Morphologic and immunologic characterization of 50 peripheral T-cell lymphomas.

Area of Science:

• Hematology
• Immunology
• Oncology

Background:

• T-cell lymphomas are a diverse group of lymphoid malignancies.
• Accurate classification requires integrating morphological and immunophenotypic data.

Purpose of the Study:

• To characterize the morphological and immunophenotypic features of T-cell lymphomas.
• To identify potential diagnostic markers for T-cell lymphomas.

Main Methods:

• Morphological analysis of 50 T-cell lymphomas (excluding mycosis fungoides and lymphoblastic lymphoma).
• Immunohistochemical analysis using monoclonal antibodies for T-cell differentiation antigens on fresh frozen tissue.
• Evaluation of pan-T antigens (Leu 1, 4, 5) and T-cell antigen Leu 9 expression.

Main Results:

• Histological subtypes included large-cell immunoblastic (36%), diffuse large-cell (26%), diffuse mixed (22%), and monomorphic medium-sized-cell (16%).
• Immunophenotypes showed helper (64%), cytotoxic/suppressor (12%), dual (8%), and null (16%) phenotypes.
• Loss of pan-T antigens (Leu 1, 4, 5) or Leu 9 was observed in 32 cases (64%), with Leu 1/Leu 9 loss in 46%, Leu 4 loss in 26%, and Leu 5 loss in 24%.
• No correlation was found between histological subtype and immunophenotype.
• Approximately 75% of lymphomas expressed Ia antigens.

Conclusions:

• Morphological and immunophenotypic classifications of T-cell lymphomas are distinct.
• Loss of pan-T antigens (Leu 1, 4, 5) or Leu 9 is a frequent finding and may aid in diagnosing T-cell lymphomas.