Immunophenotyping of Nodal Peripheral T-cell Lymphomas and its Association with Epstein-Barr Virus

Background: immunophenotyping in the rare group of nodal peripheral t-cell lymphomas (ptcl) exposes interesting features such as t-cell marker downregulation and paradoxically, the presence of reactive, clustered large sized cd20 positive b-cells (b-cell proliferation). epstein-barr virus (ebv) has been suggested as a putative etiology in pathogenesis of b-cell lymphoma. we aimed to review the immunohistochemical profile of patients with nodal ptcl with emphasis on t-cell markers and immunophenotypic aberrations, cd20 positive large b-cells, ki-67 scores (as a measure of proliferation index) and to assess the association of epstein-barr virus in various subtypes of nodal ptcl. methods: 80 cases of nodal ptcl diagnosed during january 2008-june 2013 were included in the study. relevant clinical and hematological data were collected. using streptavidin-biotin-peroxidase system, staining for cd2, cd3, cd4, cd5, cd7, cd8, cd20,ebv-lmp1 and ki-67 were performed on all blocks.cd10,cd23,bcl-6, cd30 and alk-1 were used in relevant cases. results: 95% of patients had downregulation of at least one t-cell marker (maximum: cd7 (87%), minimum: cd3 and cd5- 9% each). 29 patients (36%) showed markers of b-cell proliferation. only five patients (6%) were positive for ebv-lmp1. there was a significant association between ebv-lmp1 positivity and b-cell proliferation (p=0.002). 17 patients (21%) had high ki-67 index (≥80%). conclusion: nodal ptcl showed frequent downregulation of t-cell markers. ebv was only infrequently positive in these lymphomas. clusters of large b-cells need to be noted in pathology reports and ebv needs to be tested for in such cases.