Analysis of Diffuse Large B-cell Lymphoma using Immunohistochemical Algorithm: A Cross-sectional Study

Abstract

Introduction: Diffuse Large B-cell Lymphoma (DLBCL) is the most common Non-Hodgkin’s Lymphoma (NHL). Using Gene Expression Profiling (GEP) DLBCL has been subtyped into two groups of prognostic importance, Germinal Center B-cell (GCB) like and activated B-cell like. GCB DLBCL has a better survival and can be identified using Hans algorithm with three immunohistochemical markers Cluster Differentiation (CD10), B-cell lymphoma 6 (BCL6) and Multiple Myeloma Oncogene-1 (MUM1). Aim: To analyse DLBCL using Hans algorithm as both GCB lymphoma and non GCB lymphoma have different treatment and prognosis. Materials and Methods: This was a cross-sectional study conducted in the Department of Pathology, Government Medical College, Kozhikode, Kerala, India, from January 2019 to December 2020. A total of 97 DLBCL cases received in the Department of Pathology, from January 2016 to December 2019 were included in the study were subtyped using Hans algorithm. CD10, BCL6 and MUM1 were considered positive, if more than 30% of the tumour cells showed staining by the respective antibodies. The relation between DLBCL subtypes and the age, gender, symptoms, site of initial involvement, organomegaly, Ann Arbor stage, treatment response and overall survival. Findings in the patients were analysed using Chi-square test. Statistical Package for Social Sciences (SPSS) software version 18.0. Overall survival was estimated using Kaplan-Meier method. Results: The median age of study population was 60 years (age range: 31-85 years) and there were 55 (56.7%) males and 42 (43.3%) females. Out of the 97 DLBCL cases 47 (48.5%) were GCB and 50 (51.5%) were non GCB subtype. Statistical analysis was done only in 88 patients (excluded nine recurrent lymphoma patients, which may have a different outcome). There was significant association (p-value=0.003) between stage and subtypes as majority of the non GCB cases presented in an advanced stage. The rate of complete remission with Rituximab Cyclophosphamid Hydroxydaunorubicin Oncovin Prednisone (RCHOP) chemotherapy was higher in GCB (58.75%) compared to non GCB (15.25%) subtypes (p-value=0.001). Overall survival rate of GCB was 74.4% and non GCB was 31% with a p-value of 0.001. There was no statistically significant relation between DLBCL subtypes and other clinicopathological factors. Conclusion: In the present study, the patients within the GCB subtype had better treatment response and overall survival rate compared to non GCB subtype. Non germinal center subtype presented in advanced stage and had a worse prognosis. Therefore, it is essential to subtype DLBCL in all cases to identify non GCB subtype, which may need additional treatment after RCHOP chemotherapy.