What is the WHO designation for FAB AML M3 under the French-American-British classification?

The correct designation for FAB AML M3 under the French-American-British classification is AML with t(15;17). This subtype of acute myeloid leukemia is associated with a specific genetic abnormality involving the translocation between chromosome 15 and chromosome 17. This translocation results in the formation of the promyelocytic leukemia-retinoic acid receptor alpha (PML-RARA) fusion gene, which plays a crucial role in the pathogenesis of this leukemia.

The identification of this translocation is significant because it not only affirms the diagnosis but also has implications for treatment. Patients with this subtype of acute myeloid leukemia often respond well to all-trans retinoic acid (ATRA) therapy, which can lead to remission in a large number of cases. The connection between the t(15;17) translocation and the biological behavior of M3 is a key point in understanding the disease and its management.

Other subtypes, which may involve different genetic abnormalities such as those found in mixed lineage or other translocations, do not specifically refer to the FAB AML M3 designation characterized by the t(15;17).