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 diffe rent types of peripheral T-cell and NK-cell lymphomas and correlated the fi ndings of cytotoxic phenotype with Epstein-Barr virus (EBV) association. Methods and results: Eighty cases of peripheral T-cell and NK-cell lymphoma s, classified according to the REAL classification, were investigated for c ytotoxic phenotype (by studying T-cell intracellular antigen-1 (TIA-1) expr ession immunohistochemically) and EBV association (by in situ hybridization for EBV-encoded small non-polyadenylated RNAs), and the results were corre lated with the specific clinicopathological types and the immunophenotype w ith special emphasis on CD56 expression and CD4/CD8 status. Overall, 39/80 cases (49%) expressed TIA-1. Angiocentric lymphoma (23/24 cases; 96%), aggr essive NK-cell leukaemia ('large granular lymphocyte (LGL) leukaemia') (3/3 cases; 100%), intestinal T-cell lymphoma (5/6 cases; 83%) and anaplastic l arge cell lymphoma (4/6 cases; 67%) were the major subtypes showing a cytot oxic phenotype. Only four of the 27 cases (15%) of peripheral T-cell lympho ma, unspecified, were TIA-1+, while all the seven cases of angioimmunoblast ic 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, a ngiocentric lymphoma, aggressive NK-cell leukaemia ('LGL leukaemia'), intes tinal T-cell lymphoma and anaplastic large cell lymphoma are the major subt ypes displaying a cytotoxic phenotype. The relationships between the cytoto xic phenotype and EBV association, CD56 expression or CD4/CD8 status are se condary to the relationship between cytotoxic phenotype and specific lympho ma subtype.