ABSTRACT
Acute myeloid leukemia (AML) with minimal differentiation is an acute leukemia with no cytomorphologic or cytochemical evidence of myeloid differentiation. The immunophenotype of AML with minimal differentiation is similar to that of AML without maturation, and it is difficult to differentiate these two entities based on Flow cytometric (FC) analysis of blasts alone. Phenotyping by FC reveals blasts with low side scatter and moderate cluster of differentiation 45 and admixture of maturing myeloid precursors and neutrophils. The bone marrow (BM) is hypercellular and contains a mixed population of monocytes and their precursors, and granulocytes and their precursors. The monoblasts are slightly larger than myeloblasts and have an abundant cytoplasm, round nuclei with delicate lacy chromatin, and one or more large prominent nucleoli. Leukemic monocytes have an abundant cytoplasm that may show irregular borders with pseudopods and cytoplasmic vacuoles. Promonocytes tend to have irregular folded nuclei and pale, slightly basophilic cytoplasm with occasional azurophilic granules.
