PMC7481999_01
Bone marrow at diagnosis of promyelocytic blast crisis. Promyelocytes with multiple Auer rods (a) and sliding plate nuclear morphology (b) in bone marrow aspirate smears. The bone marrow clot section demonstrates a mildly hypercellular bone marrow with increased promyelocytes (c).
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The bone marrow revealed a mildly hypercellular marrow largely replaced by promyelocytes (67% by manual aspirate differential count; Figure 1).
Cytogenetic findings at the time of promyelocytic blast crisis. (a) Conventional karyotype demonstrating t(15;17) (black arrows) and t(9;22) (red arrows) translocations. (b) FISH probes positive for the PML-RARA fusion. (c) FISH probes positive for the BCR-ABL1 fusion (dual-color, dual-fusion probes).
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Routine cytogenetic analysis demonstrated an abnormal cell line containing t(9;22)(q34;q11.2) with a simultaneous t(15;17)(q22;q21) translocation involving 18 of 20 metaphases examined (Figure 2); the two remaining cells showed a normal male karyotype.
BCR-ABL1 and PML-RARA fusion products over time. CML, chronic myeloid leukemia; F/C, fusion to control ratio.
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Analysis of multiple samples demonstrated that the PML-RARA bcr3 fusion product was first detectable 8 months prior to the onset of promyelocytic blast crisis (Table 2; Figure 3).