IX.B: Acute Myelogenous Leukemia

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IX.B.001

Acute myelogenous leukemia with minimal maturation. Flow cytometry. Staining pattern of marrow cells. The upper left panel shows the pattern of leukocyte common antigen (CD45) versus side-scatter. The leukemic blast population has dimmer CD45 staining than lymphocytes (the very bright population in the upper left of the graph), but with low side-scatter (right angle light scatter). This population accounts for 95% of all events. The remaining panels demonstrate some of the characteristic markers in myeloblasts (CD34 marks immature precursor cells; HLA-DR is a class II major histocompatibility antigen that is usually lost by the promyelocyte stage of maturation; CD13, CD33, and CD117 are markers characteristic of immature myeloid lineage).

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IX.B.002

Acute myelogenous leukemia with maturation. Flow cytometry. Staining pattern of marrow cells from a patient with acute myelogenous leukemia with maturation. The upper left panel shows the pattern on leukocyte common antigen (CD45) versus side-scatter. The leukemic blast population has dimmer CD45 staining than lymphocytes (the very bright population in the upper left of the graph), but with low side-scatter (right-angle light scatter). The marrow consists of a CD34+ blast population (shown in red) and more mature granulocytic elements (shown in green). The upper middle pattern shows forward angle and side-scatter light scatter for all cells in the sample. The upper far right plot and the lower left plot show the blast phenotype (CD34+, CD117+, CD33+), with gating only for blasts (shown in red). The lower right plot shows the pattern of CD34 and CD33 for all cells (with blasts highlighted in red and the other maturing myeloid elements shown in green). Although not shown, the blast population in this case was HLA-DR+, in contrast to the leukemic cell population seen in acute promyelocytic leukemia.

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IX.B.003

Acute promyelocytic leukemia. Flow cytometry. Staining pattern of marrow cells from a patient with acute promyelocytic leukemia. The upper left panel shows the pattern on leukocyte common antigen (CD45) versus side-scatter. The leukemic promyelocyte population has more side-scatter (right-angle light scatter) than myeloblasts (see patterns for AML-M1 and AML-M2 for reference). The upper middle pattern shows forward angle and side-scatter light scatter for all cells in the sample with the leukemic population highlighted in red. The remaining plots show the typical marker profile (CD13+, CD33+, CD34-, HLA-DR-, and bright CD9+). Lack of HLA-DR staining is seen in about 95% of cases and helps to differentiate acute promyelocytic leukemia from other acute myeloid leukemias, which are typically HLA-DR+ in the blast population.