Human Herpes Virus 8/Epstein-Barr Virus-Copositive, Plasmablastic Microlymphoma Arising in Multicentric Castleman's Disease of an Immunocompetent Patient

Epstein-Barr virus reactivation influences clonal evolution in human herpesvirus-8-related lymphoproliferative disorders

Background

Human herpesvirus‐8 (HHV8) is a lymphotropic virus associated with different lymphoproliferative disorders, including primary effusion lymphoma (PEL), multicentric Castleman’s disease (MCD), diffuse large B‐cell lymphomas, not otherwise specified, and the rare entity known as germinotropic lymphoproliferative disorder (GLPD). In PELs and GLPD the neoplastic cells also contain Epstein–Barr virus (EBV). In addition, occasional cases with atypical and overlapping features among these entities have been recognised, suggesting that the spectrum of the HHV8‐related lesions may not be fully characterised.

Aims

Here, we report two cases of lymphoproliferative disorder associated with HHV8 and EBV that further expand the spectrum of HHV8/EBV‐positive lymphoproliferative disease.

Methods and results

Case 1 represented HHV8/EBV‐positive extracavitary nodal PEL followed by pleural PEL. The striking characteristic of this case was the almost focal and intrasinusoidal localisation of the neoplastic cells and the association with Castleman’s disease features. In the second case, we found the entire spectrum of HHV8‐related disorders, i.e. MCD, GLPD, and PEL, coexisting in the same lymph node, underlining the variability, possible overlap and evolution among these entities. Both cases were well analysed with immunohistochemistry, determination of the EBV latency programme, and molecular analysis for clonality of immnoglobulin genes. In both patients, the disease followed an unexpected indolent course, both being still alive after 8 and 12 months, respectively.

Conclusion

Our findings represent further evidence of the overlap among HHV8/EBV‐positive lymphoproliferative disorders, and underline a grey zone that requires further study; they further confirm the experimental evidence that lytic EBV replication influences HHV8‐related tumorigenesis.

Human herpesvirus 8-positive multicentric Castleman disease with germinotropic plasmablastic aggregates: Overlapping spectrum of human herpesvirus 8-associated lymphoproliferative disorder

The diagnosis of human herpesvirus 8 (HHV8)-associated lymphoproliferative disorder (LPD) is challenging because of the rarity and extended spectrum of each entity. A 43-year-old, human immunodeficiency virus seropositive, Japanese man was referred to our department because of persistent fever, generalized lymphadenopathy, jaundice and anasarca. Biopsy of a left axially lymph node demonstrated relatively preserved nodal structure with multicentric Castleman disease (MCD) features. In the germinal center, there were aggregates of HHV8-infected plasmablasts that were diffusely positive for CD38, MUM1/IRF4, LCA, IgM and λ; partially positive for CD30, c-MYC, p53; and negative for CD138, CD20, PAX-5, κ, CD2, CD3 and CD5. A small number of Epstein-Barr virus encoded small RNA (EBER)-positive large cells infiltrated in the outer part of the germinal center and the mantle layer, but the cells copositive for EBER and HHV8 were not evident. We diagnosed the patient as HHV8-positive MCD with germinotropic plasmablastic aggregates, which demonstrated intermediate pathologic features between HHV8-positive MCD and germinotropic lymphoproliferative disorder. The pathogenesis of each HHV8-associated LPD differs in cellular origin, host immune status, cytoplasmic immunoglobulin expression, clonality pattern and EBV infection; however, these factors sometimes overlap and induce extended clinical and pathologic presentations.

Germinotropic lymphoproliferative disorder: a systematic review

Germinotropic lymphoproliferative disorder is a rare and rather enigmatic novel entity with distinctive clinicopathological features, one of which is the typical co-infection by Human herpesvirus 8 and Epstein-Barr virus. Human herpesvirus 8 is a lymphotropic virus detected in Kaposi sarcoma, multicentric Castleman disease, primary effusion lymphoma, Human herpesvirus 8-positive diffuse large B cell lymphoma not otherwise specified, and germinotropic lymphoproliferative disorder. Co-infection by Human herpesvirus 8 and Epstein-Barr virus is identified only in two lymphoproliferative diseases: germinotropic lymphoproliferative disorder and primary effusion lymphoma, which are otherwise diseases with totally different clinical presentations and outcomes. Unlike primary effusion lymphoma mostly occurring in immunocompromised individuals and following an aggressive course, germinotropic lymphoproliferative disorder usually presents with single or multiple lymphadenopathy affecting mainly immunocompetent individuals and mostly follows an indolent course. Based on the PRISMA guidelines, we carried out a systematic search on PubMed/MEDLINE, Web of Science, Scopus, EMBASE, and Cochrane Library using the search terms "germinotropic" and "lymphoproliferative disorder." Current scientific literature reports just 19 cases of germinotropic lymphoproliferative disorder. The purpose of our systematic review is to improve our understanding of the disease, focusing on epidemiology, clinical presentation, pathological features, treatment, and outcome. In addition, we discuss the differential diagnosis with the other Human herpesvirus 8-related lymphoproliferative diseases as currently recognized in the World Health Organization classification, adding a focus on lymphoproliferative disorders showing overlapping features.

EBV-Associated Lymphoproliferative Disorders: Update in Classification

Although about 90% of the world's population is infected by EBV only a small subset of the related infections result in neoplastic transformation. EBV is a versatile oncogenic agent involved in a multitude of hematopoietic, epithelial, and mesenchymal neoplasms, but the precise role of EBV in the pathogenesis of many of the associated lymphoid/histiocytic proliferations remains hypothetical or not completely understood. Additional studies and use of evolving technologies such as high-throughput next-generation sequencing may help address this knowledge gap and may lead to enhanced diagnostic assessment and the development of potential therapeutic interventions.

Epstein-Barr virus (EBV)-associated lymphoid proliferations, a 2018 update

Epstein-Barr virus (EBV) has been linked to many human neoplasms including hematopoietic, epithelial, and mesenchymal tumors. Since our original review of EBV-associated lymphoproliferative disorders in 2007, many advances and developments have been reported. In this review, we will examine the recent advances in EBV-associated lymphoid/histiocytic proliferations, dividing them into reactive, B cell, T/NK cell, immunodeficiency-related, and histiocytic/dendritic cell proliferations.

Persistent KSHV Infection Increases EBV-Associated Tumor Formation In Vivo via Enhanced EBV Lytic Gene Expression

The human tumor viruses Epstein-Barr virus (EBV) and Kaposi sarcoma-associated herpesvirus (KSHV) establish persistent infections in B cells. KSHV is linked to primary effusion lymphoma (PEL), and 90% of PELs also contain EBV. Studies on persistent KSHV infection in vivo and the role of EBV co-infection in PEL development have been hampered by the absence of small animal models. We developed mice reconstituted with human immune system components as a model for KSHV infection and find that EBV/KSHV dual infection enhanced KSHV persistence and tumorigenesis. Dual-infected cells displayed a plasma cell-like gene expression pattern similar to PELs. KSHV persisted in EBV-transformed B cells and was associated with lytic EBV gene expression, resulting in increased tumor formation. Evidence of elevated lytic EBV replication was also found in EBV/KSHV dually infected lymphoproliferative disorders in humans. Our data suggest that KSHV augments EBV-associated tumorigenesis via stimulation of lytic EBV replication.