Myeloid/natural killer cell precursor blast crisis of chronic myelogenous leukemia with two Philadelphia (Ph-1) chromosomes

We report on a 30-year-old patient with blast crisis of a chronic myelogeno us leukemia (CML) that shows immunophenotypic features similar to those of the myeloid/natural killer (NIK) cell precursor leukemia previously describ ed. Expression of CD13/CD33/CD65 as well as MPO +/LF- blasts was classified as a myelogenous blast crisis of a CML. In addition, the blasts were posit ive for. CD7/CD56. Other lymphoid markers were not expressed. Cytogenetic a nd molecular cytogenetic examinations showed two Philadelphia (Ph-1) chromo somes and a trisomy 8. Similar to expression of the myeloid/NK cell precurs or phenotype in acute myelogenous leukemia (AML), it is possible to exhibit this phenotype in Ph-1-positive CML. Only one case report of myeloid/NK pr ecursor phenotype blast crisis of CML was found in the literature. Therefor e, it is not clear whether this phenotype is a distinct biologic and clinic al disease entity of CML, as is the case in the respective AML phenotype.