Answer is C (CD15 / 34 both seen in same cell) Acute promyelocytic Leukaemia (PML : FAB M3) * This is a type of Acute Myeloid Leukaemia (AML) and has been classified as the M3 category according to the FAB morphological classification.9 * It constitutes 5 - 10% of all AML (Robbin's / Ghai) Pathological characteristic of PML * It is characterized by the chromosomal translocation 1(15;17)Q - CMDT * t(1 5;17) translocation produces a fusion gene ( PML-RAR }involving the Retinoic Acid Receptor gene and Promyelocytic Leukemia (PML) gene. This PML - RaR fusion protein tends to suppress gene transcription and blocks differentiation of cells. This block can be overcome with pharmacological doses of retinoic acid (Harrrison). * Most cells are hypergranularQ promyelocytes often with many Auer rods per cell. Presentation characteristic / Specific features of PML * Patients of PML are younger (median age 35 - 40 years) - Robbin's * Incidence of Disseminated Intravascular Coagulation (DIVC) is high in patient with PML. -Robbin's DIC may occur with any subgroup of AML but is especially common in acute PML (M3)-Ghai Treatment specific to PML subject All-Trans Retinoic Acid (ATRA/Tretinoin) * The treatment of patient with PML has been dramatically improved by the use of All - Trans - Retinoic acid. This agent is an analog of vitamin A that leads to terminal differentiation of occult promyelocytic leukemia cells. - CMDT * Remission in PML is induced by All - Trans-Retinoic acid as a single agent -Ghai Arsenic Trioxide Arsenic Trioxide produces meaningful response in upto 85% of patients refractory to tretinoin