MPAL: Difference between revisions
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!colspan="2" <span style="font-size:90%; font-color:navy; style="text-align: left; border: 1px solid black; background:pale gray">|'''Requirements to assign myeloid lineage in MPAL'''</br></span> | |||
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<span style="font-size:80%; text-align:left;"></br>The assignment of myeloid lineage recognises MPO expression to be a defining marker of myeloid lineage. However MPO is expressed only by around 80% of AML cases. The assignment of myeloid lineage can therefore also be made if monocytic lineage can be established, requiring at least 2 of 5 possible lineage markers to be detected (although only 3 of these can be established by flow cytometry).</br> | |||
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Revision as of 10:23, 10 November 2023
Assignment of category to ambiguous cases in acute leukaemia:
Final lineage requires integration of additional molecular features; assignments made by flow are therefore "provisional" pending full molecular assessment. Four categories may be assigned:
- My/B
- My/T**
- T/B
- Undiff
MPAL with t(9;22) (q34.1;q11.2); BCR-ABL1) MPAL with t(v;11q23.3); with KMT2A re-arrangement
Flow cytometry is only one element in assigning a diagnosis of MPAL but conclusions may subsequently be modified by results of immunohistochemistry, cytogenetics, or genetics. It is important therefore that an element of uncertainty is acknowledged in assigning a diagnosis of MPAL by flow cytometry, acknowledging that any may be subject to modification if other disease-defining characteristics emerge.
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Requirements to assign myeloid lineage in MPAL
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Marker option 1 | |
Demonstrate expression of Myeloperoxidase (MPO) | Myeloperoxidase expression alone may be sufficient to establish myeloid lineage, but be aware of the limitations: (1) intensity should be at least half of that of mature neutrophils in at least of proportion of cells measured by the same method; (2) there are circumstances where judgement is required (see notes). |
Marker option 2 | |
Demonstrate clear evidence of monocytic lineage | If MPO is not demonstrated then myeloid lineage may still be assigned through demonstration of monocytic features. This can be assigned by the detection of at least two of the following features: By flow cytometry: CD11c, CD14, CD64; by other approaches: raised lysozyme in serum or urine or non-specific esterase in malignant cells (enzyme cytochemistry) |
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Requirements to assign myeloid lineage in MPAL
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