Bone marrow smears of cases of APL. A - classical morphology: the leukemic cells present a folded nucleus and a broad and hypergranular cytoplasm. Several cells present Auer rods (upper left and lower middle). B – variant morphology: the neoplastic cells present an oval or bilobated nucleus and few small granula in the less abundant cytoplasm. May-Grünwald-Giemsa. x1000..