Flow cytometry immunophenotypic diagnosis of B-cell non-Hodgkin lymphomas on fine-needle aspirate of lymph node

Introduction: B-cell non-Hodgkin lymphomas (NHLs) are divided into low and high grade, typically corresponding to indolent (slow-growing) lymphomas and aggressive lymphomas, respectively. In recent years, flow cytometric immunophenotyping (FCI) has become an important tool in the diagnosis of mature lymphoid neoplasms and the determination of prognosis in selected cases. Objective: The aim of this study was to diagnose B-cell NHL by FCI on fine-needle aspiration (FNA) of lymph node following immunophenotypic diagnostic criteria based on the expression of CD markers. Patients and Methods: All samples were preliminary assessed by FNA cytology as NHL or lymphoproliferative disorder. 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 the WHO classification. Wherever possible, the diagnoses were compared with available immunohistochemistry (IHC). Results: During 1-year period (from March 2016 to February 2017), 31 cases of NHL were diagnosed by FCI of which 16 (51.6%) cases were B-cell NHL. Among 16 cases of B-cell lymphoma, 1 case (6.25%) was follicular lymphoma; 10 cases (62.5%) were diffuse large B-cell lymphoma (DLBCL); 2 cases (12.5%) were mantle cell lymphoma; 2 cases (12.5%) were small lymphocytic lymphoma; and 1 case (6.25%) was found to be B-cell prolymphocytic lymphoma. Monoclonal or polyclonal B cells with positive CD45, CD19, CD20, CD79a, and CD79b were found in all types. There was variation in CD5, CD23, CD10, Bcl-2, and FCM7. Identification by FCI is 40.3% higher in DLBCL than IHC. Conclusion: Application of FCI from FNA sample enhanced the diagnostic potential and avoiding the need for invasive surgical biopsies. Misdiagnosis can be avoided and help the physician to plan the treatment regimen accordingly.