This is a subtype of AML, classified as AML-M3 FAB. It is also known as acute promyelocytic leukemia. It arises from a translocation between genetic regions on chromosomes 15 and 17. This translocation causes an arrest in white blood cell maturation in the bone marrow, leading to the accumulation and overproliferation of promyelocytes, a group of cells in the developmental pathway. Its treatment differs from other AML types.