Morphologic features and in vitro ATRA sensitivity of the patient with clonal der(2)t(2;17)(q32;q21). (A) Day 1 (left panel): peripheral blood smear shows abnormal promyelocytes with bi-lobed or sharply indented nucleus and microgranulated cytoplasm. Some promyelocytes have Auer rods (Wright-Giemsa, ×1000). Core biopsy shows hypercellular bone marrow infiltrated by leukemic cells with high nucleocytoplasmic ratios and indented or irregular nuclear contours (H&E, ×400). Day 14 (middle panel): bone marrow touch preparation shows persistence of blasts and abnormal promyelocytes in addition to a few myelocytes or metamyelocytes (Wright-Giemsa, ×1000). Conversely, core biopsy reveals more differentiated granulocytes (H&E, ×400). Day 28 (right panel): bone marrow examination shows normocellular marrow with complete differentiation. (B) Leukemic cells of the patient show neutrophilic differentiation with 1μM ATRA treatment. ATRA induces differentiation of NB4 and HL60 cells. (Wright-Giemsa, ×1000). The image was acquired using a BX51 microscope (Olympus), ×1000 and ×400 lenses, and a DP25 digital camera (Olympus).