Lymphoid Blast Crisis Is a Natural Course of Minor Breakpoint Cluster Region-Positive Chronic Myelogenous Leukemia

Mina Hur, Dong Soon Lee, Han Ik Cho, Seoksan Jung, Sunyang Park

Laboratory Hematology 7:65-68
©2001 Carden Jennings Publishing Co., Ltd.

Patients with Philadelphia (Ph) chromosome-positive chronic myelogenous leukemia (CML) and a breakpoint located in the minor breakpoint cluster region (m-BCR) have rarely been reported. We report a case of a 69-year-old woman presenting with CML in lymphoid blast crisis who had an m-BCR breakpoint and a bone marrow showing myeloproliferative features such as increased granulopoiesis and megakaryopoiesis with focal fibrosis and an increased number of blasts. The leukemia was in complete remission after induction chemotherapy, but m-BCR e1a2 fusion transcripts were persistently detected during the remission period. Six months later, the patient developed a second lymphoid blast crisis and an additional Ph chromosome was observed. Along with the 2 previously reported cases of m-BCR CML with an onset of lymphoid blast crisis, this case strongly suggests that an m-BCR fusion transcript induces lymphoid differentiation during the crisis.    

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