A New Complex Variant 4-Point Break Three-Way Translocation Involving Chromosomes 8, 15 and 17 in a Patient with Acute Promyelocytic Leukemia: A Case Report and Literature Review

Abstract

The genetic hallmark of Acute promyelocytic leukemia (APL) is the balanced reciprocal translocation t(15;17)(q24;q21), resulting in the PML::RARα fusion gene. Although the majority of APL patients carry the typical t(15;17), variant translocations involving three or more chromosomes have also been described. We report a case of a 59-year-old man showing clinical, morphologic, laboratory, and immunophenotypic findings of APL. Cytogenetic analysis revealed a variant complex 4-point break-three-way translocation involving chromosomes 8p, 15q and 17q. Dual-color dual-fusion fluorescence in situ hybridization (D-FISH) analysis showed a typical pattern with two PML::RARα fusion signals, one on the derivative chromosome 17 and one on the derivative chromosome 8. Real-time quantitative reverse transcription polymerase chain reaction (RT-PCR) for PML::RARα transcripts was negative. These results illustrate the usefulness of combining cytogenetic and molecular analysis to identify the PML::RARα fusion gene in all cases with strong suspicion of APL.