Morphological and immunological characteristics of BM cells in AML-M2/M3 patients. A, B: Bone marrow smears demonstrated hyperplasia of the myeloid lineage. Myeloblasts and abnormal promyelocytes accounted for >30% of BM cells. Abnormal promyelocytes were round, oval, or elliptical. The cytoplasm contained intense dust-like azurophilic granulation and some abnormal promyelocytes contained Auer rods. The nuclear size and shape were irregular; the nucleus could either appear kidney-shape, cerebriform, or even bi-lobed, with inconspicuous to prominent nucleoli. C: MPO: 99% positive; D: AS-DCE: 70% positive; E: NSE: particle positive; F: NSE positive cells were inhibited by NaF. G-L: Immunophenotype as determined by FCM for Case 7 showing two distinct groups of blast cells (red and green).