EBV-positive diffuse large B-cell lymphoma, not otherwise specified: 2020 update on diagnosis, risk-stratification and management

Hijacking and rewiring of host CircRNA/miRNA/mRNA competitive endogenous RNA (ceRNA) regulatory networks by oncoviruses during development of viral cancers

A significant portion of human cancers are caused by oncoviruses (12%-25%). Oncoviruses employ various strategies to promote their replication and induce tumourigenesis in host cells, one of which involves modifying the gene expression patterns of the host cells, leading to the rewiring of genes and resulting in significant changes in cellular processes and signalling pathways. In recent studies, a specific mode of gene regulation known as circular RNA (circRNA)-mediated competing endogenous RNA (ceRNA) networks has emerged as a key player in this context. CircRNAs, a class of non-coding RNA molecules, can interact with other RNA molecules, such as mRNAs and microRNAs (miRNAs), through a process known as ceRNA crosstalk. This interaction occurs when circRNAs, acting as sponges, sequester miRNAs, thereby preventing them from binding to their target mRNAs and modulating their expression. By rewiring the host cell genome, oncoviruses have the ability to manipulate the expression and activity of circRNAs, thereby influencing the ceRNA networks that can profoundly impact cellular processes such as cell proliferation, differentiation, apoptosis, and immune responses. This review focuses on a comprehensive evaluation of the latest findings on the involvement of virus-induced reprogramming of host circRNA-mediated ceRNA networks in the development and pathophysiology of human viral cancers, including cervical cancer, gastric cancer, nasopharyngeal carcinoma, Kaposi's sarcoma, hepatocellular carcinoma, and diffuse large B cell lymphoma. Understanding these mechanisms can improve our knowledge of how oncoviruses contribute to human tumourigenesis and identify potential targets for developing optimised therapies and diagnostic tools for viral cancers.

Comparison of genomic alterations in Epstein-Barr virus-positive and Epstein-Barr virus-negative diffuse large B-cell lymphoma

BACKGROUND

Epstein-Barr virus (EBV)-positive diffuse large B-cell lymphoma (EBV-posDLBCL) is an aggressive B-cell lymphoma that often presents similar morphological and immune phenotype features to that of EBV-negative DLBCL (EBV-negDLBCL).

AIMS AND METHODS

To better understand their difference in genomic landscape, we performed whole-exome sequencing (WES) of EBV-posDLBCL and EBV-negDLBCL.

RESULTS

This analysis revealed a new mutational signature 17 (unknown) and signature 29 (smoking) in EBV-posDLBCL as well as a specific mutational signature 24 (associated with aflatoxin) in EBV-negDLBCL. Compared with EBV-negDLBCL, more somatic copy number alterations (CNAs) and deletions were detected in EBV-posDLBCL (p = 0.01). The most frequent CNAs specifically detected in EBV-posDLBCL were gains at 9p24.1 (PDL1 and JAK2), 8q22.2-q24.23 (DEPTOR and MYC), and 7q31.31-q32.2 (MET), which were validated in additional EBV-posDLBCL cases. Overall, 53.7% (22/41) and 62.9% (22/35) of the cases expressed PD-L1 and c-MET, respectively, in neoplastic cells, whereas only 15.4% (4/26) expressed c-MYC. Neoplastic c-MET expression was positively correlated with PD-L1 (p < 0.001) and MYC expression (p = 0.016). However, EBV-posDLBCL cases did not show any differences in overall survival between PD-L1-, c-MET-, or c-MYC-positive and -negative cases or between age-related groups. Analysis of the association between somatic mutation load and EBV status showed no difference in the distribution of tumor mutant burden between the two lymphomas (p = 0.41). Recurrent mutations in EBV-posDLBCL implicated several genes, including DCAF8L1, KLF2, and NOL9, while in EBV-negDLBCL, ANK2, BPTF, and CNIH3 were more frequently mutated. Additionally, PIM1 is the most altered gene in all the WES-detected cases.

CONCLUSIONS

Our results confirm that genomic alteration differs significantly between EBV-posDLBCL and EBV-negDLBCL, and reveal new genetic alterations in EBV-posDLBCL. The positive correlation of c-MET and PD-L1/c-Myc expression may be involved in the pathogenesis of EBV-posDLBCL, which is should be explored prospectively in trials involving MET-directed therapies.

Epstein-Barr virus-encoded EBNA2 downregulates ICOSL by inducing miR-24 in B-cell lymphoma

ABSTRACT

Hematological malignancies such as Burkitt lymphoma (BL), Hodgkin lymphoma (HL), and diffuse large B-cell lymphoma (DLBCL) cause significant morbidity in humans. A substantial number of these lymphomas, particularly HL and DLBCLs have poorer prognosis because of their association with Epstein-Barr virus (EBV). Our earlier studies have shown that EBV-encoded nuclear antigen (EBNA2) upregulates programmed cell death ligand 1 in DLBCL and BLs by downregulating microRNA-34a. Here, we investigated whether EBNA2 affects the inducible costimulator (ICOS) ligand (ICOSL), a molecule required for efficient recognition of tumor cells by T cells through the engagement of ICOS on the latter. In virus-infected and EBNA2-transfected B-lymphoma cells, ICOSL expression was reduced. Our investigation of the molecular mechanisms revealed that this was due to an increase in microRNA-24 (miR-24) by EBNA2. By using ICOSL 3' untranslated region-luciferase reporter system, we validated that ICOSL is an authentic miR-24 target. Transfection of anti-miR-24 molecules in EBNA2-expressing lymphoma cells reconstituted ICOSL expression and increased tumor immunogenicity in mixed lymphocyte reactions. Because miR-24 is known to target c-MYC, an oncoprotein positively regulated by EBNA2, we analyzed its expression in anti-miR-24 transfected lymphoma cells. Indeed, the reduction of miR-24 in EBNA2-expressing DLBCL further elevated c-MYC and increased apoptosis. Consistent with the in vitro data, EBNA2-positive DLBCL biopsies expressed low ICOSL and high miR-24. We suggest that EBV evades host immune responses through EBNA2 by inducing miR-24 to reduce ICOSL expression, and for simultaneous rheostatic maintenance of proproliferative c-MYC levels. Overall, these data identify miR-24 as a potential therapeutically relevant target in EBV-associated lymphomas.

The progress of novel strategies on immune-based therapy in relapsed or refractory diffuse large B-cell lymphoma

Diffuse large B-cell lymphoma (DLBCL) can be cured with standard front-line immunochemotherapy, whereas nearly 30-40% of patients experience refractory or relapse. For several decades, the standard treatment strategy for fit relapsed/refractory (R/R) DLBCL patients has been high-dose chemotherapy followed by autologous hematopoietic stem cell transplant (auto-SCT). However, the patients who failed in salvage treatment or those ineligible for subsequent auto-SCT have dismal outcomes. Several immune-based therapies have been developed, including monoclonal antibodies, antibody-drug conjugates, bispecific T-cell engaging antibodies, chimeric antigen receptor T-cells, immune checkpoint inhibitors, and novel small molecules. Meanwhile, allogeneic SCT and radiotherapy are still necessary for disease control for fit patients with certain conditions. In this review, to expand clinical treatment options, we summarize the recent progress of immune-related therapies and prospect the future indirections in patients with R/R DLBCL.

A New Face of Fibrin-Associated Large B-Cell Lymphoma: Epstein-Barr Virus-Positive Breast Implant-Associated Diffuse Large B-Cell Lymphoma

Recently, there have been reports of what could be a new lymphoproliferative entity: breast implant-associated Epstein-Barr virus positive (EBV+) diffuse large B-cell lymphoma (EBV+ BIA-DLBCL). The new World Health Organization classification has categorized it as fibrin-associated large B-cell lymphomas (FA-LBCLs); therefore, it could be referred to as breast implant-associated fibrin-associated large B-cell lymphomas (BIA-FA-LBCLs). Although the association between breast implants and lymphomas has been known since the mid-1990s, it has been almost exclusively breast implant-associated anaplastic large cell lymphoma (BIA-ALCL). Here, we describe the first case of BIA-FA-LBCL at our center, with a literature review of the clinical features, diagnosis and treatment approach of this lymphoma. We also explore the differential diagnosis of BIA-FA-LBCL, highlighting the diagnostic challenges and the reasons that have led these lymphomas to being labeled as a new face of FA-LBCL.

EBV and Lymphomagenesis

The clinical significance of Epstein–Barr virus (EBV) cannot be understated. Not only does it infect approximately 90% of the world’s population, but it is also associated with numerous pathologies. Diseases linked to this virus include hematologic malignancies such as diffuse large B-cell lymphoma, Hodgkin lymphoma, Burkitt lymphoma, primary CNS lymphoma, and NK/T-cell lymphoma, epithelial malignancies such as nasopharyngeal carcinoma and gastric cancer, autoimmune diseases such as multiple sclerosis, Graves’ disease, and lupus. While treatment for these disease states is ever evolving, much work remains to more fully elucidate the relationship between EBV, its associated disease states, and their treatments. This paper begins with an overview of EBV latency and latency-associated proteins. It will then review EBV’s contributions to select hematologic malignancies with a focus on the contribution of latent proteins as well as their associated management.

Potential Pathogenic Impact of Cow’s Milk Consumption and Bovine Milk-Derived Exosomal MicroRNAs in Diffuse Large B-Cell Lymphoma

Epidemiological evidence supports an association between cow’s milk consumption and the risk of diffuse large B-cell lymphoma (DLBCL), the most common non-Hodgkin lymphoma worldwide. This narrative review intends to elucidate the potential impact of milk-related agents, predominantly milk-derived exosomes (MDEs) and their microRNAs (miRs) in lymphomagenesis. Upregulation of PI3K-AKT-mTORC1 signaling is a common feature of DLBCL. Increased expression of B cell lymphoma 6 (BCL6) and suppression of B lymphocyte-induced maturation protein 1 (BLIMP1)/PR domain-containing protein 1 (PRDM1) are crucial pathological deviations in DLBCL. Translational evidence indicates that during the breastfeeding period, human MDE miRs support B cell proliferation via epigenetic upregulation of BCL6 (via miR-148a-3p-mediated suppression of DNA methyltransferase 1 (DNMT1) and miR-155-5p/miR-29b-5p-mediated suppression of activation-induced cytidine deaminase (AICDA) and suppression of BLIMP1 (via MDE let-7-5p/miR-125b-5p-targeting of PRDM1). After weaning with the physiological termination of MDE miR signaling, the infant’s BCL6 expression and B cell proliferation declines, whereas BLIMP1-mediated B cell maturation for adequate own antibody production rises. Because human and bovine MDE miRs share identical nucleotide sequences, the consumption of pasteurized cow’s milk in adults with the continued transfer of bioactive bovine MDE miRs may de-differentiate B cells back to the neonatal “proliferation-dominated” B cell phenotype maintaining an increased BLC6/BLIMP1 ratio. Persistent milk-induced epigenetic dysregulation of BCL6 and BLIMP1 expression may thus represent a novel driving mechanism in B cell lymphomagenesis. Bovine MDEs and their miR cargo have to be considered potential pathogens that should be removed from the human food chain.

Epstein-Barr Virus and the Pathogenesis of Diffuse Large B-Cell Lymphoma

Epstein-Barr virus (EBV), defined as a group I carcinogen by the World Health Organization (WHO), is present in the tumour cells of patients with different forms of B-cell lymphoma, including Burkitt lymphoma, Hodgkin lymphoma, post-transplant lymphoproliferative disorders, and, most recently, diffuse large B-cell lymphoma (DLBCL). Understanding how EBV contributes to the development of these different types of B-cell lymphoma has not only provided fundamental insights into the underlying mechanisms of viral oncogenesis, but has also highlighted potential new therapeutic opportunities. In this review, we describe the effects of EBV infection in normal B-cells and we address the germinal centre model of infection and how this can lead to lymphoma in some instances. We then explore the recent reclassification of EBV+ DLBCL as an established entity in the WHO fifth edition and ICC 2022 classifications, emphasising the unique nature of this entity. To that end, we also explore the unique genetic background of this entity and briefly discuss the potential role of the tumour microenvironment in lymphomagenesis and disease progression. Despite the recent progress in elucidating the mechanisms of this malignancy, much work remains to be done to improve patient stratification, treatment strategies, and outcomes.

High plasma EBV-DNA load and positive EBER status associated with viral recurrence and persistent infection in early treatment of lymphoma

The relationship between plasma EBV-DNA load (PEDL) and Epstein-Barr virus (EBV)-encoded small RNA (EBER) during the early treatment of lymphoma remains unclear. We explored discrepancies in PEDL and variables associated with EBER and evaluated the consistency between EBER and qualitative analysis of PEDL (qPEDL). Serial measurements of PEDL were performed to determine the dynamic changes of PEDL in early treatment of lymphoma. As a result, the median PEDL of non-Hodgkin's lymphoma NKT cell subtype (NHL-NKT) was higher than that of non-Hodgkin's lymphoma B cell subtype (NHL-B), the median PEDL of extranodal NK/T cell lymphoma (ENKTCL) was higher than that of diffuse large B cell lymphoma (DLBCL), and the median PEDL of EBER positive was higher than that of EBER negative. Age, Ki-67 ≧ 80%, Bcl-2 ≧ 80%, p53, and qPEDL were related to EBER. The PEDL could distinguish NHL-B, DLBCL, NHL-NKT, and ENKTCL from other lymphoma subtypes. EBER-positive patients spent more time with viral "turn negative (TN)" and "continuous positive (CP)" and less time with viral "continuous negative (CN)." The median PEDL of CP was higher than that of TN. In conclusion, although EBER affects the levels of PEDL in general, it has poor concordance with qPEDL. Our results show, for the first time, that high PEDL and positive EBER present a strong association with viral recurrence and persistent infection in the early treatment of lymphoma.

Viral Agents as Potential Drivers of Diffuse Large B-Cell Lymphoma Tumorigenesis

Among numerous causative agents recognized as oncogenic drivers, 13% of total cancer cases occur as a result of viral infections. The intricacy and diversity of carcinogenic processes, however, raise significant concerns about the mechanistic function of viruses in cancer. All tumor-associated viruses have been shown to encode viral oncogenes with a potential for cell transformation and the development of malignancies, including diffuse large B-cell lymphoma (DLBCL). Given the difficulties in identifying single mechanistic explanations, it is necessary to combine ideas from systems biology and viral evolution to comprehend the processes driving viral cancer. The potential for more efficient and acceptable therapies lies in targeted medicines that aim at viral proteins or trigger immune responses to either avoid infection or eliminate infected or cancerous cells. In this review, we aim to describe the role of viral infections and their mechanistic approaches in DLBCL tumorigenesis. To the best of our knowledge, this is the first review summarizing the oncogenic potential of numerous viral agents in DLBCL development.

An integrated prognostic model for diffuse large B‐cell lymphoma treated with immunochemotherapy

Diffuse large B‐cell lymphoma (DLBCL), the most frequent non‐Hodgkin's lymphoma subtype, is characterized by strong biological, morphological, and clinical heterogeneity, but patients are treated with immunochemotherapy in a relatively homogeneous way. Here, we have used a customized NanoString platform to analyze a series of 197 homogeneously treated DLBCL cases. The platform includes the most relevant genes or signatures known to be useful for predicting response to R‐CHOP (Rituximab, Cyclophosphamide, Doxorubicin, Vincristine, and Prednisone) in DLBCL cases. We generated a risk score that combines the International Prognostic Index with cell of origin and double expression of MYC/BCL2, and stratified the series into three groups, yielding hazard ratios from 0.15 to 5.49 for overall survival, and from 0.17 to 5.04 for progression‐free survival. Group differences were highly significant (p < 0.0001), and the scoring system was applicable to younger patients (<60 years of age) and patients with advanced or localized stages of the disease. Results were validated in an independent dataset from 166 DLBCL patients treated in two distinct clinical trials. This risk score combines clinical and biological data in a model that can be used to integrate biological variables into the prognostic models for DLBCL cases.

CD30+ Lymphoproliferative Disorders as Potential Candidates for CD30-Targeted Therapies

CONTEXT.—

In the early 1980s, a monoclonal antibody termed Ki-1 was developed against a cell line derived from a patient with Hodgkin lymphoma. This antibody detected a limited number of benign activated lymphocytes in lymphoid tissue, whereas in Hodgkin lymphoma it appeared to be nearly specific for Reed-Sternberg cells and their mononuclear variants. Subsequent studies showed that Ki-1 expression defined a new type of lymphoma that was later designated anaplastic large cell lymphoma with or without anaplastic large cell kinase expression/translocation. In the past 30 years, numerous new lymphoma entities have been defined, many of which are variably positive for CD30. Many virally transformed lymphoproliferative disorders are also frequently positive for CD30.

OBJECTIVE.—

To illustrate the broad spectrum of CD30+ hematologic malignancies and to provide an update of CD30-targeted therapies.

DATA SOURCES.—

Personal experiences and published works in PubMed.

CONCLUSIONS.—

Because of its low expression in normal tissue, CD30 was studied as a therapeutic target for many years. However, the first functional humanized antibody against CD30 was developed only about 10 years ago. Brentuximab vedotin is a humanized anti-CD30 antibody linked to a cytotoxin, and was approved by the US Food and Drug Administration in 2012 for treating refractory Hodgkin lymphoma and anaplastic large cell lymphoma. Since then, the list of Food and Drug Administration-approved CD30-targeted hematologic malignancies has grown. Recently, the therapies using tumor antigen-specific chimeric antigen receptor T cells targeting CD30 have incited a great deal of enthusiasm and are studied in clinical trials.

Epstein Barr virus-positive B-cell lymphoma is highly vulnerable to MDM2 inhibitors in vivo

MDM2 inhibitors have potent in vivo activity against and could be a novel therapy for EBV-positive B-cell lymphoma.

EBV positivity or loss of BCL6 expression can be a potential predictive biomarker for response to MDM2 inhibitors in patients with lymphoma

Epstein-Barr virus–positive (EBV-positive) B-cell lymphomas are common in immunocompromised patients and remain an unmet medical need. Here we report that MDM2 inhibitors (MDM2is) navtemadlin and idasanutlin have potent in vivo activity in EBV-positive B-cell lymphoma established in immunocompromised mice. Tumor regression was observed in all 5 EBV-positive xenograft–associated B-cell lymphomas treated with navtemadlin or idasanutlin. Molecular characterization showed that treatment with MDM2is resulted in activation of p53 pathways and downregulation of cell cycle effectors in human lymphoma cell lines that were either EBV-positive or had undetectable expression of BCL6, a transcriptional inhibitor of the TP53 gene. Moreover, treatment with navtemadlin resulted in tumor regression and prevented systemic dissemination of EBV-positive lymphoma derived from 2 juvenile patients with posttransplant lymphoproliferative diseases, including 1 whose tumor was resistant to virus-specific T-cell therapy. These results provide proof-of-concept for targeted therapy of EBV-positive lymphoma with MDM2is and the feasibility of using EBV infection or loss of BCL6 expression to identify responders to MDM2is.

CircEAF2 counteracts Epstein-Barr virus-positive diffuse large B-cell lymphoma progression via miR-BART19-3p/APC/β-catenin axis

Background

Epstein-Barr virus (EBV) represents an important pathogenic factor of lymphoma and is significantly associated with poor clinical outcome of diffuse large B-cell lymphoma (DLBCL). Circular RNAs (circRNAs) play an essential role in lymphoma progression. However, the underlying mechanism of circRNA on DLBCL progression related to EBV remains largely unknown.

Methods

CircRNA was screened by high-throughput sequencing in tumor samples of 12 patients with DLBCL according to EBV infection status. Expression of circEAF2, as well as the relationship with clinical characteristics and prognosis, were further analyzed in tumor samples of 100 DLBCL patients using quantitative real-time PCR. Gain- and loss-of-function experiments were conducted to investigate the biological functions of circEAF2 both in vitro and in vivo. The underlying mechanism of circRNA on DLBCL progression were further determined by RNA sequencing, RNA pull down assay, dual-luciferase reporter assay, rescue experiments and western blotting.

Results

We identified a novel circRNA circEAF2, which was downregulated in EBV + DLBCL and negatively correlated with EBV infection and DLBCL progression. In EBV-positive B lymphoma cells, circEAF2 overexpression induced lymphoma cell apoptosis and sensitized lymphoma cells to epirubicin. As mechanism of action, circEAF2 specifically targeted EBV-encoded miR-BART19-3p, upregulated APC, and suppressed downstream β-catenin expression, resulting in inactivation of Wnt signaling pathway and inhibition of EBV + DLBCL cell proliferation. In EBV-positive B-lymphoma murine models, xenografted tumors with circEAF2 overexpression presented decreased Ki-67 positivity, increased cell apoptosis and retarded tumor growth.

Conclusions

CircEAF2 counteracted EBV + DLBCL progression via miR-BART19-3p/APC/β-catenin axis, referring circEAF2 as a potential prognostic biomarker. Therapeutic targeting EBV-encoded miRNA may be a promising strategy in treating EBV-associated lymphoid malignancies.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12943-021-01458-9.

Onset of pulmonary Epstein-Barr virus-positive diffuse large B-cell lymphoma in a patient with silicosis

How Epstein-Barr virus (EBV)-positive diffuse large B-cell lymphoma (DLBCL) occasionally occurs following chronic inflammation remains to be elucidated. The case of a 57-year-old man who developed pulmonary EBV-positive DLBCL from underlying silicosis lesions is presented. Immunohistochemical examination of the resected silicosis lesions showed predominant helper T cells and M1/M2 macrophages, with a lack of B cells, regulatory T cells, and resident memory T cells. Two years later, EBV-positive DLBCL emerged unexpectedly from the silicosis. The imbalance of the immune cells in the microenvironment, at least in part, may help explain how chronic inflammation contributes to EBV-positive DLBCL.

Epstein-Barr Virus-Associated Malignancies and Immune Escape: The Role of the Tumor Microenvironment and Tumor Cell Evasion Strategies

Simple Summary

The Epstein–Barr virus, also termed human herpes virus 4, is a human pathogenic double-stranded DNA virus. It is highly prevalent and has been linked to the development of 1–2% of cancers worldwide. EBV-associated malignancies encompass various structural and epigenetic alterations. In addition, EBV-encoded gene products and microRNAs interfere with innate and adaptive immunity and modulate the tumor microenvironment. This review provides an overview of the characteristic features of EBV with a focus on the intrinsic and extrinsic immune evasion strategies, which contribute to EBV-associated malignancies.

Abstract

The detailed mechanisms of Epstein–Barr virus (EBV) infection in the initiation and progression of EBV-associated malignancies are not yet completely understood. During the last years, new insights into the mechanisms of malignant transformation of EBV-infected cells including somatic mutations and epigenetic modifications, their impact on the microenvironment and resulting unique immune signatures related to immune system functional status and immune escape strategies have been reported. In this context, there exists increasing evidence that EBV-infected tumor cells can influence the tumor microenvironment to their own benefit by establishing an immune-suppressive surrounding. The identified mechanisms include EBV gene integration and latent expression of EBV-infection-triggered cytokines by tumor and/or bystander cells, e.g., cancer-associated fibroblasts with effects on the composition and spatial distribution of the immune cell subpopulations next to the infected cells, stroma constituents and extracellular vesicles. This review summarizes (i) the typical stages of the viral life cycle and EBV-associated transformation, (ii) strategies to detect EBV genome and activity and to differentiate various latency types, (iii) the role of the tumor microenvironment in EBV-associated malignancies, (iv) the different immune escape mechanisms and (v) their clinical relevance. This gained information will enhance the development of therapies against EBV-mediated diseases to improve patient outcome.

Advances in the Pathogenesis of EBV-Associated Diffuse Large B Cell Lymphoma

Diffuse large B-cell lymphoma (DLBCL) is the most common non-Hodgkin's lymphoma (NHL) in adults. Epstein-Barr virus (EBV) positive DLBCL of the elderly was defined by the World Health Organization (WHO) in 2008, it was restricted only to patients older than 50 years old, and it was attributed to immunesenescence associated with physiological aging. After the description of EBV-associated DLBCL in children and young adults, the WHO redefined the definition, leading to the substitution of the modifier "elderly" with "not otherwise specified" (EBV + DLBCL, NOS) in the updated classification, and it is no more considered provisional. The incidence of EBV + DLBCL, NOS varies around the world, in particular influenced by the percentage of EBV+ cells used as cut-off to define a case as EBV-associated. EBV has effect on the genetic composition of tumor cells, on survival, and at the recruitment of immune cells at the microenvironment. In this review, the role of EBV in the pathogenesis of DLBCL is discussed.

Diffuse Large B-Cell Lymphoma: Recognition of Markers for Targeted Therapy

Diffuse large B-cell lymphomas (DLBCL)s, the most common type of Non-Hodgkin’s Lymphoma, constitute a heterogeneous group of disorders including different disease sites, strikingly diverse molecular features and a profound variability in the clinical behavior. Molecular studies and clinical trials have partially revealed the underlying causes for this variability and have made possible the recognition of some molecular variants susceptible of specific therapeutic approaches. The main histogenetic groups include the germinal center, activated B cells, thymic B cells and terminally differentiated B cells, a basic scheme where the large majority of DLBCL cases can be ascribed. The nodal/extranodal origin, specific mutational changes and microenvironment peculiarities provide additional layers of complexity. Here, we summarize the status of the knowledge and make some specific proposals for addressing the future development of targeted therapy for DLBC cases.

Primary age-related EBV-associated effusion-based lymphoma successfully treated with rituximab and thoracentesis

EBV-positive HHV8-negative EBL is part of the spectrum of EBV-positive diffuse large B-cell lymphoma NOS. This entity can be labeled as primary age-related EBV-associated EBL and appears to respond well to rituximab and thoracentesis.

The Incidence of Epstein-Barr Virus-Positive Diffuse Large B-Cell Lymphoma: A Systematic Review and Meta-Analysis

Simple Summary

The worldwide prevalence of Epstein-Barr virus-positive (EBV+) diffuse large B-cell lymphoma (DLBCL) is undetermined. There is no clearly defined cut-off for EBV-encoded RNA (EBER) positivity in tumor cells by in situ hybridization. A lack of common criteria for positive expression of EBER has been raised as a limitation for interpreting and understanding the geographic and ethnic disparity of prevalence of EBV+ DLBCL. We conducted a systematic literature review and meta-analysis to establish the proportions of EBV+ DLBCL patients. Results showed that the pooled proportion of EBER positivity was 7.9% in patients with de novo DLBCL. The prevalence of EBV+ DLBCL was significantly higher in Asia and South America compared with Western countries. A tendency for lower pooled proportions was observed in studies using a higher cut-off for EBER positivity. The patients’ age did not significantly affect the prevalence. These findings may improve our current knowledge of the EBV+ DLBCL.

Abstract

The worldwide prevalence of Epstein-Barr virus-positive (EBV+) diffuse large B-cell lymphoma (DLBCL) is undetermined. There is no clearly defined cut-off for EBV-encoded RNA (EBER) positivity in tumor cells by in-situ hybridization. The purpose of this study was to establish the proportions of EBV+ DLBCL patients and influence of the different cut-offs for EBER positivity, geographical location, and age on the prevalence of EBV+ DLBCL. PubMed and EMBASE were searched for studies published up to May 28, 2020 that reported proportions of EBER positivity in immunocompetent and de novo DLBCL patients. The pooled proportions were computed by an inverse variance method for calculating the weights and the DerSimonian–Laird method. Multiple subgroup analyses were conducted to explore any heterogeneity. Thirty-one studies (8249 patients) were included. The pooled proportion of EBV+ DLBCL was 7.9% (95% CI, 6.2–10.0%) with significant heterogeneity among studies (p < 0.001). The prevalence of EBV+ DLBCL was significantly higher in Asia and South America compared with Western countries (p < 0.01). The cut-offs for EBER positivity (10%, 20%, 50%) and patients’ age (≥50 years vs. <50 years) did not significantly affect the prevalence (p ≥ 0.10). EBV+ DLBCL is rare with a pooled proportion of 7.9% in patients with DLBCL and the geographic heterogeneity was confirmed.

Primary Diffuse Large B-Cell Lymphoma of the Female Urethra: A Case Report and Review of the Literature

Primary urethral non-Hodgkin's lymphoma (NHL) is uncommon. This case study reports the case of a 52-year-old woman with a light red mass at the urethral orifice. Her clinical manifestations included frequent urination, urgency, dysuria, and occasionally blood in urine. The tumor was surgically removed, and the pathological and immunohistochemistry examination confirmed the presence of a diffuse large B-cell lymphoma (DLBCL). Examination using positron emission tomography/computed tomography (PET/CT) revealed multiple hypermetabolic lymph nodes next to the external iliac vessels and bilateral inguinal regions, and focal hypermetabolic lesions in the vulvar nodules (consistent with the changes caused by lymphoma infiltration). Eight cycles of chemotherapy with rituximab, cyclophosphamide, doxorubicin, vincristine, and dexamethasone (R-CHOP) were prescribed after surgery. Re-examination using PET/CT showed lack of hypermetabolic tumor recurrence signs, and the presence of multiple slightly large lymph nodes in the lateral iliac vessels and inguinal regions, but without significant lymph node metabolism increases. To date, only fifteen cases of primary diffuse large B-cell lymphoma of the urethra (including this one) have been reported in the literature. Therefore, we reviewed the etiology, clinical manifestations, diagnosis, differential diagnosis, treatment, and prognosis of DLBCL based on the existing literature to help characterize this rare disease.

Challenges and Opportunities in the Management of Diffuse Large B-Cell Lymphoma in Older Patients

Most patients with diffuse large B-cell lymphoma (DLBCL) are diagnosed at age 60 years or older. Challenges to effective therapy among older individuals include unfavorable biologic features of DLBCL, geriatric vulnerabilities, suboptimal treatment selection, and toxicities of cytotoxic chemotherapy. Wider application of geriatric assessments may help identify fit older patients who benefit from standard immunochemotherapy without unnecessary dose reductions. Conversely, attenuated regimens may provide a better balance of risk and benefit for selected unfit or frail patients. Supportive care with the use of corticosteroid-based prephase, prophylactic growth factors, and early institution of supportive and palliative care can help maximize treatment tolerance. Several novel or emerging therapies have demonstrated favorable toxicity profiles, thus facilitating effective treatment for elderly patients. In the relapsed or refractory setting, patients who are not candidates for stem cell transplantation can benefit from newly approved options including polatuzumab vedotin-based combinations or tafasitamab plus lenalidomide, which may have higher efficacy and/or lower toxicity than historical chemotherapy regimens. Chimeric antigen receptor T-cell therapy has been successfully applied to older patients outside of clinical trials. In the first-line setting, emerging immunotherapy options (bispecific antibodies) and targeted therapies (anti-CD20 antibodies combined with lenalidomide and/or B-cell receptor inhibitors) may provide chemotherapy-free approaches for DLBCL. Enrolling older patients in clinical trials will be paramount to fully examine potential efficacy and toxicity of these strategies. In this review, we discuss recent advances in fitness stratification and therapy that have expanded curative options for older patients, as well as future opportunities to improve outcomes in this population. IMPLICATIONS FOR PRACTICE: Management of diffuse large B-cell lymphoma in older patients poses challenges due to aggressive disease biology and geriatric vulnerability. Although R-CHOP remains standard first-line treatment, geriatric assessment may help evaluate patients' fitness for immunochemotherapy. Corticosteroid prephase, prophylactic growth factors, and early palliative care can improve tolerance of treatment. Novel salvage options (polatuzumab vedotin-based combinations, tafasitamab plus lenalidomide) or chimeric antigen receptor T-cell therapy should be considered in the relapsed or refractory setting for patients ineligible for stem cell transplantation. Emerging immunotherapies (bispecific antibodies) and targeted therapies provide potential first-line chemotherapy-free approaches, which need to be rigorously assessed in clinical trials that involve geriatric patients.

Multiple cutaneous ulcers revealing a primary cutaneous Epstein-Barr virus-positive diffuse large B-cell lymphoma

Primary cutaneous EBV-positive diffuse large B-cell lymphoma is an exceptional and aggressive neoplasia with a poorer prognosis than other cutaneous lymphoma. Our observation points out the rarity of the presentation and the dismal clinical course.

Infectious mononucleosis mimicking Epstein-Barr virus positive diffuse large B-cell lymphoma not otherwise specified

The Epstein–Barr virus (EBV) causes infectious mononucleosis (IM). In the case of atypical presentation, lymph node and tonsillar biopsies are required to rule out lymphoma. Here, we discuss an 83-year-old male who presented with findings suggestive of diffuse large B-cell lymphoma, which was later ruled out in favor of IM. The distinction between IM and lymphomas is quite challenging due to the extensive overlap between the two diseases. Various studies have demonstrated that EBV-positive diffuse large B-cell lymphoma mimics IM due to large B-cell proliferation in acute EBV infection. We suggest testing for acute EBV infection in addition to utilizing advanced testing to confirm IM in patients with atypical infection, to avoid misdiagnosis leading to inappropriate treatment.