This proliferation originates in the bone marrow, but involves the peripheral blood and other organs. Differentiate AML type by cell morphology, cytochemistry, phenotype, and genotype.
Myeloblasts have nuclei with fine, delicate chromatin and most often prominant nucleoli.
Note that myeloblasts do not magically mature from myeloblasts with no granules to fully granulated promyelocytes. Three stages in the cytoplasmic maturation of a myeloblast are recognized. Type I myeloblasts have no azuriphilic primary granules nor Auer rods. Auer rods may be seen. No azuriphilic primary granules.