Acute megakaryoblastic leukaemia with extreme thrombocytosis and p190 ^bcr/abl rearrangement

Acute megakaryoblastic leukaemia (AML-M7) is an uncommon disease, composing 0.5–1.2% of newly diagnosed adult acute myeloid leukaemias (AML). It is characterised by higher incidence and complexity of cytogenetic abnormalities. We report a rare case of Philadelphia (Ph) chromosome-positive AML-M7, presenting with extreme thrombocytosis and having a poor outcome. The diagnosis was established on the basis of morphological and flow cytometry data for megakaryoblastic proliferation in the bone marrow. Cytogenetics revealed 47,XX,+8,t(9;22)(q34;q11), and p190^BCR-ABL-rearrangement was detected. MDR1-gene overexpression was not demonstrated; however, the patient was resistant to therapy and died in 6 months. The reported case contributes to the overt heterogeneity of Ph-positive AMLs, which warrants further investigation and understanding.