Comparative analysis of immunohistochemical features of nodal versus extranodal diffuse large B cell lymphoma with respect to cell-of-origin classification

ABSTRACT

Background: Diffuse large B-cell lymphoma (DLBCL) represents a heterogeneous group of lymphoid malignancies with distinct oncogenic events and clinical behavior that cannot be unraveled by morphology and immunophenotype alone. Simple biological segregation such as the Hans classifier helps to explain the heterogeneous responses to standard treatment and provides a rationale for the investigation of novel targeted therapies. Aims and Objectives: In this study, we tried to estimate immunohistochemical (IHC) features of nodal and extranodal DLBCL using cell-of-origin classification (Hans Algorithm) with the markers CD10, Bcl-6, MUM1. Materials and Methods: Blocks of the patients with a histological diagnosis of DLBCL over the past 3 years were retrieved and submitted for IHC analysis to classify into germinal center B cell type (GCB) and non-GCB type. Results: Mean age for nodal DLBL was 48.19 � 14.68 years, extranodal were 55.7 � 13.22 years. Mean age for GCB were 56.6 � 15.66 years whereas for non-GCB were 51.45 � 12.85 years. Among nodal lymphomas cervical was the most common site and among extranodal lymphomas, intestinal lymphomas were commonest (including colorectal). Relative proportion of GCB among extranodal was 28.78%, whereas in nodal DLBCL it was 16.67%, relative risk of getting GCB type DLBCL was 1.72 times higher in extranodal compared to nodal DLBCL (P = 0.081). Total positivity of MUM1 was 17%, whereas for Bcl6 and CD10 it was 29% and 15% respectively. Ki67 was considerably higher in GCB type and for extranodal DLBCL in our study. Conclusion: Proportion of extranodal GCB type DLBCL compared to nodal DLBCL is considerably higher in our study population, though it varies greatly among Asian and world data. Uniform meta-analysis and systematic review is necessary to stratify.