Acute leukaemia types: Difference between revisions
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<span style="color: black; font-size:90%;></br>The first step in AML diagnosis to establish the primitive nature of the abnormal cells:</br> | <span style="color: black; font-size:90%;></br>The first step in AML diagnosis to establish the primitive nature of the abnormal cells:</br> | ||
<span style="color: | <span style="color: black; font-size:90%;>'''(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 ([[CD45|for further details see this section]]) also not all AML forms may fit this pattern - particularly [[APL]] and [[monocytic AML]].</br> | ||
<span style="color: float:left; black; font-size:90%;>'''(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.</br> | <span style="color: float:left; black; font-size:90%;>'''(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.</br> |
Revision as of 23:30, 21 July 2023
AML DIGANOSIS: MARKERS OF PRIMITIVE NATURE
(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) also not all AML forms may fit this 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. | |
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Useful markers of primitive cells | |
CD45 | Expressed leukocytes and their precursors; in AML expression is "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. Although expression is also frequent (and often stronger) in ALL |
Markers that may be helpful in some cases | |
TDT | Expressed in some cases of AML (5-20%) particularly in less differentiated blast cells, often on a sub-population of cells. More typically associated with ALL. |
CD7 | Predominantly seen as a T-cell antigen, CD7 tends may be expressed by AML blasts (20-40%) where it most often indicates a more primitive forms or MPAL. CD7 is most consistently a marker of T-lineage (including T-ALL).
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AML DIGANOSIS: MARKERS CONFIRMING MYELOID ORIGIN OF BLAST 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, allowing their identification. However, it is important also to be aware of other cells that may occupy that area (for further details see this section) and that some forms of AML forms may not fit this pattern - particularly APL and monocytic AML; while So morphology is essential to confirm a primitive appearance and nature (2) It is often also possible to detect markers associated with primitive nature: in AML this is most often CD34, but other markers may contribute.
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Frequently expressed markers of myeloid lineage | |
MPO | A strong lineage marker for AML (expressed in around 80% of cases) that when detected by flow cytometry is diagnostic of myeloid differentiation (AML or MPAL) although potentially gives less confident evidence on immunocytochemistry. |
CD117 | An early marker of myeloid lineage seen in around 80% of AML often recognising more primitive forms, aberrant expression in up to 20% of ALL |
CD33 | A good marker for AML that is often less strongly expressed in monocytic forms |
CD13 | A good lineage marker for AML aquired a little later, higher than CD13 in monocytic forms |
Markers helpful in confirming AML or suggesting subtypes | |
CD10 | One of tne of the first lineage-markers acquired in AML with good relative specificity |
CD11b | One of tne of the first lineage-markers acquired in AML with good relative specificity |
CD11c | One of tne of the first lineage-markers acquired in AML with good relative specificity |
CD14 | A good marker for AML that is often less strongly expressed in monocytic forms |
CD64 | A good lineage marker for AML aquired a little later, higher than CD13 in monocytic forms |