Flow cytometry:ETP-ALL: Difference between revisions
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<span style="font-size:90%;">'''Note''' CD7 is consistently positive in ETP-ALL and does not count as a stem cell antigen in this context</span> | <span style="font-size:90%;">'''Note''' CD7 is consistently positive in ETP-ALL and does not count as a stem cell antigen in this context</span> | ||
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!colspan="2" style = "background:palegrey;border:solid"|'''Requirement 2: Non-expressed antigens''' | !colspan="2" style = "background:palegrey;border:solid; font-size:90%"|'''Requirement 2: Non-expressed antigens''' | ||
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!colspan="2" style = "background:white;border:solid; font-size:90%;"| | !colspan="2" style = "background:white;border:solid; font-size:90%;"|Required absence: CD3, CD1a and CD8 (<5% of blasts) | ||
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!colspan=" | !colspan="2" style = "background:white;border:solid; font-size:90%;"|Criteria for BPCN (set 2) | ||
!colspan="1" style = "background:white;border:solid; font-size:90%;"|'''[[CD123]] not expressed''' but at least three of CD303, CD304, TCF4, TCL1 are expressed | !colspan="1" style = "background:white;border:solid; font-size:90%;"|'''[[CD123]] not expressed''' but at least three of CD303, CD304, TCF4, TCL1 are expressed | ||
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Revision as of 17:00, 17 January 2024
| Early T precursor acute lympholastic leukaemia (ETP-ALL) |
The immunophenotype of ETP-ALL requires careful consideration – this reflects that the condition was identified using gene expression profiling rather than by immunophenotype. Using immunophenotype to establish the diagnosis is therefore challenging and may underestimate the number of true cases.* and may not be easily separated from ALAL T/my or T-ALL
To diagnose ETP-ALL the cells need to meet specific criteria. These are given in the table below:
| Requirement 1: Expressed antigens | ||
|---|---|---|
| 1. T-lineage should be demonstrated: (may be heterogenous but should be expressed by ≥25% of blasts)Assignment of T-Lymphoid lineage in ETP-ALL 2. One or more myeloid antigen (CD11b, CD13, CD33, CD65, CD117) and/or stem cell antigens (CD34, HLA-DR) should be present | ||
| Requirement 2: Non-expressed antigens | ||
| Required absence: CD3, CD1a and CD8 (<5% of blasts) | ||
| Criteria for BPCN (set 2) | CD123 not expressed but at least three of CD303, CD304, TCF4, TCL1 are expressed | |
| 1. The immunophenotype of the blast cells should be consistent with their "primitive" nature |
| Requirement 1: Expressed antigens |
|---|
|
1. T-lineage should be demonstrated: (may be heterogenous but should be expressed by ≥25% of blasts)Assignment of T-Lymphoid lineage in ETP-ALL |
| Requirement 2: Non-expressed antigens |
|
*Required absence: CD3, CD1a and CD8 (<5% of blasts)
|
| NOTES |
|
The ETP-ALL immunophenotype may also be established by immunohistochemistry.
Distinction from mixed-phenotype acute leukaemia (MPAL) requires that MPO is not expressed - in this context of ETP-ALL the WHO advocate a threshold of <3% to define negative myeloperoxidase expression (by cytochemistry or flow cytometry). This threshold is different from that of T/myeloid MPAL so may not be optimal but is retained at present.
- T-ALL cases that have an immunophenotype similar to ETP-ALL but where CD5 is expressed (≥75% of blasts) may be designated as “near-ETP-ALL”, but the clinical implications of such a designation remain unclear.