PML and acute promyelocytic leukemia: Acute Promyelocytic Leukemia (APL) is a subtype of Acute Myeloid Leukemia (AML) characterized by a specific morphology of the tumor cells [1] and by a balanced reciprocal translocation t(15;17) which fuses the PML gene on chromosome 15 to the RARA gene on chromosome 17 [2-6].