HAEM5:Primary cutaneous gamma/delta T-cell lymphoma: Difference between revisions

[unchecked revision]

[checked revision]

← Older edit

VisualWikitext

Latest revision as of 22:48, 6 January 2026

Haematolymphoid Tumours (WHO Classification, 5th ed.)

Primary Author(s)*

Mahzad Azimpouran, MD; Sumire Kitahara, MD; Cedars-Sinai, Los Angeles, CA

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	Primary cutaneous T-cell lymphoid proliferations and lymphomas
Subtype(s)	Primary cutaneous gamma/delta T-cell lymphoma

Related Terminology

Acceptable	N/A
Not Recommended	N/A

Gene Rearrangements

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
Arm‑level chromosomal alterations (e.g., 9p, 18q deletions; 1q, 7q,15q gains)	—	Copy number loss or gain → altered gene dosage of tumour suppressors/oncogenes	Other / chromosomal alteration	Recurrent (5‑20%) (9p del ~22%, 18q del ~22%; 1q/7q/15q gains ~33‑39%)	D / P	No	These structural changes suggest genomic instability and aggressive biology; may help risk stratification though not diagnostic per se^[1]
Fusion: FYN :: (probable partner TRAF3IP2)	TRAF3IP2	Structural alteration – deletion/exon8 deletion → (in other T‑cell lymphomas) FYN::TRAF3IP2 fusion leading to SRC‑family kinase activation; in this PCGDTCL case FYN exon8 deletion noted	Oncogene / Other	Rare (<5%) (single case reported)	T	No	Very recently described; may represent novel driver/target; further cases needed^[2]
Fusion: PCM1 :: JAK2	PCM1	Fusion → juxtaposition of dimerization domain of PCM1 with kinase domain of JAK2 → constitutive JAK2 activation	Oncogene	Rare (<5%) (single documented PCGDTCL case)	T	No	Known in other T‑cell and myeloid neoplasms; in PCGDTCL this double‐hit case had PCM1::JAK2 + TBL1XR1::TP63 fusion; patient refractory to JAK inhibitor^[3]
Fusion: TBL1XR1 :: TP63	TBL1XR1	Fusion → truncation/overexpression of ΔNp63 form → oncogenic p63 signalling	Oncogene / Other	Rare (<5%) (same single case) (	P / T	No	Associated with aggressive behaviour in T‑cell lymphomas; in the reported PCGDTCL case contributed to aggressive course and JAK inhibitor resistance^[3]

Individual Region Genomic Gain/Loss/LOH

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
1p	Loss	1p36.11	ARID1A	P	No	Deleted in ~28% of cases. Indicates epigenetic/chromatin modifier pathway involvement^[1]
1q	Gain (arm‐level amplification)	1q (approx chr1:144,000,000‑249,000,000)	Multiple genes on 1q (unspecified)	P / T	No	Amplification in ~33% of cases. Potential gene dosage effect; specific driver gene not yet defined^[1]
2q	Loss	2q37.3	PDCD1	P	No	Deletion in ~22% of cases. Immune checkpoint gene loss; potential therapeutic‑escape mechanism^[1]
7q	Gain (arm‐level)	7q (approx chr7:100,000,000‑159,000,000)	Multiple genes on 7q (unspecified)	P	No	Amplification in ~39% of cases. Suggests MAPK/other pathway involvement but specific gene not yet defined.
9p	Loss (deletion)	9p21.3 (~ chr9:21,900,000‑22,200,000)	CDKN2A, CDKN2B	P	No	High‐frequency homozygous or biallelic deletion (~61% of cases; 45% biallelic) in PCGDTCL. (PMC) Suggests aggressive biology, prognostic marker candidate^[1]
10q	Loss	10q24.1	FAS	P	No	Deletion in ~22% of cases. Loss of apoptosis regulator; may contribute to immune‑escape^[1]
15q	Gain (arm‐level)	15q (approx chr15:30,000,000‑102,000,000)	Multiple genes on 15q (unspecified)	P	No	Amplification in ~33% of cases. Likely reflects tumour evolution rather than diagnostic biomarker^[1]
18q	Loss	18q (arm level; no precise minimal region specified)	Putative tumour suppressors (unspecified)	P	No	Recurrent deletion ~22% in PCGDTCL cohort. May reflect genomic instability and poor outcome^[1]

Characteristic Chromosomal or Other Global Mutational Patterns

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
Arm‑level somatic copy‑number variation (SCNV) (average ~4 arm‑level events per case; median ~166.5 SCNVs per sample)^[1]	Reflects genomic instability; multiple gains and losses of whole chromosome arms likely contribute to oncogenesis and progression by altering gene dosage of multiple oncogenes/tumour suppressors simultaneously. (PMC)	Common (>20%) — nearly all cases show multiple arm‑level events (median 4 per sample) (PMC)	P	No	High genomic complexity may explain aggressive behaviour and poor response to therapy. Could impact prognosis or treatment resistance but not yet in guidelines.
High burden of somatic copy‑number variants (SCNVs) relative to single‐nucleotide variants (SNVs) (e.g., median ~166.5 SCNVs per sample) ^[1]	Suggests that structural genomic alterations dominate the mutational landscape, perhaps more so than classical hotspot SNVs, indicating a biology driven by large‑scale genomic disruption rather than just point mutations.	Common (>20%)	P	No	Recognising this pattern may guide expectation of complexity, but this is not currently used clinically for diagnosis or treatment.
Distinct cell‑of‑origin signature: Vδ1 vs Vδ2 subtype (epidermal/dermal Vδ1 vs panniculitic Vδ2) ^[1]	Different tissue compartments (epidermis/dermis vs subcutaneous) correspond to distinct γδ T‑cell subsets (Vδ1 vs Vδ2). The cell‑of‑origin influences mutational signatures (eg UV signature in Vδ1) and clinical phenotype (Vδ2 more aggressive)^[1]	Recurrent (5‑20%) — this pattern applies in a subset of cases defined by tissue involvement and TCR subtype.	D / P	No	This dichotomy may help stratify patients clinically (Vδ2 subtype worse prognosis) but is not currently part of formal diagnostic or therapeutic guidelines.
Ultraviolet (UV) mutational signature in Vδ1 subtype ^[1]	The epidermal/dermal Vδ1 γδ T‑cell lymphomas exhibit a UV signature in their mutation spectrum, likely reflecting skin localization and UV exposure contributing to oncogenesis.	Recurrent (5‑20%) — seen in Vδ1 cases but not all.	P	No	Could suggest etiology and may influence prognosis; though not yet used for therapy selection.
Frequent deletions of 9p21.3 (CDKN2A region) (part of the SCNV pattern) ^[1]	Loss of CDKN2A/p14^ARF leads to cell‑cycle deregulation, loss of tumour suppressor control: a hallmark of many aggressive lymphomas	Common (>20%) (approx 61% of cases)	P	No	Among the most prevalent genomic events in PCGDTCL — potential prognostic marker though not yet guideline‑endorsed.
Multiple gains of oncogenic arms (e.g., 1q, 7q, 15q) and corresponding losses (eg 18q) ^[1]	Gains may increase dosage of oncogenes; losses may reduce tumour suppressor dosage—together contributing to malignant phenotype	Recurrent (5‑20%) for specific arm‑level changes (e.g., 1q gain ~33%, 7q ~39%, 15q ~33%)	P	No	These arm‑level events indicate complexity; may correlate with poorer prognosis; not yet actionable in therapy.
TCR chain repertoire restriction / non‑random Vγ or Vδ usage (eg Vγ3Vδ2 in panniculitic cases) ^[1]	Suggests antigen‑driven or tissue‐resident γδ T‑cell proliferation; highlights non‑random selection of malignant clones	Recurrent (5‑20%) in defined subtypes	D	No	Might help refine subclassification of PCGDTCL; not currently used in routine diagnostic algorithms.

Gene Mutations (SNV/INDEL)

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
STAT5B	Activating missense (e.g., p.N642H) → constitutive downstream STAT5 signalling	Oncogene	Recurrent (~5‑20 %) — e.g., in the 2020 genomic study: JAK/STAT mutations ~21 % of cases^[1]	T / P: Therapeutic potential (JAK/STAT inhibition); Prognostic implication (pathway addiction/resistance)	No	Mutant STAT5B (especially N642H) shown to induce T‑cell neoplasia in models; in PCGDTCL JAK/STAT addiction shown clinically ^[4]^[5]
STAT3	Activating missense (SH2 domain) → constitutive STAT3 signalling	Oncogene	Rare (<5 %) to Recurrent (≈5‑10 %) (in NK/γδ‑T lymphomas earlier)	T / P	No	Less frequent than STAT5B in PCGDTCL; part of JAK/STAT pathway involvement^[1]^[4]
JAK3	Activating mutation (e.g., p.R657W) → JAK3 tyrosine kinase activation	Oncogene	Rare (<5 %) (noted in the Daniels et al. cohort)	T	No	Supports JAK/STAT involvement; one case report showed response to JAK inhibition^[5]
KRAS	Activating hotspot mutations (e.g., G12D, Q61H, D119N) → RAS/MAPK activation	Oncogene	Recurrent (~5‑20 %) — “KRAS was the most frequently mutated oncogene” ^[1]	T / P	No	MAPK pathway appears relevant; patients with MAPK‑pathway driver mutations had worse survival in the cohort^[1]
NRAS	Activating hotspot mutation → RAS/MAPK activation	Oncogene	Rare (<5 %) to Recurrent (~5‑10 %)	T / P	No	Part of the same RAS/MAPK pathway as KRAS; less common.
MAPK1	Activating mutation → MAPK1 signalling activation	Oncogene	Rare (<5 %)	T	No	Also in MAPK pathway; limited data in PCGDTCL^[1]^[4]
MYC	Activating missense mutation (e.g., p.P74L) → MYC pathway up‑regulation	Oncogene	Rare (<5 %)	P / T	No	MYC pathway involvement may contribute to the aggressive phenotype; direct targeting not yet established^[1]
MYCN	Activating mutation (e.g., p.G34R) → MYCN pathway activation	Oncogene	Rare (<5 %)	P / T	No	Highlights involvement of MYC‑family beyond MYC itself in this disease^[1]

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.

Epigenomic Alterations

N/A

Genes and Main Pathways Involved

Gene; Genetic Alteration	Pathway	Pathophysiologic Outcome
DNMT3A (DNA methyltransferase)	Loss‑of‑function mutations or deletions → reduced de novo DNA methylation; “epigenetic writer” defect (DNA methylation pathway)^[6]	Deregulation of gene silencing; tumour suppressor genes may remain unmethylated or aberrantly methylated → genomic instability, aberrant T‑cell differentiation/activation
TET2 (methylcytosine dioxygenase)	Loss‑of‑function mutations → failure of DNA 5‑mC → 5‑hmC demethylation (“epigenetic eraser” defect)^[6]	Aberrant hypermethylation or demethylation patterns; influences T‑cell development and malignant transformation (e.g., in T‑fh lymphomas)
IDH2 (metabolic enzyme altering epigenome)	Gain‑of‑function mutation (e.g., R172) → produces 2‑hydroxyglutarate → inhibits TET family → epigenetic dysregulation^[6]	Oncometabolite‑driven methylation changes, impaired differentiation, proliferation of malignant T cells
ARID1A (SWI/SNF chromatin‑remodeller)	Loss‑of‑function mutation/deletion → impaired nucleosome remodelling, altered chromatin accessibility (“chromatin remodeller”)^[6]	Reduced tumour‑suppressor gene expression due to chromatin compaction; may influence immune microenvironment and genomic instability
KMT2D / KMT2A (H3K4 methyltransferases)	Loss‑of‑function mutations (“histone‑writer” defect) → decreased H3K4 methylation (activating mark)^[7]	Impaired activation of gene expression programs (differentiation, apoptosis) → contributes to malignant transformation
KDM6A (H3K27 demethylase)	Loss‑of‑function → accumulation of H3K27me3 (repressive histone mark) (“histone‑eraser” defect)^[7]	Further chromatin repression of tumour‑suppressor genes; may enhance survival of malignant T cells
EZH2 (PRC2 complex methyltransferase)	Overexpression/gain of function → increased H3K27me3 (“histone‑writer” overactivity) ^[6]	Enhanced silencing of differentiation/apoptosis genes; contributes to aggressive lymphoma phenotypes
CREBBP / EP300 (histone acetyl‑transferases)	Loss‑of‑function mutations (“histone‑writer” defect) → reduced histone acetylation and gene activation^[7]	Diminished transcriptional activation of tumour‑suppressor/immune genes; may drive malignant progression
DNA methylation of specific tumour‑suppressor loci (e.g., CDKN2A promoter; FAS promoter)	Hypermethylation of promoter CpG islands → silencing of tumor suppressor / apoptosis‑initiator genes^[8]	Loss of cell‑cycle control or apoptosis leads to malignant T‑cell survival/proliferation

Genetic Diagnostic Testing Methods

Method	Description	Type of Alteration Detected	Advantages	Limitations	Clinical Use in PCGDTCL
Next-Generation Sequencing (NGS)	High-throughput sequencing of targeted gene panels, whole-exome, or whole-genome sequencing	SNVs, INDELs, copy number variants (CNVs), some fusions (if RNA-seq included)	Comprehensive mutation detection; scalable; can detect multiple variants simultaneously	Requires high-quality DNA/RNA; bioinformatics expertise needed; cost-intensive	Main tool for mutational profiling in PCGDTCL; used in research and increasingly in clinical labs
Targeted Gene Panels (amplicon or hybrid capture-based)	Sequencing of a defined set of genes known to be relevant	SNVs, INDELs, limited CNVs, hotspot fusions (if included)	Faster, cheaper than WES/WGS; focused on clinically relevant genes	May miss novel or unexpected mutations; limited to panel content	Often used clinically to screen for mutations in JAK/STAT, RAS pathways in PCGDTCL
Fluorescence In Situ Hybridization (FISH)	DNA probes hybridize to metaphase or interphase chromosomes	Structural chromosomal alterations, gene fusions, amplifications, deletions	Visualizes gene rearrangements and copy number changes; established clinical use	Limited to known targets; low resolution; labor-intensive	Used to detect known translocations or gene amplifications (e.g., MYC) in lymphoma diagnosis
Array Comparative Genomic Hybridization (aCGH) / SNP Arrays	Genome-wide detection of copy number alterations and LOH	Copy number gains, losses, LOH (Loss of heterozygosity)	Genome-wide coverage; detects submicroscopic CNVs	Cannot detect balanced translocations or point mutations; resolution depends on array density	Useful for detecting large chromosomal alterations in lymphoma samples
RNA Sequencing (RNA-Seq)	Sequencing of transcriptome	Gene fusions, splice variants, expression levels	Detects novel and known fusions; measures gene expression; alternative splicing	RNA quality sensitive; bioinformatics expertise needed	Research use for identifying novel fusion partners or expression signatures in PCGDTCL
Sanger Sequencing	Chain termination sequencing of PCR-amplified regions	SNVs and small indels	Gold standard for validation; high accuracy	Low throughput; not suitable for large panels	Used to confirm NGS-identified mutations
Digital Droplet PCR (ddPCR) / qPCR	Highly sensitive quantification of known mutations or gene rearrangements	Known point mutations, copy number changes	Very sensitive, quantitative; fast turnaround	Limited to known mutations; not comprehensive	Useful for monitoring known mutations (e.g., STAT5B N642H) in minimal residual disease (MRD) or treatment response
Immunohistochemistry (IHC) (surrogate genetic marker)	Antibody staining of protein expression	Protein expression reflecting genetic alterations (e.g., pSTAT5B, MYC)	Widely available; easy to implement	Indirect; may not perfectly correlate with mutation status	Supportive role in diagnosis and prognosis, not definitive genetic test

Familial Forms

There are currently no well-established familial or hereditary forms described in the literature.

Additional Information

N/A

Links

N/A

References

↑ ^1.00 ^1.01 ^1.02 ^1.03 ^1.04 ^1.05 ^1.06 ^1.07 ^1.08 ^1.09 ^1.10 ^1.11 ^1.12 ^1.13 ^1.14 ^1.15 ^1.16 ^1.17 ^1.18 ^1.19 ^1.20 ^1.21 ^1.22 Daniels, Jay; et al. (2020-04-14). "Cellular origins and genetic landscape of cutaneous gamma delta T cell lymphomas". Nature Communications. 11 (1): 1806. doi:10.1038/s41467-020-15572-7. ISSN 2041-1723. PMC 7156460 Check |pmc= value (help). PMID 32286303 Check |pmid= value (help).
↑ Azimpouran, Mahzad; et al. (2024-12-01). "Rapidly Progressive Primary Cutaneous Gamma Delta T-Cell Lymphoma With FYN Gene Alteration". The American Journal of Dermatopathology. 46 (12): e120–e123. doi:10.1097/DAD.0000000000002856. ISSN 1533-0311. PMID 39412302 Check |pmid= value (help).
↑ ^3.0 ^3.1 Fadl, Amr; et al. (2023-09). "Primary cutaneous gamma/delta T-cell lymphoma with simultaneous JAK2 and TP63 rearrangements: a new double-hit?". Histopathology. 83 (3): 492–495. doi:10.1111/his.14973. ISSN 1365-2559. PMC 10524708 Check |pmc= value (help). PMID 37308177 Check |pmid= value (help). Check date values in: |date= (help)
↑ ^4.0 ^4.1 ^4.2 Küçük, Can; et al. (2015-01-14). "Activating mutations of STAT5B and STAT3 in lymphomas derived from γδ-T or NK cells". Nature Communications. 6: 6025. doi:10.1038/ncomms7025. ISSN 2041-1723. PMC 7743911 Check |pmc= value (help). PMID 25586472.
↑ ^5.0 ^5.1 Zhang, Yue; et al. (2025-04-15). "Addiction of primary cutaneous γδ T cell lymphomas to JAK/STAT signaling". The Journal of Clinical Investigation. 135 (8): e180417. doi:10.1172/JCI180417. ISSN 1558-8238. PMC 11996904 Check |pmc= value (help). PMID 40231467 Check |pmid= value (help).
↑ ^6.0 ^6.1 ^6.2 ^6.3 ^6.4 Zhang, Ping; et al. (2020-11-07). "Epigenetic alterations and advancement of treatment in peripheral T-cell lymphoma". Clinical Epigenetics. 12 (1): 169. doi:10.1186/s13148-020-00962-x. ISSN 1868-7083. PMC 7648940 Check |pmc= value (help). PMID 33160401 Check |pmid= value (help).
↑ ^7.0 ^7.1 ^7.2 Ahmed, Nada; et al. (2020-02). "Targeting epigenetic regulators in the treatment of T-cell lymphoma". Expert Review of Hematology. 13 (2): 127–139. doi:10.1080/17474086.2020.1711732. ISSN 1747-4094. PMC 7110907 Check |pmc= value (help). PMID 31903826. Check date values in: |date= (help)
↑ Hara, Natsumi; et al. (2022-03-24). "Epigenetics of Cutaneous T-Cell Lymphomas". International Journal of Molecular Sciences. 23 (7): 3538. doi:10.3390/ijms23073538. ISSN 1422-0067. PMC 8998216 Check |pmc= value (help). PMID 35408897 Check |pmid= value (help).

Notes

*Citation of this Page: Azimpouran M, Kitahara S. “Primary cutaneous gamma/delta T-cell lymphoma”. Compendium of Cancer Genome Aberrations (CCGA), Cancer Genomics Consortium (CGC), updated 01/6/2026, https://ccga.io/index.php/HAEM5:Primary_cutaneous_gamma/delta_T-cell_lymphoma.

*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 Associate Editor or other CCGA representative. When pages have a major update, the new author will be acknowledged at the beginning of the page, and those who contributed previously will be acknowledged below as a prior author.

Prior Author(s): N/A

[:0-1] 1.00 ^1.01 ^1.02 ^1.03 ^1.04 ^1.05 ^1.06 ^1.07 ^1.08 ^1.09 ^1.10 ^1.11 ^1.12 ^1.13 ^1.14 ^1.15 ^1.16 ^1.17 ^1.18 ^1.19 ^1.20 ^1.21 ^1.22 Daniels, Jay; et al. (2020-04-14). "Cellular origins and genetic landscape of cutaneous gamma delta T cell lymphomas". Nature Communications. 11 (1): 1806. doi:10.1038/s41467-020-15572-7. ISSN 2041-1723. PMC 7156460 Check |pmc= value (help). PMID 32286303 Check |pmid= value (help).

[2] Azimpouran, Mahzad; et al. (2024-12-01). "Rapidly Progressive Primary Cutaneous Gamma Delta T-Cell Lymphoma With FYN Gene Alteration". The American Journal of Dermatopathology. 46 (12): e120–e123. doi:10.1097/DAD.0000000000002856. ISSN 1533-0311. PMID 39412302 Check |pmid= value (help).

[:2-3] 3.0 ^3.1 Fadl, Amr; et al. (2023-09). "Primary cutaneous gamma/delta T-cell lymphoma with simultaneous JAK2 and TP63 rearrangements: a new double-hit?". Histopathology. 83 (3): 492–495. doi:10.1111/his.14973. ISSN 1365-2559. PMC 10524708 Check |pmc= value (help). PMID 37308177 Check |pmid= value (help). Check date values in: |date= (help)

[:1-4] 4.0 ^4.1 ^4.2 Küçük, Can; et al. (2015-01-14). "Activating mutations of STAT5B and STAT3 in lymphomas derived from γδ-T or NK cells". Nature Communications. 6: 6025. doi:10.1038/ncomms7025. ISSN 2041-1723. PMC 7743911 Check |pmc= value (help). PMID 25586472.

[:3-5] 5.0 ^5.1 Zhang, Yue; et al. (2025-04-15). "Addiction of primary cutaneous γδ T cell lymphomas to JAK/STAT signaling". The Journal of Clinical Investigation. 135 (8): e180417. doi:10.1172/JCI180417. ISSN 1558-8238. PMC 11996904 Check |pmc= value (help). PMID 40231467 Check |pmid= value (help).

[:4-6] 6.0 ^6.1 ^6.2 ^6.3 ^6.4 Zhang, Ping; et al. (2020-11-07). "Epigenetic alterations and advancement of treatment in peripheral T-cell lymphoma". Clinical Epigenetics. 12 (1): 169. doi:10.1186/s13148-020-00962-x. ISSN 1868-7083. PMC 7648940 Check |pmc= value (help). PMID 33160401 Check |pmid= value (help).

[:5-7] 7.0 ^7.1 ^7.2 Ahmed, Nada; et al. (2020-02). "Targeting epigenetic regulators in the treatment of T-cell lymphoma". Expert Review of Hematology. 13 (2): 127–139. doi:10.1080/17474086.2020.1711732. ISSN 1747-4094. PMC 7110907 Check |pmc= value (help). PMID 31903826. Check date values in: |date= (help)

[8] Hara, Natsumi; et al. (2022-03-24). "Epigenetics of Cutaneous T-Cell Lymphomas". International Journal of Molecular Sciences. 23 (7): 3538. doi:10.3390/ijms23073538. ISSN 1422-0067. PMC 8998216 Check |pmc= value (help). PMID 35408897 Check |pmid= value (help).

[1]

[2]

[3]

[4]

[5]

[6]

[7]

[8]

HAEM5:Primary cutaneous gamma/delta T-cell lymphoma: Difference between revisions

Latest revision as of 22:48, 6 January 2026

Contents

Primary Author(s)*

WHO Classification of Disease

Related Terminology

Gene Rearrangements

Individual Region Genomic Gain/Loss/LOH

Characteristic Chromosomal or Other Global Mutational Patterns

Gene Mutations (SNV/INDEL)

Epigenomic Alterations

Genes and Main Pathways Involved

Genetic Diagnostic Testing Methods

Familial Forms

Additional Information

Links

References

Notes

Navigation menu

@@ Line 1: / Line 1: @@
-{{DISPLAYTITLE:Primary cutaneous gamma/delta T-cell lymphoma}}
+[[HAEM5:Table_of_Contents|Haematolymphoid Tumours (WHO Classification, 5th ed.)]]
-[[HAEM5:Table_of_Contents|Haematolymphoid Tumours (5th ed.)]]
-{{Under Construction}}
-<span style="color:#0070C0">(General Instructions – The main focus of these pages is the clinically significant genetic alterations in each disease type. Use [https://www.genenames.org/ <u>HUGO-approved gene names and symbols</u>] (italicized when appropriate), [https://varnomen.hgvs.org/ 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). 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 </span><u>[[Author_Instructions]]</u><span style="color:#0070C0"> and [[Frequently Asked Questions (FAQs)|<u>FAQs</u>]] as well as contact your [[Leadership|<u>Associate Editor</u>]] or [mailto:CCGA@cancergenomics.org <u>Technical Support</u>])</span>
 ==Primary Author(s)*==
-Put your text here<span style="color:#0070C0"> (''Name and affiliation; example:'' Jane Smith, PhD, Institute of Genomics) </span>
+Mahzad Azimpouran, MD; Sumire Kitahara, MD; Cedars-Sinai, Los Angeles, CA
+==WHO Classification of Disease==
-__TOC__
+{| class="wikitable"
+!Structure
-==Cancer Category / Type==
+!Disease
+|-
-Put your text here
+|Book
+|Haematolymphoid Tumours (5th ed.)
+|-
+|Category
+|T-cell and NK-cell lymphoid proliferations and lymphomas
+|-
+|Family
+|Mature T-cell and NK-cell neoplasms
+|-
+|Type
+|Primary cutaneous T-cell lymphoid proliferations and lymphomas
+|-
+|Subtype(s)
+|Primary cutaneous gamma/delta T-cell lymphoma
+|}
-==Cancer Sub-Classification / Subtype==
+==Related Terminology==
-Put your text here
-==Definition / Description of Disease==
-Put your text here <span style="color:#0070C0">(''Instructions: Brief description of approximately one paragraph - include disease context relative to other WHO classification categories referring to the specific WHO book pages, diagnostic criteria if applicable, and differential diagnosis if applicable'') </span>
-==Synonyms / Terminology==
-Put your text here <span style="color:#0070C0">(''Instructions: Include currently used terms and major historical ones, adding “(historical)” after the latter.'') </span>
-==Epidemiology / Prevalence==
-Put your text here
-==Clinical Features==
-Put your text here and fill in the table <span style="color:#0070C0">(''Instruction: Can include references in the table'') </span>
 {| class="wikitable"
-|'''Signs and Symptoms'''
+|Acceptable
-|EXAMPLE Asymptomatic (incidental finding on complete blood counts)
+|N/A
-EXAMPLE B-symptoms (weight loss, fever, night sweats)
-EXAMPLE Fatigue
-EXAMPLE Lymphadenopathy (uncommon)
 |-
-|'''Laboratory Findings'''
+|Not Recommended
-|EXAMPLE Cytopenias
+|N/A
-EXAMPLE Lymphocytosis (low level)
 |}
-==Sites of Involvement==
+==Gene Rearrangements==
-Put your text here <span style="color:#0070C0">(''Instruction: Indicate physical sites; Example: nodal, extranodal, bone marrow'') </span>
-==Morphologic Features==
-Put your text here
-==Immunophenotype==
-Put your text here and fill in the table <span style="color:#0070C0">(''Instruction: Can include references in the table'') </span>
 {| class="wikitable sortable"
 |-
-!Finding!!Marker
+!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
 |-
-|Positive (universal)||EXAMPLE CD1
+|'''Arm‑level chromosomal alterations (e.g., 9p,  18q deletions; 1q, 7q,15q gains)'''
+|—
+|Copy number loss or gain → altered gene dosage of tumour  suppressors/oncogenes
+|Other / chromosomal alteration
+|Recurrent (5‑20%) (9p del ~22%, 18q del ~22%; 1q/7q/15q  gains ~33‑39%)
+|D / P
+|No
+|These structural changes suggest genomic instability and  aggressive biology; may help risk stratification though not diagnostic per se<ref name=":0">{{Cite journal|last=Daniels|first=Jay|last2=Doukas|first2=Peter G.|last3=Escala|first3=Maria E. Martinez|last4=Ringbloom|first4=Kimberly G.|last5=Shih|first5=David J. H.|last6=Yang|first6=Jingyi|last7=Tegtmeyer|first7=Kyle|last8=Park|first8=Joonhee|last9=Thomas|first9=Jane J.|date=2020-04-14|title=Cellular origins and genetic landscape of cutaneous gamma delta T cell lymphomas|url=https://pubmed.ncbi.nlm.nih.gov/32286303|journal=Nature Communications|volume=11|issue=1|pages=1806|doi=10.1038/s41467-020-15572-7|issn=2041-1723|pmc=7156460|pmid=32286303}}</ref>
 |-
-|Positive (subset)||EXAMPLE CD2
+|'''Fusion: FYN :: (probable partner TRAF3IP2)'''
+|TRAF3IP2
+|Structural alteration – deletion/exon8 deletion → (in  other T‑cell lymphomas) FYN::TRAF3IP2 fusion leading to SRC‑family kinase  activation; in this PCGDTCL case FYN exon8 deletion noted
+|Oncogene / Other
+|Rare (<5%) (single case reported)
+|T
+|No
+|Very recently described; may represent novel  driver/target; further cases needed<ref>{{Cite journal|last=Azimpouran|first=Mahzad|last2=Bui|first2=Chau M.|last3=Balzer|first3=Bonnie|last4=Kitahara|first4=Sumire|date=2024-12-01|title=Rapidly Progressive Primary Cutaneous Gamma Delta T-Cell Lymphoma With FYN Gene Alteration|url=https://pubmed.ncbi.nlm.nih.gov/39412302|journal=The American Journal of Dermatopathology|volume=46|issue=12|pages=e120–e123|doi=10.1097/DAD.0000000000002856|issn=1533-0311|pmid=39412302}}</ref>
 |-
-|Negative (universal)||EXAMPLE CD3
+|'''Fusion: PCM1 :: JAK2'''
+|PCM1
+|Fusion → juxtaposition of dimerization domain of PCM1  with kinase domain of JAK2 → constitutive JAK2 activation
+|Oncogene
+|Rare (<5%) (single documented PCGDTCL case)
+|T
+|No
+|Known in other T‑cell and myeloid neoplasms; in PCGDTCL  this double‐hit  case had PCM1::JAK2 + TBL1XR1::TP63 fusion; patient refractory to JAK  inhibitor<ref name=":2">{{Cite journal|last=Fadl|first=Amr|last2=Bennani|first2=N. Nora|last3=Comfere|first3=Nneka|last4=Durani|first4=Urshila|last5=Greipp|first5=Patricia T.|last6=Feldman|first6=Andrew L.|date=2023-09|title=Primary cutaneous gamma/delta T-cell lymphoma with simultaneous JAK2 and TP63 rearrangements: a new double-hit?|url=https://pubmed.ncbi.nlm.nih.gov/37308177|journal=Histopathology|volume=83|issue=3|pages=492–495|doi=10.1111/his.14973|issn=1365-2559|pmc=10524708|pmid=37308177}}</ref>
 |-
-|Negative (subset)||EXAMPLE CD4
+|'''Fusion: TBL1XR1 :: TP63'''
+|TBL1XR1
+|Fusion → truncation/overexpression of ΔNp63 form →  oncogenic p63 signalling
+|Oncogene / Other
+|Rare (<5%) (same single case) (
+|P / T
+|No
+|Associated with aggressive behaviour in T‑cell lymphomas;  in the reported PCGDTCL case contributed to aggressive course and JAK  inhibitor resistance<ref name=":2" />
 |}
+==Individual Region Genomic Gain/Loss/LOH==
-==Chromosomal Rearrangements (Gene Fusions)==
-Put your text here and fill in the table
 {| class="wikitable sortable"
 |-
-!Chromosomal Rearrangement!!Genes in Fusion (5’ or 3’ Segments)!!Pathogenic Derivative!!Prevalence
+!Chr #!!Gain, Loss, Amp, LOH!!Minimal Region Cytoband and/or Genomic Coordinates [Genome Build; Size]!!Relevant Gene(s)
-!Diagnostic Significance (Yes, No or Unknown)
+!Diagnostic, Prognostic, and Therapeutic Significance - D, P, T
-!Prognostic Significance (Yes, No or Unknown)
+!Established Clinical Significance Per Guidelines - Yes or No (Source)
-!Therapeutic Significance (Yes, No or Unknown)
+!Clinical Relevance Details/Other Notes
-!Notes
+|-
+|1p
+|Loss
+|1p36.11
+|ARID1A
+|P
+|No
+|Deleted in ~28% of cases. Indicates epigenetic/chromatin modifier pathway involvement<ref name=":0" />
+|-
+|1q
+|Gain (arm‐level  amplification)
+|1q (approx chr1:144,000,000‑249,000,000)
+|Multiple genes on 1q (unspecified)
+|P / T
+|No
+|Amplification in ~33% of cases. Potential gene dosage effect; specific driver gene not yet defined<ref name=":0" />
 |-
-|EXAMPLE t(9;22)(q34;q11.2)||EXAMPLE 3'ABL1 / 5'BCR||EXAMPLE der(22)||EXAMPLE 20% (COSMIC)
+|2q
-EXAMPLE 30% (add reference)
+|Loss
-|Yes
+|2q37.3
+|PDCD1
+|P
 |No
-|Yes
+|Deletion in ~22% of cases. Immune checkpoint gene loss; potential therapeutic‑escape mechanism<ref name=":0" />
-|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).
-|}
-==Individual Region Genomic Gain / Loss / LOH==
-Put your text here and fill in the table <span style="color:#0070C0">(''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.'') </span>
-{| class="wikitable sortable"
 |-
-!Chr #!!Gain / Loss / Amp / LOH!!Minimal Region Genomic Coordinates [Genome Build]!!Minimal Region Cytoband
+|7q
-!Diagnostic Significance (Yes, No or Unknown)
+|Gain (arm‐level)
-!Prognostic Significance (Yes, No or Unknown)
+|7q (approx chr7:100,000,000‑159,000,000)
-!Therapeutic Significance (Yes, No or Unknown)
+|Multiple genes on 7q (unspecified)
-!Notes
+|P
+|No
+|Amplification in ~39% of cases. Suggests MAPK/other pathway involvement but specific gene not yet defined.
 |-
-|EXAMPLE
+|9p
+|Loss (deletion)
+|9p21.3 (~ chr9:21,900,000‑22,200,000)
-|EXAMPLE Loss
+|CDKN2A, CDKN2B
-|EXAMPLE
+|P
-chr7:1- 159,335,973 [hg38]
-|EXAMPLE
-chr7
-|Yes
-|Yes
 |No
-|EXAMPLE
+|High‐frequency  homozygous or biallelic deletion (~61% of cases; 45% biallelic) in PCGDTCL. (PMC)  Suggests aggressive biology, prognostic marker candidate<ref name=":0" />
-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
+|10q
+|Loss
+|10q24.1
-|EXAMPLE Gain
+|FAS
-|EXAMPLE
+|P
-chr8:1-145,138,636 [hg38]
-|EXAMPLE
-chr8
 |No
+|Deletion in ~22% of cases. Loss of apoptosis regulator; may contribute to immune‑escape<ref name=":0" />
+|-
+|15q
+|Gain (arm‐level)
+|15q (approx chr15:30,000,000‑102,000,000)
+|Multiple genes on 15q (unspecified)
+|P
 |No
+|Amplification in ~33% of cases.  Likely reflects tumour evolution rather than diagnostic biomarker<ref name=":0" />
+|-
+|18q
+|Loss
+|18q (arm level; no precise minimal region specified)
+|Putative tumour suppressors (unspecified)
+|P
 |No
-|EXAMPLE
+|Recurrent deletion ~22% in PCGDTCL cohort. May reflect genomic instability and poor outcome<ref name=":0" />
-Common recurrent secondary finding for t(8;21) (add reference).
 |}
-==Characteristic Chromosomal Patterns==
+==Characteristic Chromosomal or Other Global Mutational Patterns==
-Put your text here <span style="color:#0070C0">(''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'')</span>
 {| class="wikitable sortable"
 |-
 !Chromosomal Pattern
-!Diagnostic Significance (Yes, No or Unknown)
+!Molecular Pathogenesis
-!Prognostic Significance (Yes, No or Unknown)
+!Prevalence -
-!Therapeutic Significance (Yes, No or Unknown)
+Common >20%, Recurrent 5-20% or Rare <5% (Disease)
-!Notes
+!Diagnostic, Prognostic, and Therapeutic Significance - D, P, T
+!Established Clinical Significance Per Guidelines - Yes or No (Source)
+!Clinical Relevance Details/Other Notes
+|-
+|'''Arm‑level somatic copy‑number variation  (SCNV)''' (average ~4 arm‑level events per case; median ~166.5  SCNVs per sample)<ref name=":0" />
+|Reflects genomic instability; multiple gains and losses  of whole chromosome arms likely contribute to oncogenesis and progression by  altering gene dosage of multiple oncogenes/tumour suppressors simultaneously.  (PMC)
+|'''Common''' (>20%) — nearly all  cases show multiple arm‑level events (median 4 per sample) (PMC)
+|P
+|No
+|High genomic complexity may explain aggressive behaviour  and poor response to therapy. Could impact prognosis or treatment resistance  but not yet in guidelines.
+|-
+|'''High burden of somatic copy‑number variants  (SCNVs) relative to single‐nucleotide  variants (SNVs)''' (e.g., median ~166.5 SCNVs per sample) <ref name=":0" />
+|Suggests that structural genomic alterations dominate the  mutational landscape, perhaps more so than classical hotspot SNVs, indicating  a biology driven by large‑scale genomic disruption rather than just point  mutations.
+|'''Common''' (>20%)
+|P
+|No
+|Recognising this pattern may guide expectation of  complexity, but this is not currently used clinically for diagnosis or  treatment.
+|-
+|'''Distinct cell‑of‑origin signature: Vδ1 vs Vδ2  subtype''' (epidermal/dermal Vδ1 vs panniculitic Vδ2) <ref name=":0" />
+|Different tissue compartments (epidermis/dermis vs  subcutaneous) correspond to distinct γδ T‑cell subsets (Vδ1 vs Vδ2). The cell‑of‑origin  influences mutational signatures (eg UV signature in Vδ1) and clinical  phenotype (Vδ2 more aggressive)<ref name=":0" />
+|'''Recurrent''' (5‑20%) — this  pattern applies in a subset of cases defined by tissue involvement and TCR  subtype.
+|D / P
+|No
+|This dichotomy may help stratify patients clinically (Vδ2  subtype worse prognosis) but is not currently part of formal diagnostic or  therapeutic guidelines.
+|-
+|'''Ultraviolet (UV) mutational signature in Vδ1  subtype''' <ref name=":0" />
+|The epidermal/dermal Vδ1 γδ T‑cell lymphomas exhibit a UV  signature in their mutation spectrum, likely reflecting skin localization and  UV exposure contributing to oncogenesis.
+|'''Recurrent''' (5‑20%) — seen in  Vδ1 cases but not all.
+|P
+|No
+|Could suggest etiology and may influence prognosis;  though not yet used for therapy selection.
+|-
+|'''Frequent deletions of 9p21.3 (CDKN2A region)'''  (part of the SCNV pattern) <ref name=":0" />
+|Loss of CDKN2A/p14^ARF leads to cell‑cycle deregulation,  loss of tumour suppressor control: a hallmark of many aggressive lymphomas
+|'''Common''' (>20%) (approx 61% of  cases)
+|P
+|No
+|Among the most prevalent genomic events in PCGDTCL —  potential prognostic marker though not yet guideline‑endorsed.
 |-
-|EXAMPLE
+|'''Multiple gains of oncogenic arms (e.g., 1q,  7q, 15q) and corresponding losses (eg 18q)''' <ref name=":0" />
+|Gains may increase dosage of oncogenes; losses may reduce  tumour suppressor dosage—together contributing to malignant phenotype
-Co-deletion of 1p and 18q
+|'''Recurrent''' (5‑20%) for specific  arm‑level changes (e.g., 1q gain ~33%, 7q ~39%, 15q ~33%)
-|Yes
+|P
 |No
+|These arm‑level events indicate complexity; may correlate  with poorer prognosis; not yet actionable in therapy.
+|-
+|'''TCR chain repertoire restriction / non‑random  Vγ or Vδ usage''' (eg Vγ3Vδ2 in panniculitic cases) <ref name=":0" />
+|Suggests antigen‑driven or tissue‐resident γδ T‑cell  proliferation; highlights non‑random selection of malignant clones
+|'''Recurrent''' (5‑20%) in defined  subtypes
+|D
 |No
-|EXAMPLE:
+|Might help refine subclassification of PCGDTCL; not  currently used in routine diagnostic algorithms.
-See chromosomal rearrangements table as this pattern is due to an unbalanced derivative translocation associated with oligodendroglioma (add reference).
 |}
-==Gene Mutations (SNV / INDEL)==
+==Gene Mutations (SNV/INDEL)==
-Put your text here and fill in the table <span style="color:#0070C0">(''Instructions: This table is not meant to be an exhaustive list; please include only genes/alterations that are recurrent and common as well either disease defining and/or clinically significant. Can include references 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.'') </span>
 {| class="wikitable sortable"
 |-
-!Gene; Genetic Alteration!!'''Presumed Mechanism (Tumor Suppressor Gene [TSG] / Oncogene / Other)'''!!'''Prevalence (COSMIC /  TCGA / Other)'''!!'''Concomitant Mutations'''!!'''Mutually Exclusive Mutations'''
+!Gene!!Genetic Alteration!!Tumor Suppressor Gene, Oncogene, Other!!Prevalence -
-!'''Diagnostic Significance (Yes, No or Unknown)'''
+Common >20%, Recurrent 5-20% or Rare <5% (Disease)
-!Prognostic Significance (Yes, No or Unknown)
+!Diagnostic, Prognostic, and Therapeutic Significance - D, P, T
-!Therapeutic Significance (Yes, No or Unknown)
+!Established Clinical Significance Per Guidelines - Yes or No (Source)
-!Notes
+!Clinical Relevance Details/Other Notes
 |-
-|EXAMPLE: TP53; Variable LOF mutations
+|'''STAT5B'''
+|Activating missense (e.g., p.N642H) → constitutive  downstream STAT5 signalling
-EXAMPLE:
+|Oncogene
+|Recurrent (~5‑20 %) — e.g., in the 2020 genomic study:  JAK/STAT mutations ~21 % of cases<ref name=":0" />
-EGFR; Exon 20 mutations
+|T / P: Therapeutic potential (JAK/STAT inhibition);  Prognostic implication (pathway addiction/resistance)
+|No
-EXAMPLE: BRAF; Activating mutations
+|Mutant STAT5B (especially N642H) shown to induce T‑cell  neoplasia in models; in PCGDTCL JAK/STAT addiction shown clinically <ref name=":1">{{Cite journal|last=Küçük|first=Can|last2=Jiang|first2=Bei|last3=Hu|first3=Xiaozhou|last4=Zhang|first4=Wenyan|last5=Chan|first5=John K. C.|last6=Xiao|first6=Wenming|last7=Lack|first7=Nathan|last8=Alkan|first8=Can|last9=Williams|first9=John C.|date=2015-01-14|title=Activating mutations of STAT5B and STAT3 in lymphomas derived from γδ-T or NK cells|url=https://pubmed.ncbi.nlm.nih.gov/25586472|journal=Nature Communications|volume=6|pages=6025|doi=10.1038/ncomms7025|issn=2041-1723|pmc=7743911|pmid=25586472}}</ref><ref name=":3">{{Cite journal|last=Zhang|first=Yue|last2=Yescas|first2=Julia A.|last3=Tefft|first3=Kristy|last4=Ng|first4=Spencer|last5=Qiu|first5=Kevin|last6=Wang|first6=Erica B.|last7=Akhtar|first7=Shifa|last8=Walker|first8=Addie|last9=Welborn|first9=Macartney|date=2025-04-15|title=Addiction of primary cutaneous γδ T cell lymphomas to JAK/STAT signaling|url=https://pubmed.ncbi.nlm.nih.gov/40231467|journal=The Journal of Clinical Investigation|volume=135|issue=8|pages=e180417|doi=10.1172/JCI180417|issn=1558-8238|pmc=11996904|pmid=40231467}}</ref>
-|EXAMPLE: TSG
+|-
-|EXAMPLE: 20% (COSMIC)
+|'''STAT3'''
+|Activating missense (SH2 domain) → constitutive STAT3  signalling
-EXAMPLE: 30% (add Reference)
+|Oncogene
-|EXAMPLE: IDH1 R123H
+|Rare (<5 %) to Recurrent (≈5‑10 %) (in NK/γδ‑T  lymphomas earlier)
-|EXAMPLE: EGFR amplification
+|T / P
-|
+|No
-|
+|Less frequent than STAT5B in PCGDTCL; part of JAK/STAT pathway involvement<ref name=":0" /><ref name=":1" />
-|
+|-
-|EXAMPLE:  Excludes hairy cell leukemia (HCL) (add reference).
+|'''JAK3'''
-<br />
+|Activating mutation (e.g., p.R657W) → JAK3 tyrosine  kinase activation
-|}
+|Oncogene
-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.
+|Rare (<5 %) (noted in the Daniels et al. cohort)
+|T
+|No
+|Supports JAK/STAT involvement; one case report showed  response to JAK inhibition<ref name=":3" />
+|-
+|'''KRAS'''
+|Activating hotspot mutations (e.g., G12D, Q61H, D119N) →  RAS/MAPK activation
+|Oncogene
+|Recurrent (~5‑20 %) — “KRAS was the most frequently  mutated oncogene” <ref name=":0" />
+|T / P
+|No
+|MAPK pathway appears relevant; patients with MAPK‑pathway  driver mutations had worse survival in the cohort<ref name=":0" />
+|-
+|'''NRAS'''
+|Activating hotspot mutation → RAS/MAPK activation
+|Oncogene
+|Rare (<5 %) to Recurrent (~5‑10 %)
+|T / P
+|No
+|Part of the same RAS/MAPK pathway as KRAS; less common.
+|-
+|'''MAPK1'''
+|Activating mutation → MAPK1 signalling activation
+|Oncogene
+|Rare (<5 %)
+|T
+|No
+|Also in MAPK pathway; limited data in PCGDTCL<ref name=":0" /><ref name=":1" />
+|-
+|'''MYC'''
+|Activating missense mutation (e.g., p.P74L) → MYC pathway  up‑regulation
+|Oncogene
+|Rare (<5 %)
+|P / T
+|No
+|MYC pathway involvement may contribute to the aggressive  phenotype; direct targeting not yet established<ref name=":0" />
+|-
+|'''MYCN'''
+|Activating mutation (e.g., p.G34R) → MYCN pathway  activation
+|Oncogene
+|Rare (<5 %)
+|P / T
+|No
+|Highlights involvement of MYC‑family beyond MYC itself in  this disease<ref name=":0" />
+|}Note: A more extensive list of mutations can be found in [https://www.cbioportal.org/ <u>cBioportal</u>], [https://cancer.sanger.ac.uk/cosmic <u>COSMIC</u>], and/or other databases. When applicable, gene-specific pages within the CCGA site directly link to pertinent external content.
 ==Epigenomic Alterations==
+N/A
-Put your text here
 ==Genes and Main Pathways Involved==
-Put your text here and fill in the table <span style="color:#0070C0">(''Instructions: Can include references in the table.'')</span>
 {| class="wikitable sortable"
 |-
 !Gene; Genetic Alteration!!Pathway!!Pathophysiologic Outcome
 |-
-|EXAMPLE: BRAF and MAP2K1; Activating mutations
+|DNMT3A (DNA methyltransferase)
-|EXAMPLE: MAPK signaling
+|Loss‑of‑function mutations or deletions → reduced de novo  DNA methylation; “epigenetic writer” defect (DNA methylation pathway)<ref name=":4">{{Cite journal|last=Zhang|first=Ping|last2=Zhang|first2=Mingzhi|date=2020-11-07|title=Epigenetic alterations and advancement of treatment in peripheral T-cell lymphoma|url=https://pubmed.ncbi.nlm.nih.gov/33160401|journal=Clinical Epigenetics|volume=12|issue=1|pages=169|doi=10.1186/s13148-020-00962-x|issn=1868-7083|pmc=7648940|pmid=33160401}}</ref>
-|EXAMPLE: Increased cell growth and proliferation
+|Deregulation of gene silencing; tumour suppressor genes  may remain unmethylated or aberrantly methylated → genomic instability,  aberrant T‑cell differentiation/activation
+|-
+|TET2 (methylcytosine dioxygenase)
+|Loss‑of‑function mutations → failure of DNA 5‑mC → 5‑hmC  demethylation (“epigenetic eraser” defect)<ref name=":4" />
+|Aberrant hypermethylation or demethylation patterns;  influences T‑cell development and malignant transformation (e.g., in T‑fh  lymphomas)
+|-
+|IDH2 (metabolic enzyme altering epigenome)
+|Gain‑of‑function mutation (e.g., R172) → produces 2‑hydroxyglutarate  → inhibits TET family → epigenetic dysregulation<ref name=":4" />
+|Oncometabolite‑driven methylation changes, impaired  differentiation, proliferation of malignant T cells
+|-
+|ARID1A (SWI/SNF chromatin‑remodeller)
+|Loss‑of‑function mutation/deletion → impaired nucleosome  remodelling, altered chromatin accessibility (“chromatin remodeller”)<ref name=":4" />
+|Reduced tumour‑suppressor gene expression due to  chromatin compaction; may influence immune microenvironment and genomic  instability
+|-
+|KMT2D / KMT2A (H3K4 methyltransferases)
+|Loss‑of‑function mutations (“histone‑writer” defect) →  decreased H3K4 methylation (activating mark)<ref name=":5">{{Cite journal|last=Ahmed|first=Nada|last2=Feldman|first2=Andrew L.|date=2020-02|title=Targeting epigenetic regulators in the treatment of T-cell lymphoma|url=https://pubmed.ncbi.nlm.nih.gov/31903826|journal=Expert Review of Hematology|volume=13|issue=2|pages=127–139|doi=10.1080/17474086.2020.1711732|issn=1747-4094|pmc=7110907|pmid=31903826}}</ref>
+|Impaired activation of gene expression programs  (differentiation, apoptosis) → contributes to malignant transformation
 |-
-|EXAMPLE: CDKN2A; Inactivating mutations
+|KDM6A (H3K27 demethylase)
-|EXAMPLE: Cell cycle regulation
+|Loss‑of‑function → accumulation of H3K27me3 (repressive  histone mark) (“histone‑eraser” defect)<ref name=":5" />
-|EXAMPLE: Unregulated cell division
+|Further chromatin repression of tumour‑suppressor genes;  may enhance survival of malignant T cells
 |-
-|EXAMPLE:  KMT2C and ARID1A; Inactivating mutations
+|EZH2 (PRC2 complex methyltransferase)
-|EXAMPLE:  Histone modification, chromatin remodeling
+|Overexpression/gain of function → increased H3K27me3  (“histone‑writer” overactivity) <ref name=":4" />
-|EXAMPLE:  Abnormal gene expression program
+|Enhanced silencing of differentiation/apoptosis genes;  contributes to aggressive lymphoma phenotypes
+|-
+|CREBBP / EP300 (histone acetyl‑transferases)
+|Loss‑of‑function mutations (“histone‑writer” defect) →  reduced histone acetylation and gene activation<ref name=":5" />
+|Diminished transcriptional activation of tumour‑suppressor/immune  genes; may drive malignant progression
+|-
+|DNA methylation of specific tumour‑suppressor loci (e.g.,  CDKN2A promoter; FAS promoter)
+|Hypermethylation of promoter CpG islands → silencing of tumor suppressor / apoptosis‑initiator genes<ref>{{Cite journal|last=Hara|first=Natsumi|last2=Sawada|first2=Yu|date=2022-03-24|title=Epigenetics of Cutaneous T-Cell Lymphomas|url=https://pubmed.ncbi.nlm.nih.gov/35408897|journal=International Journal of Molecular Sciences|volume=23|issue=7|pages=3538|doi=10.3390/ijms23073538|issn=1422-0067|pmc=8998216|pmid=35408897}}</ref>
+|Loss of cell‑cycle control or apoptosis leads to  malignant T‑cell survival/proliferation
 |}
 ==Genetic Diagnostic Testing Methods==
-Put your text here
+{| class="wikitable"
+|'''Method'''
+|'''Description'''
+|'''Type of Alteration Detected'''
+|'''Advantages'''
+|'''Limitations'''
+|'''Clinical Use in PCGDTCL'''
+|-
+|'''Next-Generation Sequencing (NGS)'''
+|High-throughput sequencing of targeted gene panels,  whole-exome, or whole-genome sequencing
+|SNVs, INDELs, copy number variants (CNVs), some fusions  (if RNA-seq included)
+|Comprehensive mutation detection; scalable; can detect  multiple variants simultaneously
+|Requires high-quality DNA/RNA; bioinformatics expertise  needed; cost-intensive
+|Main tool for mutational profiling in PCGDTCL; used in  research and increasingly in clinical labs
+|-
+|'''Targeted Gene Panels (amplicon or hybrid  capture-based)'''
+|Sequencing of a defined set of genes known to be relevant
+|SNVs, INDELs, limited CNVs, hotspot fusions (if included)
+|Faster, cheaper than WES/WGS; focused on clinically  relevant genes
+|May miss novel or unexpected mutations; limited to panel  content
+|Often used clinically to screen for mutations in  JAK/STAT, RAS pathways in PCGDTCL
+|-
+|'''Fluorescence In Situ Hybridization (FISH)'''
+|DNA probes hybridize to metaphase or interphase  chromosomes
+|Structural chromosomal alterations, gene fusions,  amplifications, deletions
+|Visualizes gene rearrangements and copy number changes;  established clinical use
+|Limited to known targets; low resolution; labor-intensive
+|Used to detect known translocations or gene  amplifications (e.g., MYC) in lymphoma diagnosis
+|-
+|'''Array Comparative Genomic Hybridization  (aCGH) / SNP Arrays'''
+|Genome-wide detection of copy number alterations and LOH
+|Copy number gains, losses, LOH (Loss of heterozygosity)
+|Genome-wide coverage; detects submicroscopic CNVs
+|Cannot detect balanced translocations or point mutations;  resolution depends on array density
+|Useful for detecting large chromosomal alterations in  lymphoma samples
+|-
+|'''RNA Sequencing (RNA-Seq)'''
+|Sequencing of transcriptome
+|Gene fusions, splice variants, expression levels
+|Detects novel and known fusions; measures gene  expression; alternative splicing
+|RNA quality sensitive; bioinformatics expertise needed
+|Research use for identifying novel fusion partners or  expression signatures in PCGDTCL
+|-
+|'''Sanger Sequencing'''
+|Chain termination sequencing of PCR-amplified regions
+|SNVs and small indels
+|Gold standard for validation; high accuracy
+|Low throughput; not suitable for large panels
+|Used to confirm NGS-identified mutations
+|-
+|'''Digital Droplet PCR (ddPCR) / qPCR'''
+|Highly sensitive quantification of known mutations or  gene rearrangements
+|Known point mutations, copy number changes
+|Very sensitive, quantitative; fast turnaround
+|Limited to known mutations; not comprehensive
+|Useful for monitoring known mutations (e.g., STAT5B  N642H) in minimal residual disease (MRD) or treatment response
+|-
+|'''Immunohistochemistry (IHC)'''  (surrogate genetic marker)
+|Antibody staining of protein expression
+|Protein expression reflecting genetic alterations (e.g.,  pSTAT5B, MYC)
+|Widely available; easy to implement
+|Indirect; may not perfectly correlate with mutation  status
+|Supportive role in diagnosis and prognosis, not  definitive genetic test
+|}
 ==Familial Forms==
+There are currently '''no well-established familial or hereditary forms''' described in the literature.
-Put your text here <span style="color:#0070C0">(''Instructions: Include associated hereditary conditions/syndromes that cause this entity or are caused by this entity.'') </span>
 ==Additional Information==
+N/A
-Put your text here
 ==Links==
-Put your text placeholder here (or anywhere appropriate on the page) and use the "Link" icon at the top of the page <span style="color:#0070C0">(''Instructions: Once you have a text placeholder entered to which you want to add a link, highlight that text, select the "Link" icon at the top of the page, and search the name of the internal page to which you want to link this text, or enter an external internet address including the "<nowiki>http://www</nowiki>." portion.'')</span>
+N/A
 ==References==
-(use the "Cite" icon at the top of the page) <span style="color:#0070C0">(''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.''</span> <span style="color:#0070C0">''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''</span><span style="color:#0070C0">''.''</span><span style="color:#0070C0">) </span> <references />
+<references />
+==Notes==
+<nowiki>*</nowiki>''Citation of this Page'': Azimpouran M, Kitahara S. “Primary cutaneous gamma/delta T-cell lymphoma”. Compendium of Cancer Genome Aberrations (CCGA), Cancer Genomics Consortium (CGC), updated {{REVISIONMONTH}}/{{REVISIONDAY}}/{{REVISIONYEAR}}, <nowiki>https://ccga.io/index.php/HAEM5:Primary_cutaneous_gamma/delta_T-cell_lymphoma</nowiki>.
-'''EXAMPLE Book'''
-#Arber DA, et al., (2017). Acute myeloid leukaemia with recurrent genetic abnormalities, 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, p129-171.
+<nowiki>*</nowiki>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 [[Leadership|''<u>Associate Editor</u>'']] or other CCGA representative.  When pages have a major update, the new author will be acknowledged at the beginning of the page, and those who contributed previously will be acknowledged below as a prior author.
-==Notes==
+Prior Author(s): N/A
-<nowiki>*</nowiki>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.
+[[Category:HAEM5]]
-<nowiki>*</nowiki>''Citation of this Page'': “Primary cutaneous gamma/delta T-cell lymphoma”. Compendium of Cancer Genome Aberrations (CCGA), Cancer Genomics Consortium (CGC), updated {{REVISIONMONTH}}/{{REVISIONDAY}}/{{REVISIONYEAR}}, <nowiki>https://ccga.io/index.php/HAEM5:Primary_cutaneous_gamma/delta_T-cell_lymphoma</nowiki>.
+[[Category:DISEASE]]
-[[Category:HAEM5]][[Category:DISEASE]][[Category:Diseases P]]
+[[Category:Diseases P]]

HAEM5:Primary cutaneous gamma/delta T-cell lymphoma: Difference between revisions

Latest revision as of 22:48, 6 January 2026

Primary Author(s)*

WHO Classification of Disease

Related Terminology

Gene Rearrangements

Individual Region Genomic Gain/Loss/LOH

Characteristic Chromosomal or Other Global Mutational Patterns

Gene Mutations (SNV/INDEL)

Epigenomic Alterations

Genes and Main Pathways Involved

Genetic Diagnostic Testing Methods

Familial Forms

Additional Information

Links

References

Notes

Navigation menu

Search