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==Definition / Description of Disease==

==Definition / Description of Disease==

An indolent primary cutaneous CD4+ T-cell lymphoproliferative disorder for which conservative treatment such as excision and local radiation is known to be effective. They express at least one follicular T-helper (TFH) marker, except for CD10, and thus is suspected to arise from TFH cells.   

An indolent primary cutaneous peripheral CD4+ T-cell lymphoproliferative disorder for which conservative treatment such as excision and local radiation therapy is known to be effective.  

 

They express at least one follicular T-helper (TFH) marker, except for CD10. 

 

The differential diagnosis includes<ref name=":1" /><ref name=":4">Jaffe, E. et al. (2017). Hematopathology (2nd ed.). Elsevier.</ref> 

 

* reactive benign cutaneous lymphoid proliferation  

Put your text here <span style="color:#0070C0">(''Instructions: Brief description of approximately one paragraph - include disease context relative to other WHO classification categories, diagnostic criteria if applicable, and differential diagnosis if applicable. Other classifications can be referenced for comparison.'') </span>

Put your text here <span style="color:#0070C0">(''Instructions: Brief description of approximately one paragraph - include disease context relative to other WHO classification categories, diagnostic criteria if applicable, and differential diagnosis if applicable. Other classifications can be referenced for comparison.'') </span>

==Synonyms / Terminology==

==Synonyms / Terminology==

Primary cutaneous CD4+ small/medium T-cell lymphoma (not preferred due to indolent clinical course)<ref name=":0">Swerdlow, S.H.  et al. WHO classification of tumours of haematopoietic and lymphoid tissues (4th Ed), pp.401</ref>

Primary cutaneous CD4+ small/medium T-cell lymphoma (not preferred due to indolent clinical course)<ref name=":0">Swerdlow, S.H.  et al. (2017). WHO classification of tumours of haematopoietic and lymphoid tissues (4th Ed). IARC</ref>

==Epidemiology / Prevalence==

==Epidemiology / Prevalence==

Previously considered an uncommon disease but may be underestimated.  

Previously considered an uncommon disease but may be underestimated.  

Comprising up to 6% of cutaneous T-cell lymphomas (CTCLs). <ref>{{Cite journal|last=Willemze|first=Rein|last2=Cerroni|first2=Lorenzo|last3=Kempf|first3=Werner|last4=Berti|first4=Emilio|last5=Facchetti|first5=Fabio|last6=Swerdlow|first6=Steven H.|last7=Jaffe|first7=Elaine S.|date=2019-04-18|title=The 2018 update of the WHO-EORTC classification for primary cutaneous lymphomas|url=https://pubmed.ncbi.nlm.nih.gov/30635287/|journal=Blood|volume=133|issue=16|pages=1703–1714|doi=10.1182/blood-2018-11-881268|issn=1528-0020|pmc=6473500|pmid=30635287}}</ref>

Comprising up to 6% of CTCLs. <ref>{{Cite journal|last=Willemze|first=Rein|last2=Cerroni|first2=Lorenzo|last3=Kempf|first3=Werner|last4=Berti|first4=Emilio|last5=Facchetti|first5=Fabio|last6=Swerdlow|first6=Steven H.|last7=Jaffe|first7=Elaine S.|date=2019-04-18|title=The 2018 update of the WHO-EORTC classification for primary cutaneous lymphomas|url=https://pubmed.ncbi.nlm.nih.gov/30635287/|journal=Blood|volume=133|issue=16|pages=1703–1714|doi=10.1182/blood-2018-11-881268|issn=1528-0020|pmc=6473500|pmid=30635287}}</ref>

One study reported local prevalence of 12.5% of all CTCLs, making it the second most common cutaneous lymphoma following mycosis fungoides.<ref name=":1" />

One study reported local prevalence of 12.5% of all CTCLs, making it the second most common cutaneous lymphoma following mycosis fungoides.<ref name=":1" />

Slow growing

Slow growing

Solitary skin nodule/papule/plaque<ref name=":1" /><ref name=":0" />

Solitary skin nodule/papule/plaque, reddish/purple<ref name=":4" /><ref name=":1" /><ref name=":0" />

Multiple lesions in a small number of patients<ref name=":1" /><ref name=":0" />

Multiple lesions in a small number of patients<ref name=":1" /><ref name=":0" />

*Dense dermal lymphoid infiltrate, often with nodular or diffuse pattern<ref name=":2">{{Cite journal|last=Beltraminelli|first=Helmut|last2=Leinweber|first2=Bernd|last3=Kerl|first3=Helmut|last4=Cerroni|first4=Lorenzo|date=2009-06|title=Primary cutaneous CD4+ small-/medium-sized pleomorphic T-cell lymphoma: a cutaneous nodular proliferation of pleomorphic T lymphocytes of undetermined significance? A study of 136 cases|url=https://pubmed.ncbi.nlm.nih.gov/19461234|journal=The American Journal of Dermatopathology|volume=31|issue=4|pages=317–322|doi=10.1097/DAD.0b013e31819f19bb|issn=1533-0311|pmid=19461234}}</ref><ref name=":3">{{Cite journal|last=Cetinözman|first=Fatma|last2=Jansen|first2=Patty M.|last3=Willemze|first3=Rein|date=2012-01|title=Expression of programmed death-1 in primary cutaneous CD4-positive small/medium-sized pleomorphic T-cell lymphoma, cutaneous pseudo-T-cell lymphoma, and other types of cutaneous T-cell lymphoma|url=https://pubmed.ncbi.nlm.nih.gov/21989349|journal=The American Journal of Surgical Pathology|volume=36|issue=1|pages=109–116|doi=10.1097/PAS.0b013e318230df87|issn=1532-0979|pmid=21989349}}</ref>

*Dense dermal lymphoid infiltrate, often with nodular or diffuse pattern<ref name=":2">{{Cite journal|last=Beltraminelli|first=Helmut|last2=Leinweber|first2=Bernd|last3=Kerl|first3=Helmut|last4=Cerroni|first4=Lorenzo|date=2009-06|title=Primary cutaneous CD4+ small-/medium-sized pleomorphic T-cell lymphoma: a cutaneous nodular proliferation of pleomorphic T lymphocytes of undetermined significance? A study of 136 cases|url=https://pubmed.ncbi.nlm.nih.gov/19461234|journal=The American Journal of Dermatopathology|volume=31|issue=4|pages=317–322|doi=10.1097/DAD.0b013e31819f19bb|issn=1533-0311|pmid=19461234}}</ref><ref name=":3">{{Cite journal|last=Cetinözman|first=Fatma|last2=Jansen|first2=Patty M.|last3=Willemze|first3=Rein|date=2012-01|title=Expression of programmed death-1 in primary cutaneous CD4-positive small/medium-sized pleomorphic T-cell lymphoma, cutaneous pseudo-T-cell lymphoma, and other types of cutaneous T-cell lymphoma|url=https://pubmed.ncbi.nlm.nih.gov/21989349|journal=The American Journal of Surgical Pathology|volume=36|issue=1|pages=109–116|doi=10.1097/PAS.0b013e318230df87|issn=1532-0979|pmid=21989349}}</ref>

*Tends to extend to subcutaneous tissue<ref name=":3" /><ref name=":2" />

*Tends to extend to superficial subcutaneous tissue<ref name=":3" /><ref name=":2" />

*Lack significant epidermotropism and folliculotropism<ref name=":3" />

*Lack significant epidermotropism and folliculotropism<ref name=":3" />

*Predominantly small/medium-size T-cells with mild-moderate cytological atypia<ref name=":3" /><ref name=":2" /><ref name=":1" /><ref name=":0" />

*Predominantly small/medium-size T-cells with mild-moderate cytological atypia<ref name=":3" /><ref name=":2" /><ref name=":1" /><ref name=":0" />

|}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.

|}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.

==Epigenomic Alterations==

==Epigenomic Alterations==

N/

N/A

==Genes and Main Pathways Involved==

==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. Do not delete table.'')</span>

Put your text here and fill in the table <span style="color:#0070C0">(''Instructions: Can include references in the table. Do not delete table.'')</span>

!Gene; Genetic Alteration!!Pathway!!Pathophysiologic Outcome

!Gene; Genetic Alteration!!Pathway!!Pathophysiologic Outcome

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|<span class="blue-text">EXAMPLE:</span> ''BRAF'' and ''MAP2K1''; Activating mutations

|Not found

|N/A

|N/A

|<span class="blue-text">EXAMPLE:</span> Histone modification, chromatin remodeling

|<span class="blue-text">EXAMPLE:</span> Abnormal gene expression program

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==Genetic Diagnostic Testing Methods==

==Genetic Diagnostic Testing Methods==

PCR for clonal T-cell receptor gene rearrangement (clonal rearrangement present in majority of cases). <ref name=":1" />

PCR for clonal T-cell receptor gene rearrangement (clonal rearrangement present in majority of cases). <ref name=":1" /><ref name=":3" />

==Familial Forms==

==Familial Forms==

<span style="color:#0070C0">N/A </span>

<span style="color:#0070C0">N/A </span>