Tetraploid acute promyelocytic leukemia with double translocation t (15,17) PML/RARA: the first case report in Croatia and Europe

Abstract

Acute promyelocytic leukemia (APL) is characterized by the translocation t (15;17)(q22;q21) cytogenetic abnormality in the majority of cases. In most of the cases the cells of APL have normal, diploid karyotype. There are very few cases presented with very rare tetraploid karyotype with double translocation t(15;17)(q22;q12). We report the first case of tetraploid APL with double translocation t(15, 17) in Europe. A 66-year old male patient presented with dyspnea and unexplained dental bleeding. Blood work showed a white blood cell count of 1x109/L, hemoglobin was 124 g/L, platelet count was 61x109/L and fibrinogen level was low (1.4 g/L). Cytogenetics showed a tetraploid karyotype. Fluorescence in situ hybridization analysis proved existence of clonal cells with translocation t (15,17) in 15% of metaphase nuclei and tetraploid subclonal cells with the same translocation in 70% of metaphase nuclei. Findings were consistent with APL, tetraploid variant and the patient started all-trans retinoic acid (ATRA) treatment. The patient achieved complete remission in 2 months and completed three consolidation therapy cycles with ATRA, idarubicin or mitraxontrate. Currently, the patient is undergoing maintenance therapy with ATRA, 6-mercaptopurine and weekly methotrexate.