Update on primary cutaneous T-cell lymphomas rare subtypes.

Area of Science:

• Dermatology
• Hematology
• Oncology

Background:

• Rare subtypes of cutaneous T-cell lymphomas (CTCL) were previously provisional.
• These entities are now recognized as distinct in the 5th World Health Organization classification.

Purpose of the Study:

• To provide an updated summary of rare CTCL subtypes.
• To focus on clinical, histological, and genomic characteristics.
• To review classification and potential treatment strategies.

Main Methods:

• Literature review of clinical, histological, and genomic data.
• Analysis of the 5th World Health Organization classification of hematolymphoid tumors.
• Synthesis of current knowledge on rare CTCL subtypes.

Main Results:

• Four rare CTCL subtypes are now distinct entities: primary cutaneous γδ T-cell lymphoma, primary cutaneous CD8+ aggressive epidermotropic cytotoxic T-cell lymphoma, primary cutaneous CD4+ small/medium T-cell lymphoproliferative disorders, and primary cutaneous acral CD8+ T-cell lymphoma.
• Updated information on the classification of these uncommon lymphomas is presented.
• Current understanding of their clinical, histological, and genomic features is summarized.

Conclusions:

• The 5th WHO classification formally recognizes these rare CTCL subtypes.
• Further research into their specific characteristics is warranted.
• This review provides a foundation for exploring targeted treatment strategies.