The Utility of DNA Cell Cycle Analysis by Flow Cytometry in Differentiating Follicular -Lymphoma from CD10+ Diffused large B cell Lymphoma

Introduction: Differentiating Follicular lymphoma (FL) from CD10+ Diffused Large B cell Lymphoma (DLBCL) could be a diagnostic challenge. Previous observations suggested that DNA aneuploidy is more common in aggressive then in indolent Non-Hodgkin lymphoma (NHLs) (1). Aim: Here we investigated the utilization of DNA cell cycle analysis by flow cytometry as a possible biomarker that could help in differentiating between Follicular lymphoma (FL) and CD10+ Diffused Large B cell Lymphoma. Methods: Thirty nine CD10+ NHLs specimens were submitted to our flow cytometry laboratory between the 10.01.16 and 10.04.18. All specimens were kept fresh or in RPMI media without preservatives until analyzed within 24h of isolation. DNA purification and analysis was performed using the Coulter DNA prep REAGENT Kit (Ref# 6607055) and the Backman-coulter Navios instrument. Results: A total of 37 specimens; 24 lymph nodes (LN), 8 bone marrow (BM), 2 peripheral blood (PB), 2 pleural effusions and 1 peritoneal effusion are included in this study. Two samples that contained less than 10% malignant cells (1 BM and 1 Pleural effusion) were excluded. Histo-pathological and cyto-pathological analysis confirmed the diagnosis of DLBCL in 17 samples (46%), Burkitt`s lymphoma (BL) in 1 sample (2.7%), FL grade I in 7 samples (19%), FL grade II in 7 samples (19%), and 5 samples were FL that were not graded. All the FL specimens as well as the BL specimen showed diploid DNA content (DNA Index=1). DNA aneuploidy was detected in 11 (64.7%) (1 hypodiploid and 10 hyperdiploid) DLBCL specimens (mean DNA index=1.25±0.3). The remaining 6 DLBCL specimens and the BL specimen with the diploid DNA content showed significantly higher S-phase fraction compared with FL (3.73±2.75, 15.54±10.16, and 33.3 % S-phase in FL , DLBCL and BL respectively, pConclusions: These preliminary results confirmed previous observations demonstrating higher incidences of aneuploidy in aggressive NHLs (1). We suggest that including DNA analysis in the routine lymphoma diagnostic panel could be helpful for differentiating CD10+ DLBCL from FL.