HAEM5:Adult T-cell leukaemia/lymphoma

Haematolymphoid Tumours (WHO Classification, 5th ed.)

editContent Update To WHO 5th Edition Classification Is In Process; Content Below is Based on WHO 4th Edition Classification

This page was converted to the new template on 2023-12-07. The original page can be found at HAEM4:Adult T-cell Leukemia/Lymphoma.

(General Instructions – The focus of these pages is the clinically significant genetic alterations in each disease type. This is based on up-to-date knowledge from multiple resources such as PubMed and the WHO classification books. The CCGA is meant to be a supplemental resource to the WHO classification books; the CCGA captures in a continually updated wiki-stye manner the current genetics/genomics knowledge of each disease, which evolves more rapidly than books can be revised and published. If the same disease is described in multiple WHO classification books, the genetics-related information for that disease will be consolidated into a single main page that has this template (other pages would only contain a link to this main page). Use HUGO-approved gene names and symbols (italicized when appropriate), HGVS-based nomenclature for variants, as well as generic names of drugs and testing platforms or assays if applicable. Please complete tables whenever possible and do not delete them (add N/A if not applicable in the table and delete the examples); to add (or move) a row or column in a table, click nearby within the table and select the > symbol that appears. Please do not delete or alter the section headings. The use of bullet points alongside short blocks of text rather than only large paragraphs is encouraged. Additional instructions below in italicized blue text should not be included in the final page content. Please also see Author_Instructions and FAQs as well as contact your Associate Editor or Technical Support.)

Primary Author(s)*

Prasad R. Kopparapu, PhD and Ferrin C. Wheeler, PhD, FACMG

Vanderbilt University Medical Center

WHO Classification of Disease

Structure	Disease
Book	Haematolymphoid Tumours (5th ed.)
Category	T-cell and NK-cell lymphoid proliferations and lymphomas
Family	Mature T-cell and NK-cell neoplasms
Type	Mature T-cell and NK-cell leukaemias
Subtype(s)	Adult T-cell leukaemia/lymphoma

Definition / Description of Disease

Adult T-cell Leukemia/Lymphoma (ATLL) is a systemic, aggressive T-cell malignancy cause by chronic infection of human T lymphotropic virus 1 (HTLV-1) with poor prognosis.

Synonyms / Terminology

Adult T-cell leukemia, Adult T-cell lymphoma, HTLV-1 associated adult T-cell leukemia-lymphoma.

Epidemiology / Prevalence

ATLL is endemic in many parts of Southwestern Japan, the Caribbean basin, Sub-Saharan Africa, South America, Romania, Northern Iran, parts of the Middle East and Australo-Melanesia.

ATLL occurs only in adults between 30 to 90 years of age with an average age of 58 years. The male-to-female ratio is 1.5:1.

Transmission occurs through breast milk, sexual fluids, peripheral blood and blood products.

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)

editv4:Clinical Features

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ATLL is classified into four clinical subtypes: Acute, Lymphoma, Chronic and Smoldering.

Acute: Most common type (65% of patients) with elevated WBC count, skin rash and generalized lymphadenopathy, hypercalcemia, hepatosplenomegaly, elevated LDH and frequent opportunistic infections like pneumocystis jirovecii pneumonia and strongyloidiasis.

Lymphoma: The lymphomatous variant is characterized by lymphadenopathy, absence of lymphocytosis, possible extranodal lesions with minimal peripheral blood involvement and less frequent hypercalcemia.

Chronic: The chronic variant can progress to acute or lymphomatous subtype. This variant manifests with lymphocytosis and exfoliative skin lesions.  Atypical lymphocytes are fewer in number in peripheral blood. There can be mild hepatosplenomegaly and lymphadenopathy. Hypercalcemia is not observed, and no involvement of CNS, bone and gastrointestinal tract, and neither ascites nor pleural effusion.

Smoldering: This variant may also progress to the acute subtype upon long duration. This variant may present with skin or lung lesions. More than 5% circulating abnormal T-cell lymphocytes can be found in the absence of leukocytosis. No manifestation of hypercalcemia, hepatosplenomegaly or lymphadenopathy.

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Sites of Involvement

In addition to lymph node involvement, there is involvement in extranodal sites like spleen, skin, lung, liver, gastrointestinal tract and CNS, making this a systemic disease with peripheral blood involvement.

Morphologic Features

The morphological features of ATLL in skin include erythema, papules, and nodules based on macroscopic examination and perivascular infiltration of atypical lymphoid cells, diffuse infiltration of medium to large sized atypical lymphoid cells and infiltration of large atypical lymphoid cell as per histopathological observations.

Lymph node lesions present as pleomorphic small, medium and large cell types, anaplastic and an angioimmunoblastic T-cell lymphoma type.

Infiltration of atypical lymphoid cells with irregular or round nuclei is seen in the bone marrow cavity with detection of hypercalcemia.

In liver, infiltration of atypical medium to large sized lymphoid cells with irregular nuclei is seen.

Diffuse, pleomorphic and anaplastic type cells can infiltrate the stomach destroying the gastric glands.

In peripheral blood, “flower like” cells that have multilobed nucleus with basophilic cytoplasm can be observed by Giemsa staining.

Immunophenotype

In most patients, tumor cells exhibit phenotype of mature CD4+ T cells by expressing CD2, CD3, CD5, CD25, CD45RO, CD29, T-cell receptor αβ, FOXP3, CD52,  and HLA-DR.

Most cases are CD4+CD8-, but rarely, cases can be CD4-CD8+ or CD4+CD8+. A typical immunophenotype for ATLL is: CD2+, CD3+, CD4+, CD7-, CD8-, CD25+, CD30+/-, TCR αβ+.

Immunophenotypic characterization of CD3, CD4, CD7 , CD8, and CD25 are the minimum requirement for an ATLL diagnosis.

Finding	Marker
Positive (universal)	CD2, CD3, CD5, CD4, CCD4
Positive (subset)	CD8, CD4, CD30, FOXP3
Negative (universal)	CD7, CD8, TdT, TCL1, ALK1, B cell antigens, cytotoxic molecules
Negative (subset)	CD4,CD8, ALK

WHO Essential and Desirable Genetic Diagnostic Criteria

(Instructions: The table will have the diagnostic criteria from the WHO book autocompleted; remove any non-genetics related criteria. If applicable, add text about other classification systems that define this entity and specify how the genetics-related criteria differ.)

WHO Essential Criteria (Genetics)*
WHO Desirable Criteria (Genetics)*
Other Classification

*Note: These are only the genetic/genomic criteria. Additional diagnostic criteria can be found in the WHO Classification of Tumours.

Related Terminology

(Instructions: The table will have the related terminology from the WHO autocompleted.)

Acceptable
Not Recommended

Gene Rearrangements

Put your text here and fill in the table (Instructions: Details on clinical significance such as prognosis and other important information can be provided in the notes section. Please include references throughout the table. Do not delete the table.)

Driver Gene	Fusion(s) and Common Partner Genes	Molecular Pathogenesis	Typical Chromosomal Alteration(s)	Prevalence -Common >20%, Recurrent 5-20% or Rare <5% (Disease)	Diagnostic, Prognostic, and Therapeutic Significance - D, P, T	Established Clinical Significance Per Guidelines - Yes or No (Source)	Clinical Relevance Details/Other Notes
EXAMPLE: ABL1	EXAMPLE: BCR::ABL1	EXAMPLE: The pathogenic derivative is the der(22) resulting in fusion of 5’ BCR and 3’ABL1.	EXAMPLE: t(9;22)(q34;q11.2)	EXAMPLE: Common (CML)	EXAMPLE: D, P, T	EXAMPLE: Yes (WHO, NCCN)	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). BCR::ABL1 is generally favorable in CML (add reference).
EXAMPLE: CIC	EXAMPLE: CIC::DUX4	EXAMPLE: Typically, the last exon of CIC is fused to DUX4. The fusion breakpoint in CIC is usually intra-exonic and removes an inhibitory sequence, upregulating PEA3 genes downstream of CIC including ETV1, ETV4, and ETV5.	EXAMPLE: t(4;19)(q25;q13)	EXAMPLE: Common (CIC-rearranged sarcoma)	EXAMPLE: D		EXAMPLE: DUX4 has many homologous genes; an alternate translocation in a minority of cases is t(10;19), but this is usually indistinguishable from t(4;19) by short-read sequencing (add references).
EXAMPLE: ALK	EXAMPLE: ELM4::ALK Other fusion partners include KIF5B, NPM1, STRN, TFG, TPM3, CLTC, KLC1	EXAMPLE: Fusions result in constitutive activation of the ALK tyrosine kinase. The most common ALK fusion is EML4::ALK, with breakpoints in intron 19 of ALK. At the transcript level, a variable (5’) partner gene is fused to 3’ ALK at exon 20. Rarely, ALK fusions contain exon 19 due to breakpoints in intron 18.	EXAMPLE: N/A	EXAMPLE: Rare (Lung adenocarcinoma)	EXAMPLE: T		EXAMPLE: Both balanced and unbalanced forms are observed by FISH (add references).
EXAMPLE: ABL1	EXAMPLE: N/A	EXAMPLE: Intragenic deletion of exons 2–7 in EGFR removes the ligand-binding domain, resulting in a constitutively active tyrosine kinase with downstream activation of multiple oncogenic pathways.	EXAMPLE: N/A	EXAMPLE: Recurrent (IDH-wildtype Glioblastoma)	EXAMPLE: D, P, T

editv4:Chromosomal Rearrangements (Gene Fusions)

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Tandem duplications of  2q33.2 segments cause formation of CTLA4-CD28 and ICOS-CD28 fusion products that render prolonged co-stimulatory signals.

Chromosomal Rearrangement	Genes in Fusion (5’ or 3’ Segments)	Pathogenic Derivative	Prevalence
2q33.2 (Tandem Duplication)	5’ CTLA/3’CD28	der(2)	7%
2q33.2 (Tandem Duplication)	5’ICOS/3’CD28	der(2)	7%

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editv4:Clinical Significance (Diagnosis, Prognosis and Therapeutic Implications).

Please 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)

ATLL diagnosis can be made based on seropositivity for HTLV-1 and histologically and/or cytologically proven peripheral T cell lymphoma (PTCL). Diagnosis can also be made by quantifying proviral DNA loads (PVLs) in peripheral blood mononuclear cells using real time PCR. PVL of an infected person can range from 0.01 to 50% or higher. Other diagnostic criteria includes appropriate patient demographic information, hypercalcemia, skin lesions and a leukemic phase.

The prognosis of ATLL is largely dependent on the subtype. The acute and lymphomatous subtypes are aggressive, with a median survival of 6.2 months and 10.2 months, respectively. The less-aggressive chronic and smoldering subtypes have a median survival of approximately 4.5 years. Prognostic factors include clinical variant, age, serum calcium and LDH levels as well as detection of opportunistic infections of parasitic or viral types and p16 gene deletion and p53 mutation.

As ATLL is resistant to most chemotherapy, there is no standard chemotherapy regimen. High dose combination chemotherapy and bone marrow transplantation have been tried previously. Monoclonal antibody-based therapies against IL-2R (anti-Tac), CCR4 (mogamulizumab) and CD52 (alemtuzumab) have also been attempted along with arsenic trioxide, interferon α and zidovudine.

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Individual Region Genomic Gain/Loss/LOH

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Chr #	Gain, Loss, Amp, LOH	Minimal Region Cytoband and/or Genomic Coordinates [Genome Build; Size]	Relevant Gene(s)	Diagnostic, Prognostic, and Therapeutic Significance - D, P, T	Established Clinical Significance Per Guidelines - Yes or No (Source)	Clinical Relevance Details/Other Notes
EXAMPLE: 7	EXAMPLE: Loss	EXAMPLE: chr7	EXAMPLE: Unknown	EXAMPLE: D, P	EXAMPLE: 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 references).
EXAMPLE: 8	EXAMPLE: Gain	EXAMPLE: chr8	EXAMPLE: Unknown	EXAMPLE: D, P		EXAMPLE: Common recurrent secondary finding for t(8;21) (add references).
EXAMPLE: 17	EXAMPLE: Amp	EXAMPLE: 17q12; chr17:39,700,064-39,728,658 [hg38; 28.6 kb]	EXAMPLE: ERBB2	EXAMPLE: D, P, T		EXAMPLE: Amplification of ERBB2 is associated with HER2 overexpression in HER2 positive breast cancer (add references). Add criteria for how amplification is defined.

editv4:Genomic Gain/Loss/LOH

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ATLL with high number of chromosomal imbalances is associated with poor survival.

Chromosome Number	Gain/Loss/Amp/LOH	Region
1	Gain	1q
2	Gain	2p
3	Gain	3p
4	Gain	4q
6	Loss	6q
7	Gain	7p, 7q
9	Amp	9p
10	Loss	10p
13	Loss	13q
14	Gain	14q
16	Loss	16q
18	Loss	18p

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Characteristic Chromosomal or Other Global Mutational Patterns

Put your text here and fill in the table (Instructions: Included in this category are alterations such as 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; microsatellite instability; homologous recombination deficiency; mutational signature pattern; etc. Details on clinical significance such as prognosis and other important information can be provided in the notes section. Please include references throughout the table. Do not delete the table.)

Chromosomal Pattern	Molecular Pathogenesis	Prevalence - Common >20%, Recurrent 5-20% or Rare <5% (Disease)	Diagnostic, Prognostic, and Therapeutic Significance - D, P, T	Established Clinical Significance Per Guidelines - Yes or No (Source)	Clinical Relevance Details/Other Notes
EXAMPLE: Co-deletion of 1p and 18q	EXAMPLE: See chromosomal rearrangements table as this pattern is due to an unbalanced derivative translocation associated with oligodendroglioma (add reference).	EXAMPLE: Common (Oligodendroglioma)	EXAMPLE: D, P
EXAMPLE: Microsatellite instability - hypermutated		EXAMPLE: Common (Endometrial carcinoma)	EXAMPLE: P, T

editv4:Characteristic Chromosomal Aberrations / Patterns

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Cytogenetic studies show that ATLL often has a complex abnormal karyotype without a single distinct abnormality. Observed recurrent abnormalities include trisomy for 3, 7 or 21 and monosomy for X as well as deletion of Y and abnormalities of chromosome 6 and 14. Chromosome 14 rearrangements involving TCRA and TCRD at 14q11 and TCL1 at 14q32 have been documented. Frequent deletions in known fragile sites have been detected in over 500 patients.

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Gene Mutations (SNV/INDEL)

Put your text here and fill in the table (Instructions: This table is not meant to be an exhaustive list; please include only genes/alterations that are recurrent or common as well either disease defining and/or clinically significant. If a gene has multiple mechanisms depending on the type or site of the alteration, add multiple entries in the table. For clinical significance, denote associations with FDA-approved therapy (not an extensive list of applicable drugs) and NCCN or other national guidelines if applicable; Can also refer to CGC workgroup tables as linked on the homepage if applicable as well as any high impact papers or reviews of gene mutations in this entity. Details on clinical significance such as prognosis and other important information such as concomitant and mutually exclusive mutations can be provided in the notes section. Please include references throughout the table. Do not delete the table.)

Gene	Genetic Alteration	Tumor Suppressor Gene, Oncogene, Other	Prevalence - Common >20%, Recurrent 5-20% or Rare <5% (Disease)	Diagnostic, Prognostic, and Therapeutic Significance - D, P, T	Established Clinical Significance Per Guidelines - Yes or No (Source)	Clinical Relevance Details/Other Notes
EXAMPLE:EGFR	EXAMPLE: Exon 18-21 activating mutations	EXAMPLE: Oncogene	EXAMPLE: Common (lung cancer)	EXAMPLE: T	EXAMPLE: Yes (NCCN)	EXAMPLE: Exons 18, 19, and 21 mutations are targetable for therapy. Exon 20 T790M variants cause resistance to first generation TKI therapy and are targetable by second and third generation TKIs (add references).
EXAMPLE: TP53; Variable LOF mutations	EXAMPLE: Variable LOF mutations	EXAMPLE: Tumor Supressor Gene	EXAMPLE: Common (breast cancer)	EXAMPLE: P		EXAMPLE: >90% are somatic; rare germline alterations associated with Li-Fraumeni syndrome (add reference). Denotes a poor prognosis in breast cancer.
EXAMPLE: BRAF; Activating mutations	EXAMPLE: Activating mutations	EXAMPLE: Oncogene	EXAMPLE: Common (melanoma)	EXAMPLE: T

Note: A more extensive list of mutations can be found in cBioportal, COSMIC, and/or other databases. When applicable, gene-specific pages within the CCGA site directly link to pertinent external content.

editv4:Gene Mutations (SNV/INDEL)

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Over 10% of ATLL cases harbor mostly gain of function mutations. ATLL harbors multiple recurrent mutations in genes involved in the TCR-NF-κB pathway, tumor suppressors, transcription factors involved in cell growth and proliferation, apoptosis, and immune surveillance.

Gene	Mutation	Oncogene/Tumor Suppressor/Other	Presumed Mechanism (LOF/GOF/Other; Driver/Passenger)	Prevalence (COSMIC/TCGA/Other)
PLCG1		TCR – NF-κB Signaling	GOF
PKCB		TCR – NF-κB Signaling	GOF
CARD11		TCR – NF-κB Signaling	GOF
VAV1		TCR – NF-κB Signaling	GOF
CD237		TCR – NF-κB Signaling	GOF
RHOA		RAS-RAF-ERK pathway	GOF
IRF4		Transcription Factor	GOF
NOTCH1		Transcription Factor	GOF
FBXW7		Transcription Factor	GOF
STAT3		Transcription Factor	GOF
TNFAIP3/A20		TCR – NF-κB Signaling	LOF
NFKBIA/IκBα		TCR – NF-κB Signaling	LOF
TRAF3		TCR – NF-κB Signaling	LOF
CBLB		TCR – NF-κB Signaling	LOF
TP53		Tumor Suppressor	LOF
CDKN2		Tumor Suppressor	LOF
GATA3		Transcription Factor	LOF
EP300		Transcription Factor	LOF
FAS		Apoptosis	LOF
WWOX		Apoptosis	LOF
HLA-B		Immune Surveillance	LOF
B2M		Immune Surveillance	LOF
PD-L1		Immune Surveillance	Amplification

Other Mutations

Type	Gene/Region/Other
Concomitant Mutations	EXAMPLE: IDH1 R123H
Secondary Mutations	EXAMPLE: Trisomy 7
Mutually Exclusive	EXAMPLE: EGFR Amplification

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Epigenomic Alterations

Epigenetic alterations also result in dysregulated TCR/NF-κB signaling in ATLL. DNA hypermethylation of CpG islands is detected in 1/3^rd of all ATLL patients. As a result, genes involved in Cys2-His2 (C2H2) zinc finger genes and those encoding MHC class I molecules are silenced.

ATLL patients have high expression of polycomb repressive complex (PRC) 2 components like EZH2, its homolog EZH1 and H3K27 methylase causing accumulation of trimethylation of H3K27 and altering the expression of over half of the genes. The severity of the disease is linked to continued down regulation of genes.

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

editv4:Genes and Main Pathways Involved

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The most important genes involved in the development and progress of ATLL are the Tax and HBZ contributed by the HTLV-1 virus and genes listed in gene mutations table (above) from the host. The main pathways involved are TCR-NF-κB signaling by gain of function and amplifications in PLCG1, VAV1 and FYN, CD28, PRKCB, CARD11, IRF4 and RHOA; and loss of function mutations or deletions in CBLB, TRAF, TNFAIP3 and CSNK1A1.

Genes involving the immune surveillance program are also heavy altered to evade the immune response either by deletions in MHC class1 molecules, CD58, FAS or constitutive activation of PD-L1.

Genes involved in the Lymphocyte activation and differentiation(IRF4, GATA3, IKZF2) are also altered.

Chemokine receptors including CCR4 and CCR7 are responsible for the infiltration of neoplastic cells into other organs along with activation of PI3K/AKT signaling.

The epigenetic mechanism is also exploited to alter gene expression and promote ATLL progression as explained above.

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Genetic Diagnostic Testing Methods

Initial diagnosis of ATLL should include a comprehensive physical exam with skin evaluation and CT scans of the chest, abdomen and pelvis. The laboratory evaluation should include: a complete blood count (CBC), metabolic panel (serum electrolyte levels, calcium, creatinine and blood urea nitrogen) and serum LDH levels. Testing methods including PCR, Flow Cytometry, ELISA, serology, and immunohistochemistry in addition to morphologic studies may be employed to diagnose ATLL.

Familial Forms

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Additional Information

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Links

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References

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Notes

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Prior Author(s):

*Citation of this Page: “Adult T-cell leukaemia/lymphoma”. Compendium of Cancer Genome Aberrations (CCGA), Cancer Genomics Consortium (CGC), updated 02/10/2025, https://ccga.io/index.php/HAEM5:Adult_T-cell_leukaemia/lymphoma.