Phenotypic and cytotoxic characteristics of peripheral T-cell and NK-cell lymphomas in relation to Epstein-Barr virus association

Aims We investigated the phenotypic and cytotoxic characteristics of different types of peripheral T‐cell and NK‐cell lymphomas and correlated the findings of cytotoxic phenotype with Epstein–Barr virus (EBV) association. Methods and results Eighty cases of peripheral T‐cell and NK‐cell lymphomas, classified according to the REAL classification, were investigated for cytotoxic phenotype (by studying T‐cell intracellular antigen‐1 (TIA‐1) expression immunohistochemically) and EBV association (by in situ hybridization for EBV‐encoded small non‐polyadenylated RNAs), and the results were correlated with the specific clinicopathological types and the immunophenotype with special emphasis on CD56 expression and CD4/CD8 status. Overall, 39/80 cases (49%) expressed TIA‐1. Angiocentric lymphoma (23/24 cases; 96%), aggressive NK‐cell leukaemia (‘large granular lymphocyte (LGL) leukaemia’) (3/3 cases; 100%), intestinal T‐cell lymphoma (5/6 cases; 83%) and anaplastic large cell lymphoma (4/6 cases; 67%) were the major subtypes showing a cytotoxic phenotype. Only four of the 27 cases (15%) of peripheral T‐cell lymphoma, unspecified, were TIA‐1+ , while all the seven cases of angioimmunoblastic T‐cell lymphoma, six cases of mycosis fungoides and one case of adult T‐cell lymphoma/leukaemia were TIA‐1−. Conclusions Within the group of peripheral T‐cell and NK‐cell lymphomas, angiocentric lymphoma, aggressive NK‐cell leukaemia (‘LGL leukaemia’), intestinal T‐cell lymphoma and anaplastic large cell lymphoma are the major subtypes displaying a cytotoxic phenotype. The relationships between the cytotoxic phenotype and EBV association, CD56 expression or CD4/CD8 status are secondary to the relationship between cytotoxic phenotype and specific lymphoma subtype.