Acute undifferentiated leukaemia
Haematolymphoid Tumours (WHO Classification, 5th ed.)
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Primary Author(s)*
Amelia Nakanishi, MD and Shashi Shetty, PhD
Cancer Category / Type
Hematologic malignancy/ Acute leukemia
Cancer Sub-Classification / Subtype
Acute Leukemias of Ambiguous Lineage (WHO 2017)/ Acute Undifferentiated Leukemia (AUL)
Definition / Description of Disease
An acute leukemia with blasts that are immunophenotypically ambiguous for any one hematopoietic lineage. AUL is a diagnosis of exclusion that is incompatible with the presence of features that meet the criteria for inclusion in any of the other AML groups (i.e. AML with Recurrent Genetic Abnormalities, AML with Myelodysplasia-Related Changes, or Therapy-Related Myeloid Neoplasms).
To support an undifferentiated phenotype, AUL requires an immunophenotypic work up that “excludes unusual lineages such as plasmacytoid dendritic cell precursors, natural killer precursors, basophils, and non-hematologic cells”[1].
Synonyms / Terminology
Blast cell leukemia, stem cell leukemia, stem cell acute leukemia, undifferentiated leukemia.
Epidemiology / Prevalence
Very rare; precise frequency unknown.
Clinical Features
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| Signs and Symptoms | EXAMPLE: Asymptomatic (incidental finding on complete blood counts)
EXAMPLE: B-symptoms (weight loss, fever, night sweats) EXAMPLE: Fatigue EXAMPLE: Lymphadenopathy (uncommon) |
| Laboratory Findings | EXAMPLE: Cytopenias
EXAMPLE: Lymphocytosis (low level) |
editHAEM5 Conversion NotesContent Update To WHO 5th Edition Classification Is In Process; Content Below is Based on WHO 4th Edition ClassificationIn one study of 16 cases of adults with AUL, the median age was 63 years (range: 24-84 years) and patients could achieve clinical remission after allogeneic stem cell transplantation[2]. In previous studies that weakly suggest ALL induction regimens over AML induction regimens, there may be selection bias in the patients who were well enough to be transplant candidates[3].
In children, based on limited clinical information in the literature, AUL has been associated with a poor prognosis[4].
Sites of Involvement
Bone marrow and peripheral blood. AUL is so rare, it is unknown if there is a pattern of other sites of involvement.
Morphologic Features
AUL blast morphology is bland and non-specific. Cytoplasmic granulation and disease defining morphology are absent.
Immunophenotype
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| Finding | Marker |
|---|---|
| Positive (universal) | EXAMPLE: CD1 |
| Positive (subset) | EXAMPLE: CD2 |
| Negative (universal) | EXAMPLE: CD3 |
| Negative (subset) | EXAMPLE: CD4 |
editHAEM5 Conversion NotesContent Update To WHO 5th Edition Classification Is In Process; Content Below is Based on WHO 4th Edition ClassificationPer WHO 2017, AUL blasts should express no more than one membrane marker for any lineage.
Positive (universal) Precursor stage: HLA-DR, CD34, and/or CD38, CD117, CD133 [5] Positive (subset) TdT CD7 (weak positivity) see below.
Negative (universal) Myeloid: MPO Monocytic: NSE, CD11c, Cd14, CD64, lysozyme, Cd4, CD11b, CD36, NG2 homologue
T cell: cCD3
B cell: cCD22, cCD79a, strong CD19
Megakaryocytic: CD41, CD61, CD42, CD235a
Negative (subset) NA Additional Description: Blasts are generally positive for HLA-DR, CD34, and/or CD38.
-CD7 positivity is associated with T cells, but can also be seen in some CD34+ hematopoietic stem cells and is not unexpected in a stem cell leukemia[1].
-See HAEM4:Acute Leukemias of Ambiguous Lineage for assigning lineage assignment.
Chromosomal Rearrangements (Gene Fusions)
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| Chromosomal Rearrangement | Genes in Fusion (5’ or 3’ Segments) | Pathogenic Derivative | Prevalence | Diagnostic Significance (Yes, No or Unknown) | Prognostic Significance (Yes, No or Unknown) | Therapeutic Significance (Yes, No or Unknown) | Notes |
|---|---|---|---|---|---|---|---|
| EXAMPLE: t(9;22)(q34;q11.2) | EXAMPLE: 3'ABL1 / 5'BCR | EXAMPLE: der(22) | EXAMPLE: 20% (COSMIC)
EXAMPLE: 30% (add reference) |
Yes | No | Yes | EXAMPLE:
The t(9;22) is diagnostic of CML in the appropriate morphology and clinical context (add reference). This fusion is responsive to targeted therapy such as Imatinib (Gleevec) (add reference). |
editHAEM5 Conversion NotesContent Update To WHO 5th Edition Classification Is In Process; Content Below is Based on WHO 4th Edition ClassificationNA
editHAEM5 Conversion NotesPlease incorporate this section into the relevant tables found in:
- Chromosomal Rearrangements (Gene Fusions)
- Individual Region Genomic Gain/Loss/LOH
- Characteristic Chromosomal Patterns
- Gene Mutations (SNV/INDEL)
There is evidence that the genes associated with poor prognosis in acute leukemias, BAALC, ERG, and MN1, are also overexpressed in AUL[1].
Individual Region Genomic Gain / Loss / LOH
Put your text here and fill in the table (Instructions: Includes aberrations not involving gene fusions. Can include references in the table. Can refer to CGC workgroup tables as linked on the homepage if applicable. Do not delete table.)
| Chr # | Gain / Loss / Amp / LOH | Minimal Region Genomic Coordinates [Genome Build] | Minimal Region Cytoband | Diagnostic Significance (Yes, No or Unknown) | Prognostic Significance (Yes, No or Unknown) | Therapeutic Significance (Yes, No or Unknown) | Notes |
|---|---|---|---|---|---|---|---|
| EXAMPLE:
7 |
EXAMPLE: Loss | EXAMPLE:
chr7:1- 159,335,973 [hg38] |
EXAMPLE:
chr7 |
Yes | Yes | No | EXAMPLE:
Presence of monosomy 7 (or 7q deletion) is sufficient for a diagnosis of AML with MDS-related changes when there is ≥20% blasts and no prior therapy (add reference). Monosomy 7/7q deletion is associated with a poor prognosis in AML (add reference). |
| EXAMPLE:
8 |
EXAMPLE: Gain | EXAMPLE:
chr8:1-145,138,636 [hg38] |
EXAMPLE:
chr8 |
No | No | No | EXAMPLE:
Common recurrent secondary finding for t(8;21) (add reference). |
editHAEM5 Conversion NotesContent Update To WHO 5th Edition Classification Is In Process; Content Below is Based on WHO 4th Edition ClassificationNA
Characteristic Chromosomal Patterns
Put your text here (EXAMPLE PATTERNS: hyperdiploid; gain of odd number chromosomes including typically chromosome 1, 3, 5, 7, 11, and 17; co-deletion of 1p and 19q; complex karyotypes without characteristic genetic findings; chromothripsis. Do not delete table.)
| Chromosomal Pattern | Diagnostic Significance (Yes, No or Unknown) | Prognostic Significance (Yes, No or Unknown) | Therapeutic Significance (Yes, No or Unknown) | Notes |
|---|---|---|---|---|
| EXAMPLE:
Co-deletion of 1p and 18q |
Yes | No | No | EXAMPLE:
See chromosomal rearrangements table as this pattern is due to an unbalanced derivative translocation associated with oligodendroglioma (add reference). |
editHAEM5 Conversion NotesContent Update To WHO 5th Edition Classification Is In Process; Content Below is Based on WHO 4th Edition ClassificationAUL is associated with a high rate of chromosomal abnormalities, but have no characteristic abnormalities[2].
Gene Mutations (SNV / INDEL)
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| Gene; Genetic Alteration | Presumed Mechanism (Tumor Suppressor Gene [TSG] / Oncogene / Other) | Prevalence (COSMIC / TCGA / Other) | Concomitant Mutations | Mutually Exclusive Mutations | Diagnostic Significance (Yes, No or Unknown) | Prognostic Significance (Yes, No or Unknown) | Therapeutic Significance (Yes, No or Unknown) | Notes |
|---|---|---|---|---|---|---|---|---|
| EXAMPLE: TP53; Variable LOF mutations
EXAMPLE: EGFR; Exon 20 mutations EXAMPLE: BRAF; Activating mutations |
EXAMPLE: TSG | EXAMPLE: 20% (COSMIC)
EXAMPLE: 30% (add Reference) |
EXAMPLE: IDH1 R123H | EXAMPLE: EGFR amplification | EXAMPLE: Excludes hairy cell leukemia (HCL) (add reference).
|
Note: A more extensive list of mutations can be found in cBioportal (https://www.cbioportal.org/), COSMIC (https://cancer.sanger.ac.uk/cosmic), ICGC (https://dcc.icgc.org/) and/or other databases. When applicable, gene-specific pages within the CCGA site directly link to pertinent external content.
editHAEM5 Conversion NotesContent Update To WHO 5th Edition Classification Is In Process; Content Below is Based on WHO 4th Edition ClassificationPHF6 a tumor suppressor gene may have implications in AUL though the evidence is limited.
Other Mutations
NA
Epigenomic Alterations
Unknown
Genes and Main Pathways Involved
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| Gene; Genetic Alteration | Pathway | Pathophysiologic Outcome |
|---|---|---|
| EXAMPLE: BRAF and MAP2K1; Activating mutations | EXAMPLE: MAPK signaling | EXAMPLE: Increased cell growth and proliferation |
| EXAMPLE: CDKN2A; Inactivating mutations | EXAMPLE: Cell cycle regulation | EXAMPLE: Unregulated cell division |
| EXAMPLE: KMT2C and ARID1A; Inactivating mutations | EXAMPLE: Histone modification, chromatin remodeling | EXAMPLE: Abnormal gene expression program |
editHAEM5 Conversion NotesContent Update To WHO 5th Edition Classification Is In Process; Content Below is Based on WHO 4th Edition ClassificationOverexpression of BAALC, ERG, and MN1[1].
Genetic Diagnostic Testing Methods
Morphology, immunohistochemistry, cytochemistry, flow cytometry, cytogenetics, and next generation sequencing.
Familial Forms
Unknown
Additional Information
Although AUL and AML with minimal differentiation are both rare diagnoses, they have similar patient demographics and clinical courses. AUL and AML with minimal differentiation have different molecular abnormalities[2].
Links
References
(use the "Cite" icon at the top of the page) (Instructions: Add each reference into the text above by clicking on where you want to insert the reference, selecting the “Cite” icon at the top of the page, and using the “Automatic” tab option to search such as by PMID to select the reference to insert. The reference list in this section will be automatically generated and sorted. If a PMID is not available, such as for a book, please use the “Cite” icon, select “Manual” and then “Basic Form”, and include the entire reference.)
- ↑ 1.0 1.1 1.2 1.3 Borowitz MJ, et al., (2017). Acute leukaemias of ambiguous lineage, in World Health Organization Classification of Tumours of Haematopoietic and Lymphoid Tissues, Revised 4th edition. Swerdlow SH, Campo E, Harris NL, Jaffe ES, Pileri SA, Stein H, Thiele J, Arber DA, Hasserjian RP, Le Beau MM, Orazi A, and Siebert R, Editors. IARC Press: Lyon, France, p182.
- ↑ 2.0 2.1 2.2 Heesch, Sandra; et al. (2013). "Acute leukemias of ambiguous lineage in adults: molecular and clinical characterization". Annals of Hematology. 92 (6): 747–758. doi:10.1007/s00277-013-1694-4. ISSN 1432-0584. PMID 23412561.
- ↑ Weinberg, Olga K.; et al. (2019). "Clinical, immunophenotypic, and genomic findings of acute undifferentiated leukemia and comparison to acute myeloid leukemia with minimal differentiation: a study from the bone marrow pathology group". Modern Pathology: An Official Journal of the United States and Canadian Academy of Pathology, Inc. 32 (9): 1373–1385. doi:10.1038/s41379-019-0263-3. ISSN 1530-0285. PMID 31000771.
- ↑ Lee, Hyun Gyung; et al. (2019). "Biphenotypic acute leukemia or acute leukemia of ambiguous lineage in childhood: clinical characteristics and outcome". Blood Research. 54 (1): 63–73. doi:10.5045/br.2019.54.1.63. ISSN 2287-979X. PMC 6439300. PMID 30956966.
- ↑ Hoffman R, et al., (2018) Hematology, basic principles and practice, 7th edition. Elsevier: Philadelphia. (clinical key excerpt)
Notes
*Primary authors will typically be those that initially create and complete the content of a page. If a subsequent user modifies the content and feels the effort put forth is of high enough significance to warrant listing in the authorship section, please contact the CCGA coordinators (contact information provided on the homepage). Additional global feedback or concerns are also welcome. *Citation of this Page: “Acute undifferentiated leukaemia”. Compendium of Cancer Genome Aberrations (CCGA), Cancer Genomics Consortium (CGC), updated 09/1/2024, https://ccga.io/index.php/HAEM5:Acute_undifferentiated_leukaemia.