A look into the evolution of Epstein-Barr virus-induced lymphoproliferative disorders: a case study

IGHV mutational status of nodal marginal zone lymphoma by NGS reveals distinct pathogenic pathways with different prognostic implications

The precise B cell of origin and molecular pathogenesis of nodal marginal zone lymphoma (NMZL) remain poorly defined. To date, due to the rarity of NMZL, the vast majority of already-published studies have been conducted on a limited number of samples and the technical approach to analyze the immunoglobulin genes was of amplifying rearranged variable region genes with the classical direct sequencing of the PCR products followed by cloning. Here, we studied the B cell Ig heavy-chain repertoires by next-generation sequencing (NGS) in 30 NMZL cases. Most of the cases were mutated (20/28; 71.5%) with homologies to the respective germ line genes ranging from 85 to 97, 83%, whereas 8/28 (28.5%) were unmutated. In addition, our results show that NMZL cases have a biased usage of specific immunoglobulin heavy-chain variable (IGHV) region genes. Moreover, we documented intraclonal diversity in all (100%) of the mutated cases and ongoing somatic hypermutations (SHM) have been confirmed by hundreds of reads. We analyzed the mutational pattern to detect and quantify antigen selection pressure and we found a positive selection in 4 cases, whereas in the remaining cases there was an unspecific stimulation. Finally, the disease-specific survival and the progression-free survival were significantly different between cases with mutated and unmutated IGHV genes, pointing out mutational status as a possible new biomarker in NMZL.

Molecular switch from MYC to MYCN expression in MYC protein negative Burkitt lymphoma cases

MYC is the most altered oncogene in human cancer, and belongs to a large family of genes, including MYCN and MYCL. Recently, while assessing the degree of correlation between MYC gene rearrangement and MYC protein expression in aggressive B-cell lymphomas, we observed few Burkitt lymphoma (BL) cases lacking MYC protein expression despite the translocation involving the MYC gene. Therefore, in the present study we aimed to better characterize such cases. Our results identified two sub-groups of MYC protein negative BL: one lacking detectable MYC protein expression but presenting MYCN mRNA and protein expression; the second characterized by the lack of both MYC and MYCN proteins but showing MYC mRNA. Interestingly, the two sub-groups presented a different pattern of SNVs affecting MYC gene family members that may induce the switch from MYC to MYCN. Particulary, MYCN-expressing cases show MYCN SNVs at interaction interface that stabilize the protein associated with loss-of-function of MYC. This finding highlights MYCN as a reliable diagnostic marker in such cases. Nevertheless, due to the overlapping clinic, morphology and immunohistochemistry (apart for MYC versus MYCN protein expression) of both sub-groups, the described cases represent bona fide BL according to the current criteria of the World Health Organization.

[Prevalence and clinico-pathological characteristics in patients with Epstein-Barr virus-positive diffuse large B-cell lymphoma in a high complexity hospital in Cali, Columbia]

INTRODUCTION

Diffuse large B-cell lymphoma (DLBCL) accounts for 35% of non-Hodgkin lymphoma and its incidence increases with age. Epstein Barr virus (EBV) is widely spread worldwide. There is a 10% association between EBV and DLBCL in immunocompetent patients; this type of malignancy has a high prevalence in Latin American countries.

OBJECTIVE

Estimate the percentage of association between DLBCL and EBV patients, describing demographics, clinical and immunological features, as well as phenotype and clinical outcome in a high complexity healthcare institution in Colombia.

MATERIALS AND METHODS

This is an analytic observational study from an historical cohort. Clinical and pathological records were revised among DLBCL patients and subsequent in-situ hybridization was performed for EBV detection. A descriptive analysis of the data was carried out.

RESULTS

From 2011 to 2017, 55 DLBCL patients were identified. 16% were positive on ISH for EBV, most of which belonged to the non-germinal center B-cell immunophenotype (89%), with a nodal presentation (56%). DLBCL EBV positive was more prevalent among males (67%) and in younger patients (median of 48 years) where the mortality rate was 56%.

CONCLUSIONS

DLBCL patients positive for EBV are more prone to belong to the non-germinal center B-cell immunophenotype which, according to our findings, is associated with a younger age and worse prognosis. Presently, EBER in-situ hybridization is not a part of routine tests, but we recommend its inclusion in the pathology package for DLBCL patients, as it can influence clinical outcomes.

Myeloid transformation of plasma cell myeloma: molecular evidence of clonal evolution revealed by next generation sequencing

Background

Plasma cell myeloma (PCM) is a neoplasm of terminally differentiated B lymphocytes with molecular heterogeneity. Although therapy-related myeloid neoplasms are common in plasma cell myeloma patients after chemotherapy, transdifferentiation of plasma cell myeloma into myeloid neoplasms has not been reported in literature. Here we report a very rare case of myeloid neoplasm transformed from plasma cell myeloma.

Case presentation

A 60-year-old man with a history of plasma cell myeloma with IGH-MAF gene rearrangement and RAS/RAF mutations developed multiple soft tissue lesions one year following melphalan-based chemotherapy and autologous stem cell transplant. Morphological and immunohistochemical characterization of the extramedullary disease demonstrated that the tumor cells were derived from the monocyte-macrophage lineage. Next generation sequencing (NGS) studies detected similar clonal aberrations in the diagnostic plasma cell population and post-therapy neoplastic cells, including IGH-MAF rearrangement, multiple genetic mutations in RAS signaling pathway proteins, and loss of tumor suppressor genes. Molecular genetic analysis also revealed unique genomic alterations in the transformed tumor cells, including gain of NF1 and loss of TRAF3.

Conclusion

To our knowledge, this is the first case of myeloid sarcoma transdifferentiated from plasma cell neoplasm. Our findings in this unique case suggest clonal evolution of plasma cell myeloma to myeloma neoplasm and the potential roles of abnormal RAS/RAF signaling pathway in lineage switch or transdifferentiation.

Clinicopathologic features of adult EBV-associated B-cell lymphoproliferative disease

In the present study, 21 cases of adult/late-onset EBV-associated lymphoproliferative disease (AELPD) with an uncertain malignant potential were investigated with regard to their histomorphology, immunophenotype, clonal rearrangement of the heavy chain (IgH) and T-cell receptor (TCR) genes and clinical course. The cases were histomorphologically reevaluated and assigned to one of three morphological groups: mononucleosis-like, Hodgkin-like, or polymorphous. In addition, cases with or without detectable necrosis were investigated for differences in clinical outcome. Overall survival was highest in the group with Hodgkin-like morphology (4/4 patients), followed by patients with mononucleosis-like phenotype (4/5 patients surviving). Cases with polymorphous morphology showed the poorest survival rates with 7/12 patients dead of disease (58%). 4/6 patients with histologically detectable necrosis died (66%), but only 4/15 patients without necrosis (27%). 11/21 cases with AELPD showed clonal rearrangement for IgH (n = 4), TCR (n = 5) or IgH + TCR (n = 2). 5/11 patients with clonal rearrangement died (45%), and this percentage was similar in all of the three subgroups. In conclusion, the present study shows that polymorphous morphology and detection of necrosis in AELPD are frequently linked to a fatal clinical course, whereas Hodgkin-like morphology seems to be associated with a more favourable prognosis. Clonal rearrangement of IgH or TCR is frequent in AELPD, but prognosis is unpredictable from this feature.

Preferential Usage of Specific Immunoglobulin Heavy Chain Variable Region Genes With Unmutated Profile and Advanced Stage at Presentation Are Common Features in Patients With Chronic Lymphocytic Leukemia From Senegal

OBJECTIVES

Chronic lymphocytic leukemia (CLL) is the most common type of leukemia in Western populations, being rarer in Asian and African people. It has been suggested that patients with CLL from Africa might have a more aggressive disease compared with white patients. In this study, we aimed to identify genetic factors that may account for this difference.

METHODS

We analyzed immunoglobulin heavy chain (IGH) genes' mutational status by performing next-generation sequencing in 25 Senegalese and 50 Italian patients with CLL.

RESULTS

We found that Senegalese patients more frequently had adverse prognostic factors and an unmutated profile. Furthermore, we documented that IGHV1 (IGHV1-69), IGHD3, and IGHJ6 were significantly more frequent in Senegalese patients, whereas IGHV3-30 was common and limited to the Italian cohort. Stereotyped receptors commonly detected in the white population were not recorded in our Senegalese series.

CONCLUSIONS

The different IGH repertoire we observed in the Senegalese cohort may reflect the diverse genetic and microenvironmental (ie, polymicrobial stimulation) background.

Epstein-Barr virus lytic cycle involvement in diffuse large B cell lymphoma

Epstein-Barr virus (EBV)-mediated B cell transformation is achieved predominantly through the action of latent proteins, but recent evidence suggests that lytic EBV replication has also a certain pathogenic role in lymphomagenesis, at least in the early phases of cell transformation. Particularly, in diffuse large B cell lymphoma (DLBCL), the EBV lytic cycle is by and large unexplored, so to disclose lytic cell contribution to lymphomagenesis, our aim was to evaluate viral early and late lytic gene expression in relation to several immune response markers in a series of EBV+ DLBCL from Argentina. An unexpected number of cells expressed lytic transcripts, being transcribed at the BZLF1, BHRF1, and BLLF1 locus, by real-time quantitative polymerase chain reaction. This lytic antigen expression was confirmed by immunohistochemical staining for BMRF1 early lytic protein, and a positive correlation between lytic and latent genes was confirmed, revealing a close link between their expressions in EBV+ DLBCL pathogenesis. Remarkably, BZLF1 displayed a negative correlation with CD4 cell counts, and this could be in part justified by the restriction of antigen presentation previously reported. The direct correlation for the late lytic gene BLLF1 and IFNγ in this series could represent a specific response directed towards this antigen. Interleukin 10 transcripts also displayed a positive correlation with lytic expression, indicating that regulatory mechanisms could be also involved on EBV-associated DLBCL pathogenesis in our series. Complete lytic reactivation in EBV-positive tumours could potentially kill EBV-positive malignant cells, providing a tool to promote tumour cell killing mediated by EBV as a complementary treatment strategy.

A Rare Case of Three Distinct Epstein-Barr Virus Associated Lymphoproliferative Disorders Over Sixteen Years of Human Immunodeficiency Virus Infection

Epstein Barr virus (EBV) is well known to cause different types of malignancies. In immunocompromised patients, such as those infected with human immunodeficiency virus (HIV), there is a higher likelihood of EBV related malignant transformation. Diagnosis of EBV related malignancies may be difficult and sometimes requires clinical and pathological correlation. It is very rare to have more than one type of EBV related malignancy in a single patient. Until now, there are no specific guidelines for treatment of EBV related malignancies and lymphoproliferative disorders (LPD). We present a patient who developed three different types of EBV related LPD during a sixteen-year course of HIV infection.

EBV-Negative Monomorphic B-Cell Posttransplant Lymphoproliferative Disorder with Marked Morphologic Pleomorphism and Pathogenic Mutations in ASXL1, BCOR, CDKN2A, NF1, and TP53

Posttransplant lymphoproliferative disorders (PTLDs) are a diverse group of lymphoid or plasmacytic proliferations frequently driven by Epstein-Barr virus (EBV). EBV-negative PTLDs appear to represent a distinct entity. This report describes an unusual case of a 33-year-old woman that developed a monomorphic EBV-negative PTLD consistent with diffuse large B-cell lymphoma (DLBCL) 13 years after heart-lung transplant. Histological examination revealed marked pleomorphism of the malignant cells including nodular areas reminiscent of classical Hodgkin lymphoma (cHL) with abundant large, bizarre Hodgkin-like cells. By immunostaining, the malignant cells were immunoreactive for CD45, CD20, CD79a, PAX5, BCL6, MUM1, and p53 and negative for CD15, CD30, latent membrane protein 1 (LMP1), and EBV-encoded RNA (EBER). Flow cytometry demonstrated lambda light chain restricted CD5 and CD10 negative B-cells. Fluorescence in situ hybridization studies (FISH) were negative for cMYC, BCL2, and BCL6 rearrangements but showed deletion of TP53 and monosomy of chromosome 17. Next-generation sequencing studies (NGS) revealed numerous genetic alterations including 6 pathogenic mutations in ASXL1, BCOR, CDKN2A, NF1, and TP53(x2) genes and 30 variants of unknown significance (VOUS) in ABL1, ASXL1, ATM, BCOR, BCORL1, BRNIP3, CDH2, CDKN2A, DNMT3A, ETV6, EZH2, FBXW7, KIT, NF1, RUNX1, SETPB1, SF1, SMC1A, STAG2, TET2, TP53, and U2AF2.

Unveiling Another Missing Piece in EBV-Driven Lymphomagenesis: EBV-Encoded MicroRNAs Expression in EBER-Negative Burkitt Lymphoma Cases

Epstein–Barr virus (EBV) is a gammaherpesvirus linked to a number of lymphoid and epithelial malignancies, including Burkitt lymphoma (BL) in which its frequency ranges from 30% in sporadic cases to 100% in the endemic ones. The possible contribution of EBV to BL pathogenesis is largely unknown. It has been suggested that EBV may be associated with all of the cases, including those diagnosed as EBV negative by a mechanism of hit-and-run. Early during oncogenesis, viral genes are essential for initiating disease. Progressively, viral genome is lost to escape the immune system and host mutations accumulate in proto-oncogenic cell. The main problem with the hit-and-run hypothesis is the lack of evidence in primary tumors. The routine methods applied to detect the virus [i.e., immunohistochemistry and EBV-encoded RNAs (EBER) in situ hybridization (ISH)] have a low specificity and accuracy. The aim of this study was to identify the most suitable method to detect EBV infection in pathology samples by applying conventional and non-conventional methods (i.e., EBV-microRNAs detection and EBV viral load measurement). We investigated a total of 10 cases and we found that all the samples (n = 6) diagnosed as EBV negative by immunohistochemistry and EBER-ISH demonstrated the presence of EBV-microRNAs and EBV genome. This points at the possibility that EBV might have contributed to lymphomagenesis in all our patients, and propose microRNAs detection as the most specific and sensitive tool to recognize EBV vestiges. It is worth noting that our data would have considerable implications for EBV-related diseases control. By using anti-EBV vaccines, one could potentially prevent also some cancers less suspected of a viral origin because of viral genome loss.

Coexistence of age-related EBV-associated follicular hyperplasia and large B-cell EBV+ lymphoma of the elderly. Two distinct features of the same T-cell dysfunction related to senescence?

Age-related EBV-associated lymphoproliferative disorders form a new clinicopathological group. Until recently, this group was associated with diffuse large B-cell lymphoma (DLBCL), characterised by an aggressive clinical presentation and a poor prognosis. Recent findings in Western Caucasian patients, however, suggest that this entity covers a wide spectrum of diseases, ranging from reactive follicular hyperplasia (HR) to DLBCL. We report the case of an 85-year-old Caucasian man showing lymphadenopathy and numerous hypodense lesions of the liver. Examination of a lymph node revealed follicular hyperplasia with EBV expression confined to germinal centres. The patient was treated with Rituximab and subsequently, the lesions of the liver were explored. They showed extensive necrosis and a polymorphic large B-cell population with strong EBV expression. This is the first report to describe age-related EBV-associated follicular hyperplasia at one site coexisting with DLBCL at another. This case warrants undertaking further investigations each time a diagnosis of age-related EBV-HR is associated with extranodal lesions.

Recent insights in the pathogenesis of post-transplantation lymphoproliferative disorders

Post-transplant lymphoproliferative disorder (PTLD) is an aggressive complication of solid organ and hematopoietic stem cell transplantation that arises in up to 20% of transplant recipients. Infection or reactivation of the Epstein-Barr virus (EBV), a ubiquitous human herpesvirus, in combination with chronic immunosuppression are considered as the main predisposing factors, however insight in PTLD biology is fragmentary. The study of PTLD is complicated by its morphological heterogeneity and the lack of prospective trials, which also impede treatment optimization. Furthermore, the broad spectrum of underlying disorders and the graft type represent important confounding factors. PTLD encompasses different malignant subtypes that resemble histologically similar lymphomas in the general population. Post-transplant diffuse large B-cell lymphoma (PT-DLBCL), Burkitt lymphoma (PT-BL) and plasmablastic lymphoma (PT-PBL) occur most frequently. However, in many studies various EBV⁺ and EBV^- PTLD subtypes are pooled, complicating the interpretation of the results. In this review, studies of the gene expression pattern, the microenvironment and the genetic profile of PT-DLBCL, PT-BL and PT-PBL are summarized to better understand the mechanisms underlying post-transplantation lymphomagenesis. Based on the available findings we propose stratification of PTLD according to the histological subtype and the EBV status to facilitate the interpretation of future studies and the establishment of clinical trials.

Langerhans cell sarcoma following marginal zone lymphoma: expanding the knowledge on mature B cell plasticity

The concept of unidirectional differentiation of the haematopoietic stem cell has been challenged after recent findings that human B cell progenitors and even mature B cells can be reprogrammed into histiocytic/dendritic cells by altering expression of lineage-associated transcription factors. The conversion of mature B cell lymphomas to Langerhans cell neoplasms is not well documented. Three previous reports have described clonally related follicular lymphoma and Langerhans cell tumours, whereas no case has been published of clonally related marginal zone lymphoma and Langerhans cell sarcoma. We describe the case of a 77-year-old patient who developed a Langerhans cell sarcoma and 6 years later a nodal marginal zone lymphoma. Mutation status examination showed 100 % gene identity to the germline sequence, suggesting direct trans-differentiation or dedifferentiation of the nodal marginal zone lymphoma to the Langerhans cell sarcoma rather than a common progenitor. We found inactivation of paired box 5 (PAX-5) in the lymphoma cells by methylation, along with duplication of part of the long arm of chromosomes 16 and 17 in the sarcoma cells. The absence of PAX-5 could have triggered B cells to differentiate into macrophages and dendritic cells. On the other hand, chromosomal imbalances might have activated genes involved in myeloid lineage maturation, transcription activation and oncogenesis. We hypothesize that this occurred because of previous therapies for nodal marginal zone lymphoma. Better understanding of this phenomenon may help in unravelling the molecular interplay between transcription factors during haematopoietic lineage commitment and may expand the spectrum of clonally related mature B cell neoplasms and Langerhans cell tumours.