MPAL

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MARKERS USEFUL TO CONFIRM PRIMITIVE NATURE OF BLAST CELLS
Useful markers of primitive nature The first step in AML diagnosis to establish the primitive nature of the abnormal cells: (1) Typically AML blasts have low CD45 expression and cause low side scatter. This means that they form a relatively uniform and distinctive population that is clearly separate from that of lymphocytes on CD45/SSc plots (for further details see this section). It is important to realise however also not all AML cases may fit this pattern low CD45/low SSc pattern - particularly APL and monocytic AML. (2) Additional markers often expressed on myeloid cells may help confirm the primitive nature of the cells: in AML this is most often CD34, although other markers may contribute and are also listed.
CD45	A marker expressed by all leukocytes and their precursors. In AML expression is characteristically "weak" i.e. significantly less intense than normal lymphocytes or monocytes. In monocytic AML expression may be stronger.
CD34	Frequently expressed by AML blast cells (40-80% of cases) - most often in less differentiated forms of AML. Expression is also seein frequently (and often more strongly) in ALL
Other markers that may be associated with primitive nature in AML
In the context of a proven AML diagnosis a number of markers may be expressed that are considered to predominantly reflect their primitive nature. Some of these are more frequently associated with lymphoid disorders, but providing other criteria for AML are met their presence does not change lineage assignment. These include TDT, CD7, other?

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