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Published on: March 5, 2019
How I Diagnose Mature T-Cell Proliferations by Flow Cytometry
Steven H Kroft1, Alexandra M Harrington1
1Medical College of Wisconsin, Milwaukee, WI, USA.
Insights
Flow cytometry aids in diagnosing mature T-cell neoplasms by assessing immunophenotypic aberrancy and clonality. Understanding T-cell responses and clinical context is crucial for accurate interpretation of flow cytometry results.
Area of Science:
- Hematopathology
- Immunology
- Oncology
Background:
- Mature T-cell neoplasms present diagnostic challenges in hematopathology.
- Flow cytometry is increasingly utilized for T-cell assessment.
Purpose of the Study:
- To discuss the application of flow cytometry in evaluating mature T-cell proliferations.
- To provide a framework including cases, normal T-cell subsets, and diagnostic pitfalls.
Main Methods:
- Review of flow cytometry principles for T-cell evaluation.
- Analysis of immunophenotypic aberrancy and clonality.
- Examination of normal and reactive T-cell subset antigen expression patterns.
Main Results:
- Immunophenotypic aberrancy directly reflects neoplastic phenotype, distinguishing it from clonal expansion in reactive/neoplastic states.
- Characteristic antigen expression patterns exist for major and minor T-cell subsets.
- Certain antigen expression patterns are rare or absent in reactive T cells, aiding diagnosis.
Conclusions:
- Flow cytometry is a valuable tool for diagnosing mature T-cell proliferations.
- Accurate interpretation requires thorough knowledge of T-cell immune responses.
- Awareness of the clinical context is essential for effective use of flow cytometry.
Objectives:
Mature T-cell neoplasms are a challenging area of diagnostic hematopathology. Flow cytometry has emerged as a useful technique for T-cell assessment.
Methods:
We discuss the application of flow cytometry to the evaluation of mature T-cell proliferations, to include illustrative cases, theoretical framework, detailed review of normal and reactive T-cell subsets, and examination of diagnostic pitfalls.
Results:
Immunophenotypic aberrancy can be construed as a direct expression of the neoplastic phenotype, in contrast to clonal expansion, which is seen in reactive and neoplastic T-cell proliferations. Major and minor T-cell subsets show characteristic patterns of antigen expression. Reactive states can manifest expansions of normal minor subsets and also show alterations of antigen expression on certain populations. However, some patterns of antigen expression are either never or very rarely encountered in reactive T cells. Flow cytometric tools are now available to directly assess clonality in specific T-cell populations. Technical and biological pitfalls may complicate the interpretation of T-cell flow cytometry.
Conclusions:
Flow cytometry is a very useful tool in the diagnostic armamentarium for the assessment of mature T-cell proliferations, but it must be interpreted based on a thorough knowledge of the T-cell immune response, as well as an awareness of clinical context.
