Masked inv dup(22)(q11.23), tetrasomy 8 and trisomy 19 in a blast crisis-chronic myeloid leukemia after interrupted Imatinib-treatment

Background The Philadelphia (Ph) chromosome, or derivative chromosome 22 [der(22)], is a product of the reciprocal translocation t(9;22). It is the hallmark of chronic myelogenous leukemia (CML). It results in juxtaposition of the 5’ part of the BCR gene on chromosome 22 to the 3’ part of the ABL1 gene on chromosome 9. During CML progression 60–80 % of the cases acquire additional genetic changes. Blast crisis (BC) is characterized by the rapid expansion of a population of differentiation arrested blast cells (myeloid or lymphoid cells population), often presenting with secondary chromosomal abnormalities. Here we report an unusual CML-BC case with acquired secondary chromosomal aberrations observed after the patient had to interrupt a successful Imatinib treatment for overall 16 months.