Two Cases of Acute Leukemic Transformation with a Chromosome 17 Abnormality and p53 Overexpression Evolving from Essential Thrombocythemia

Essential thrombocythemia (ET) is a clonalmyeloproliferative disorder that can rarely transform into acute leukemia in 1∼5% of cases. A recent study has found that a significant proportion of leukemic cases from ET were associated with a cytogenetic abnormality (17p deletion). Herein, we report two cases of acute myeloid leukemic transformations harboring a 17p abnormality from a series of 119 ET patients. The first case, a 48-year-old female, developed acute myeloid leukemia with maturation (AML-M2) ac- companying myelodysplasia was diagnosed 6.1 years after the initial diagnosis of ET. She was treated with hydroxyurea. Her karyotype showed a monosomy 17. The second case, a 61-year-old male, developed acute megakaryoblastic leukemia (AML-M7) with a very complex hyperdiploidy including addition of 17p13 that developed 6.5 years after the initial diagnosis. He was treated with hydroxyurea and anagrelide. The immunohistochemistry showed p53 overexpression in both cases. Our cases support the specificity of chromosome 17 abnormality and p53 overexpression in acute leukemic transformation from ET.