| Table: Less frequent patterns of primitive phenotype;
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| In AML with monocytic maturation primitive cells that have significant monocytic maturation may have high side scatter (consistent with their size and cytological features) but some or all of the blast cells may also have high expression of CD45 comparable with normal monocytes, such cases may be difficult to distinguish from typical or transforming CMML. It is important to compare with clinical and morphological features to ensure appropriate classification.
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| AML with monocytic differentiation
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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, particular in mare mature monocytic forms where expression may resemble normal monocytes.
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| Acute promyelocytic leukaemia
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Frequently expressed by AML blast cells (40-80% of cases) - most often in less differentiated forms of AML. Expression is also seen frequently (and often more strongly) in ALL
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| Other patterns
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Frequently expressed by AML blast cells (70-80% of cases) - where it can support myeloid differentiation, CD117 also has some value in establishing primitive differentiation as it is lost as cells mature
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