AN APPROACH TO DIAGNOSIS OF T-CELL AND NK-CELL NON - HODGKIN LYMPHOMAS BY FLOW CYTOMETRIC IMMUNOPHENOTYPING ON FINE NEEDLE ASPIRATE OF LYMPH NODE

of Lymphoid Neoplasms are defined as clonal tumors of mature and immature B cells, T cells or natural killer (NK) cells at various stages differentiation. Because cells immunophenotypic and functional properties with T cells, these two classes of together. [1] T-cell lymphomas represents approximately 10% of Non-Hodgkin lymphomas. T-cell/NK-cell Non-Hodgkin lymphoma subtypes are about 29. [3] The major subtypes are - 1) Peripheral T-cell Lymphoma-NOS(25.9%) ABSTRACT Introduction: Lymphoid Neoplasms are defined as clonal tumors of mature and immature B cells, T cells or natural killer (NK) cells at various stages of differentiation. Because NK cells are closely related and share some immunophenotypic and functional properties with T cells, these two classes of neoplasms considered together. Distinct T-cell/NK-cell NHL subtypes have unique characteristics and often warrant individualized diagnostic and therapeutic treatment strategies. Objective : The aim of this study was to diagnose T-cell/NK-cell Non-Hodgkin lymphoma by Flow cytometric immunophenotyping (FCI) on fine needle aspirate (FNA) of lymphnode following immunophenotypic diagnostic criteria based on expression of CD markers. Method: All samples were preliminary assessed by fine needle aspiration cytology (FNAC) as NHL or lymphoproliferative disorder (LPD). FCI was performed with a complete panel of antibodies (CD3, CD4, CD8, CD5, CD7, CD10, CD19, CD20, CD23, CD22, CD25, CD30, CD45, CD79a, CD79b, CD95, CD56, FMC7, CD40, CD15, Kappa, Lambda and Bcl-2) by dual color flow cytometry. FCI data were interpreted to diagnose and subclassify NHL according to WHO classification. Wherever possible the diagnoses were compared with available immunohistochemistry (IHC) histopathology reports. Result: During one year period (from March 2016 to February 2017) 31 cases of Non-Hodgkin lymphoma were diagnosed by FCI of which 13 (41.9%) cases were T-cell type of Non-Hodgkin lymphoma and 2 (6.5%) cases were Aggressive Natural killer cell leukemia. Among T-cell type NHL, 3(23.1%) cases were Peripheral T-cell lymphoma (NOS), 3(23.1%) cases were T-lymphoblastic lymphoma, 4(30.8%) cases were Angio-immunoblastic T-cell lymphoma, 2(15.3%) cases were Anaplastic large cell lymphoma, and 1(7.7%) case was Adult T- cell lymphoma. CD45 and both membrane and cytoplasmic CD3 were positive in all types of T-cell NHL except T-lymphoblastic lymphoma, in which membrane CD3 negative but cytoplasmic CD3 was positive. There were variation in CD4, CD8, CD5, CD7, CD10, and CD30 markers. In case of Aggressive NK-cell NHL, CD56 and BCL2 was found to be positive. Identification by FCI is 23.4% higher in T-cell lymphoma than IHC and is 27.8% higher than histopathology. No NK-cell type of Non-Hodgkin lymphoma was detected by histopathology. Conclusion: By histopathology, it is almost impossible to detect all subtypes specially T-cell and NK-cell type of Non-Hodgkin lymphoma but flow cytometric immunophenotyping can directly recognize the different subtypes associated with disease progression by detecting specific CD markers.