MPAL: Difference between revisions
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<div class="mw-collapsible mw-collapsed" data-expandtext="Click for explanation" data-collapsetext="Hide explanation"> | <div class="mw-collapsible mw-collapsed" data-expandtext="Click for explanation" data-collapsetext="Hide explanation"> | ||
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<span style="font-size:80%; text-align:left;"></br>This is a difficult area where the diagnosis is | <span style="font-size:80%; text-align:left;"></br>This is a difficult area where the diagnosis of acute leukaemia is suspected but no criteria for lineage assignment can be made i.e. the cases do not meet any of the criteria for myeloid, B-lymphoid, or T-lymphoid lineage given above. An important aspect of this group is to exclude the possibility of rare entities that can mimic AML: these include non-haemaotopoietic neoplasm and blastic plasma cell dendritic neoplasm.</br> | ||
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Revision as of 15:14, 27 July 2023
Final lineage in MPAL requires integration of additional molecular features, so assigments made by flow should be regarded as "provisional" pending full molecular assessment.
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Requirements to assign myeloid lineage in MPAL
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Pption 1 | |
Myeloperoxidase (MPO) | This marker alone is sufficient to establish myeloid lineage provided it meets the intensity definition - intensity should be at least half of that of mature neutrophils in at least of proportion of cells. |
Option 2 | |
If MPO does not meet criteria for myeloid lineage, then myeloid lineage may still be assigned through demonstration of monocytic lineage. 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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Lineage assignments 2 - defining B-lymphoid lineage in MPAL
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Marker combination 1 | |
Required Strong expression of CD19 | To meet the definition of "strong" the expression intensity must exceed that of 50% of normal B lymphocytes |
In addition: CD10, CD22, or CD79a | If CD19 is strong then B-lineage can be assigned if there is at least ONE of these additional markers |
Marker combination 2 | |
Required Weak expression of CD19 | To meet the definition of "weak" the expression intensity must be less than that of 50% of normal B lymphocytes |
In addition: CD10, CD22, or CD79a | If CD19 is strong then B-lineage can be assigned if there is at least TWO of these additional markers |
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Lineage assignments 3 - defining T-lymphoid lineage in MPAL
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Marker requirement | |
Either CD3 surface or cytoplasm (strong) | To meet the definition of "strong" the expression intensity must exceed that of 50% of normal T lymphocytes |
Or CD3 by immunocytochemistry (strong) | For immunohistochemistry it is important a non-zeta chain reagent is used |
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Lineage assignments 3 - defining undifferentiated leukaemia
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Marker combination 1 | |
Required Strong expression of CD19 | To meet the definition of "strong" the expression intensity must exceed that of 50% of normal B lymphocytes |
In addition: CD10, CD22, or CD79a | If CD19 is strong then B-lineage can be assigned if there is at least ONE of these additional markers |
Marker combination 2 | |
Required Weak expression of CD19 | To meet the definition of "weak" the expression intensity must be less than that of 50% of normal B lymphocytes |
In addition: CD10, CD22, or CD79a | If CD19 is strong then B-lineage can be assigned if there is at least TWO of these additional markers |