Myeloid blast phase of chronic myelogenous leukemia, BCR-ABL1+, associated with a secondary translocation involving MLL: case report and review of the literature

Although secondary cytogenetic aberrations are frequent in myeloid blast phase (MBP) of chronic myelogenous leukemia, BCR-ABL1+ (CML), balanced translocations of the type that are recurrent in de novo acute myeloid leukemia (AML) are unusual in the setting of CML-MBP, and rearrangement of MLL as a secondary event in CML-MBP is extremely rare. We present a case of CML-MBP in which a translocation involving MLL was acquired as a secondary abnormality and review the relevant literature. The clinical, morphologic, immunophenotypic, and genetic findings were reviewed. A search of the relevant literature was performed. We report a case of CML presenting in MBP, in which a balanced translocation involving MLL was identified as a secondary cytogenetic aberration. The specific translocation seen in this case, t(3;11)(q21;q23), which is rare in de novo AML, has not to our knowledge been reported in the context of CML-MBP. Upon the completion of induction therapy, and attainment of morphologic remission of the acute leukemia, the secondary MLL translocation became undetectable, though BCR-ABL1 persisted. Although published examples are extremely rare, CML-MBP may be associated with secondary translocations involving MLL.