Clinicopathological features of primary central nervous system diffuse large B cell lymphoma: Experience from a Tertiary Center in North India

Background: Primary central nervous system-diffuse large B-cell lymphoma (PCNS-DLBCL) is a rare extranodal Non-Hodgkin lymphoma. There is relative paucity of literature on PCNSL from Indian subcontinent. We aimed to analyze the clinicopathological features of PCNSL and categorize them into germinal center B cell (GCB) and non-GCB subtypes to assess their prognostic significance in Indian context. Methods: All patients with histopathologically diagnosed PCNSLs at our center over a period of 6 years were recruited and classified into GCB and non-GCB using Han’s algorithm (immunohistochemistry for CD10, BCL6 and MUM1). In situ hybridization (ISH) for Epstein-Barr virus (EBV)-encoded RNA was performed. Results: Eighty-six cases of PCNS-DLBCL were included with median age of 55 years. Majority of them were supratentorial in location (n = 62). All patients were immunocompetent. On immunohistochemical assessment, 69 (80.2%) were of NGCB subtype, 10 (11.6%) were of GCB subtype, and 7 (8.1%) were unclassified. Overall, MUM1, BCL-6, and CD10 expressions were seen in 69 (80.2%), 28 (32.6%), and 2 cases (2.3%), respectively. Four cases (4.6%) showed C-MYC expression. The median overall survival (OS) was 675 days. None of the factors (age, sex, location, immunomarkers, and GCB vs. NGCB phenotype) showed correlation with OS; however, BCL6 positive cases showed slight better OS (P > 0.05). All cases were negative for EBV-LMP1 on ISH. Conclusion: The majority of the CNS DLBCL belongs to non-GCB phenotype and uniformly carry poor prognosis, irrespective of their phenotype. Individual markers, such as BCL-6, MUM1, or CD10, are unable to predict outcome in PCNS-DLBCL.