[T and NK cell peripheral tumors]

Area of Science:

• Immunology
• Oncology
• Pathology

Background:

• Peripheral T-cell lymphomas (PTCLs) originate from T-cells expressing CD3 antigen and T-cell receptor (TCR) alpha/beta, with a minor population expressing TCR gamma/delta.
• Natural Killer (NK) cells are distinct, lacking TCR gene rearrangement and expressing CD56, though a continuum exists between T and NK cells.
• Cytotoxic proteins like TIA-1, granzyme-B, and perforin are commonly found in NK cells and associated tumors.

Purpose of the Study:

• To differentiate between T-cell lymphomas and NK-cell lymphomas based on cellular markers and protein expression.
• To analyze the prognostic implications of cell size, morphology, and specific antigen expression in T/NK lymphomas.
• To review recent entities of extra-nodular T-cell lymphomas and their geographical distribution.

Main Methods:

• Immunophenotyping using CD3, TCR alpha/beta, TCR gamma/delta, and CD56.
• Assessment of cytotoxic proteins including TIA-1, granzyme-B, and perforin.
• Morphological analysis of tumor cells and correlation with clinical outcomes.

Main Results:

• Prognosis of T-cell tumors cannot be solely determined by cell size; small cell T/NK lymphomas are highly aggressive with poor patient prognosis.
• Large cell T-cell lymphomas of the skin, CD30 positive, exhibit a mild clinical course and favorable prognosis.
• Rare extra-nodular T-cell lymphomas, such as angiocentric NK/T lymphoma and hepatosplenic gamma/delta T lymphoma, are discussed, with some prevalent in specific regions or in immunosuppressed individuals.

Conclusions:

• T-cell and NK-cell lymphomas present a spectrum of disease with variable clinical behavior and prognosis.
• Accurate diagnosis requires a combination of immunophenotyping, assessment of cytotoxic markers, and morphological evaluation.
• Emerging entities of T/NK lymphomas necessitate awareness, particularly in specific patient populations and geographical areas.