Does EBV Cause DLBCL?
EBV does not cause most cases of DLBCL, but it is directly implicated in a specific subset representing approximately 8-10% of all DLBCL cases, now recognized as a distinct entity called EBV-positive DLBCL, NOS (not otherwise specified). 1, 2
Understanding the EBV-DLBCL Relationship
EBV as a Causative Agent in a Subset of Cases
EBV is present in approximately 10% of all DLBCL cases, with the virus playing a direct pathogenic role in lymphomagenesis through expression of viral oncoproteins and modulation of host cell signaling pathways. 3
The virus is classified as a Group I carcinogen by the WHO and provides survival factors to EBV-positive DLBCL cells, demonstrating that it is not merely a bystander but an active driver of malignancy in these cases. 4, 5
EBV-positive DLBCL has distinct biology related to both viral and host factors, including enhanced NFκB activity, which distinguishes it from EBV-negative DLBCL. 3
Clinical Context and Risk Factors
The highest incidence occurs in immunocompromised patients and the elderly, where immunosenescence allows EBV to proliferate in an unregulated fashion and express viral antigens that predispose to transformation. 3, 6
EBV-positive DLBCL of the elderly is more common in Asian countries (8-10% of DLBCLs) compared to Western populations, suggesting geographic and possibly genetic susceptibility factors. 5
Iatrogenic immunosuppression (both transplant and non-transplant settings, including patients on immunomodulators like tacrolimus) can predispose to EBV-driven lymphoproliferative disorders. 6, 7
Diagnostic Recognition
Establishing EBV Positivity
EBER (EBV-encoded RNA) staining is the standard diagnostic method and should be included in the immunohistochemical panel for DLBCL evaluation. 1
The ICC 2022 specifies that >80% of malignant cells must express EBER for diagnosis of EBV-positive DLBCL, NOS, while WHO-HAEM5 emphasizes that the majority of tumor cells should be EBER positive without a defined threshold. 2
EBV-positive DLBCL, NOS was included as a provisional entity in the 2016 WHO classification and has been further refined as an established entity in the WHO fifth edition and ICC 2022 classifications. 4, 2
Important Diagnostic Pitfalls
Not all EBV-positive B-cell lymphomas are DLBCL - the differential diagnosis includes plasmablastic lymphoma, DLBCL associated with chronic inflammation, primary effusion lymphoma, and post-transplant lymphoproliferative disorders. 2, 8
EBV-positive mucocutaneous ulcer (EBVMCU), EBV-positive polymorphic LPD, and EBV-positive classic Hodgkin lymphoma can have significant diagnostic overlap and must be distinguished from EBV-positive DLBCL. 8
Clinical Implications
Prognostic Considerations
EBER positivity is significantly associated with worse overall survival and should be factored into risk stratification. 9
EBV-positive DLBCL might have a worse prognosis than EBV-negative DLBCL in the era of chemoimmunotherapy, though outcomes have improved compared to historical data. 2
The Oyama score (age >70 years and presence of B symptoms) can be used for risk stratification specifically in EBV-positive DLBCL. 2
Treatment Implications
Patients with EBV-positive DLBCL, NOS should be staged and managed following similar guidelines as EBV-negative DLBCL, but inclusion in clinical trials is recommended when available due to potentially worse outcomes. 2
There is opportunity for targeted therapy including immunotherapy and adoptive T-cell therapies, which have shown encouraging results in EBV-associated lymphoproliferative diseases. 6
Expression of CD30 and PD-1/PD-L1 are emerging as potential adverse but targetable biomarkers in EBV-positive DLBCL. 2
The Bottom Line
EBV is not a general cause of DLBCL but is the causative agent in a specific, clinically distinct subset representing about 10% of cases, particularly in elderly and immunocompromised patients. The remaining 90% of DLBCL cases are EBV-negative and arise through different pathogenic mechanisms. 3, 6