ABSTRACT
Acute promyelocytic leukemia (APL) is a type of acute myeloid leukemia (AML) characterized by the presence of t(15;17)(q22;q21) translocation leading to fusion between PML and RARa gene. Treatment combining all-trans retinoic acid (ATRA) and arsenic trioxide (ATO) has dramatically improved the prognosis of APL. We report a rare finding of primary clone of t(15;17) followed by a sequential clonal evolution of additional derivative chromosome 6 formation by a two hit mechanism. Our case showed a good clinical response with a four years and nine months event free survival after ATRA and ATO combination therapy in spite of existence of three chromosomal abnormalities stating that targeted therapy overcomes the adverse effects of additional genetic markers. However, close monitoring with assessment for long term prognostic behavior is required.