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|colspan="1" style = "font-size:90%; color:black; background:#ddeee1"|'''Mixed Phenotype Acute Leukaemia (MPAL)
|colspan="1" style = "font-size:90%; color:black; background: #a3c2c2"|'''Mixed Phenotype Acute Leukaemia (MPAL)'''
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<span style="font-size:90%;>'''Background''' MPAL requires a diagnosis of acute leukaemia (>20% blast cells) but in which differentiation does not occur along a single lineage. This diagnosis is uncommon (2-3% of acute leukaemia).</span>
<span style="font-size:90%;>'''Background''' MPAL requires a diagnosis of acute leukaemia (>20% blast cells) but in which differentiation occurs along a more than one lineage lineage. This diagnosis is uncommon (2-3% of acute leukaemia).</span>


<span style="font-size:90%;">Flow cytometry provides initial evidence of MPAL. However conclusions may subsequently be modified (e.g. by results of immunohistochemistry, cytogenetics, or genetics). It is important that the provisional nature of flow cytometry assignment of MPAL is acknowledged.</br></br></span>
<span style="font-size:90%;">Flow cytometry provides initial evidence of MPAL. However conclusions may subsequently be modified (e.g. by results of immunohistochemistry, cytogenetics, or genetics). It is important that the provisional nature of flow cytometry assignment of MPAL is acknowledged.</br></br></span>


<span style="font-size:90%;">'''Types and frequency of MPAL types'''</span></br>
<span style="font-size:90%;">'''Types and frequency of MPAL types'''</span></br>
<span style="font-size:90%;">''Initial assignment'':</span></br>
<span style="font-size:90%;">(1) MPAL with features of Myeloid and B-lineage (MPAL M/B) (>50% cases)</br></span>
<span style="font-size:90%;">(1) MPAL with features of Myeloid and B-lineage (MPAL M/B) (>50% cases)</br></span>
<span style="font-size:90%;">(2) MPAL with features of Myeloid and T-lineage (MPAL M/T) (>33% cases)</br></span>
<span style="font-size:90%;">(2) MPAL with features of Myeloid and T-lineage (MPAL M/T) (>33% cases)</br></span>
<span style="font-size:90%;">(3) MPAL with combinations: MPAL B/T (rare) or B/T/M (very rare)</br></span></br>
<span style="font-size:90%;">(3) MPAL with combinations: MPAL B/T (rare) or B/T/M (very rare)</br></span></br>
<span style="font-size:90%;">Following further analysis cases may be assigned additionally as:</span></br>
<span style="font-size:90%;">''Following further analysis cases may be more specifically assigned:''</span></br>
:<span style="font-size:90%;">MPAL with t(9;22) (q34.1;q11.2); BCR-ABL1;</span></br>
<span style="font-size:90%;">(4) MPAL with t(9;22) (q34.1;q11.2); BCR-ABL1;</span></br>
:<span style="font-size:90%;">MPAL with t(v;11q23.3); with KMT2A re-arrangement</span></br>
<span style="font-size:90%;">(5) MPAL with t(v;11q23.3); with KMT2A re-arrangement</span></br>
 


<span style="font-size:90%;">'''Mixed phenotype: biphenotypic pattern, bilineal pattern and blast cell number''' The blast population may express markers of the two separate lineages both on the same cell (bi-phenotypic pattern) in which case blast number must exceed 20%, alternatively the blast cells may have two lineages that co-exist (bi-lineal pattern) in which case the combined blast cell number must exceed 20%.</span>
<span style="font-size:90%;">'''Mixed phenotype: biphenotypic pattern, bilineal pattern and blast cell number''' The blast population may express markers of the two separate lineages both on the same cell (bi-phenotypic pattern) in which case blast number must exceed 20%, alternatively the blast cells may have two lineages that co-exist (bi-lineal pattern) in which case the combined blast cell number must exceed 20%.</span>


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!colspan="2" style = "background:palegrey; border:solid"|'''<span style="font-size:90%;">'''Criteria to assign myeloid lineage'''</span></br>
!colspan="2" style = "background:#bcd4e6;border:solid; font-size:90%"|<span style="font-size:90%;">'''1. Criteria to assign myeloid lineage'''</span></br>
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!colspan="2" style = "background:white;border:solid; font-size:90%;"|The case should have '''lineage-defining features''' of myeloid maturation. </br>[[Flow Cytometry:Myeloid lineage assignment in MPAL|Click here to review criteria for myeloid lineage assignment based on lineage-defining features]]</br></br>'''Note:''' myeloid-associated lineage markers cannot be contribute to myeloid lineage assignment in MPAL.
!colspan="2" style = "background:white;border:solid; font-size:90%;"|The case should have '''lineage-defining features''' of myeloid maturation. </br>[[Flow Cytometry:Myeloid lineage assignment in MPAL|Click here to review criteria for myeloid lineage assignment based on lineage-defining features]]</br></br>'''Note:''' myeloid-associated lineage markers cannot be contribute to myeloid lineage assignment in MPAL.
|-
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!colspan="2" style = "background:palegrey;border:solid; font-size:90%"|'''Criteria to assign B-lymphoid lineage'''
!colspan="2" style = "background:#bcd4e6;border:solid; font-size:90%"|<span style="font-size:90%;">'''Criteria to assign B-lymphoid lineage'''</span></br>
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!colspan="2" style = "background:white;border:solid; font-size:90%;"|
!colspan="2" style = "background:white;border:solid; font-size:90%;"|The case should have '''lineage-defining features''' of B-lymphoid maturation.</br>[[Flow Cytometry:B-lymphoid lineage assignment in MPAL|Click here to review criteria for B-lymphoid lineage assignment in MPAL]]</br></br>'''Note''' Where T-lineage is also considered, the lineage value of [[CD79a]] is reduced so should not be considered in the lineage assignment.</br>
<span style="font-size:90%;">|colspan="2" style = "font-size:90%; color:black;"|The case has '''lineage-defining features''' of B-lymphoid maturation. This allows B-lymphoid lineage to be defined in MPAL</br>[[Flow Cytometry:B-lymphoid lineage assignment in MPAL|Click here to review criteria for B-lymphoid lineage assignment in MPAL]]</br></br>'''Note''' Where T-lineage is also considered the diagnostic value of CD79A is reduced so should not be considered in the lineage assignment.</br>
|-</span></br>
 
<span style="font-size:90%;">CD4 may have the same pattern as CD5 but is not formally included in the definition</span>
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!colspan="2" style = "background:#bcd4e6;border:solid; font-size:90%"|<span style="font-size:90%;">'''Criteria to assign T-lymphoid lineage'''</span></br>
 
 
<span style="font-size:90%>To diagnose MPAL, the leukaemia should meet '''at least two of the three criteria''' below:
<span id="anchor_0">‎</span>.
<div style="width: 95%; border: 1px solid black; font-size:100%">
{| class="wikitable" style="color:black; background-color:white;" cellpadding="0"
!colspan="2" style = "font-size:90%; color:black; background:palegrey; border:solid"|'''Criteria to assign myeloid lineage'''
|-
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|colspan="2" style = "font-size:90%; color:black;"|The case has '''lineage-defining features''' of myeloid maturation. This allows myeloid lineage to be defined in MPAL</br>[[Flow Cytometry:Myeloid lineage assignment in MPAL|Click here to review criteria for myeloid lineage assignment based on lineage-defining features]]</br></br>'''Note:''' myeloid-associated lineage markers cannot be contribute to myeloid lineage assignment in MPAL.
!colspan="2" style = "background:white;border:solid; font-size:90%;"|The case should have '''lineage-defining features''' of T-lymphoid maturation.</br>[[Flow Cytometry:T-Lymphoid lineage assignment in MPAL|Click here to review criteria for T-lymphoid lineage assignment in MPAL]]</br>
|-
!colspan="2" style = "font-size:90%; color:black; background:palegrey; border:solid" |'''Criteria to assign B-lymphoid lineage'''
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|colspan="2" style = "font-size:90%; color:black;"|The case has '''lineage-defining features''' of B-lymphoid maturation. This allows B-lymphoid lineage to be defined in MPAL</br>[[Flow Cytometry:B-lymphoid lineage assignment in MPAL|Click here to review criteria for B-lymphoid lineage assignment in MPAL]]</br></br>'''Note''' Where T-lineage is also considered the diagnostic value of CD79A is reduced so should not be considered in the lineage assignment.</br>
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!colspan="2" style = "font-size:90%; color:black; background:palegrey; border:solid" |colspan="2" style = "font-size:90%; color:black;"|[[Flow Cytometry:T-Lymphoid lineage assignment in MPAL|Click here to review criteria for T-lymphoid lineage assignment in MPAL]]
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Consider also:
<span style="font-size:90%;">'''Consider also:'''</br></br>The most important alternative diagnosis occurs in cases of My/T phenotype where ETP-ALL should specifically be considered.</br>
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Latest revision as of 13:34, 18 January 2024

Mixed Phenotype Acute Leukaemia (MPAL)


Background MPAL requires a diagnosis of acute leukaemia (>20% blast cells) but in which differentiation occurs along a more than one lineage lineage. This diagnosis is uncommon (2-3% of acute leukaemia).

Flow cytometry provides initial evidence of MPAL. However conclusions may subsequently be modified (e.g. by results of immunohistochemistry, cytogenetics, or genetics). It is important that the provisional nature of flow cytometry assignment of MPAL is acknowledged.


Types and frequency of MPAL types
Initial assignment:
(1) MPAL with features of Myeloid and B-lineage (MPAL M/B) (>50% cases)
 (2) MPAL with features of Myeloid and T-lineage (MPAL M/T) (>33% cases)
 (3) MPAL with combinations: MPAL B/T (rare) or B/T/M (very rare)

Following further analysis cases may be more specifically assigned:
(4) MPAL with t(9;22) (q34.1;q11.2); BCR-ABL1;
(5) MPAL with t(v;11q23.3); with KMT2A re-arrangement


Mixed phenotype: biphenotypic pattern, bilineal pattern and blast cell number The blast population may express markers of the two separate lineages both on the same cell (bi-phenotypic pattern) in which case blast number must exceed 20%, alternatively the blast cells may have two lineages that co-exist (bi-lineal pattern) in which case the combined blast cell number must exceed 20%.


1. Criteria to assign myeloid lineage
The case should have lineage-defining features of myeloid maturation.
Click here to review criteria for myeloid lineage assignment based on lineage-defining features

Note: myeloid-associated lineage markers cannot be contribute to myeloid lineage assignment in MPAL.
Criteria to assign B-lymphoid lineage
The case should have lineage-defining features of B-lymphoid maturation.
Click here to review criteria for B-lymphoid lineage assignment in MPAL

Note Where T-lineage is also considered, the lineage value of CD79a is reduced so should not be considered in the lineage assignment.
Criteria to assign T-lymphoid lineage
The case should have lineage-defining features of T-lymphoid maturation.
Click here to review criteria for T-lymphoid lineage assignment in MPAL

Consider also:

The most important alternative diagnosis occurs in cases of My/T phenotype where ETP-ALL should specifically be considered.

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