 1987 suffered a myeloid blastic transformation in April 1993. A second chronic phase was achieved after treatment with daunorubicin and cytosine arabinoside and the patient then underwent autologous bone marrow transplantation (ABMT) using previously cryopreserved chronic phase bone marrow. Examination of his marrow during the second chronic phase revealed a double Philadelphia chromosome in 15% of metaphases examined and in rearrangement of the immunoglobulin heavy chain gene joining region using Southern blot analysis. Following transplantation, his marrow regenerated into lymphoid blast crisis with three distinct immunoglobulin gene rearrangements visible, one of which corresponded in size to the detected rearrangement pre-transplant. This case is consistent with myeloid to lymphoid clonal succession underlying recurrent blast crises in a patient with CML and suggests the co-existence of both clones prior to ABMT.