Role of MYD88 in lymphoplasmacytic lymphoma diagnosis and pathogenesis

MYD88 mutation-positive indolent B-cell lymphoma with CNS involvement: Bing-Neel syndrome mimickers

MYD88 p.L265P mutation occurs in over 90% of Waldenström's macroglobulinemia (WM), which is characterized by lymphoplasmacytic lymphoma (LPL) with monoclonal IgM. WM requires careful diagnosis due to overlapping features with other B-cell malignancies. Bing-Neel syndrome (BNS), a rare complication of WM, involves central nervous system (CNS) invasion. This report describes two cases of morphologically low-grade B-cell lymphoma in the bone marrow accompanied by the presence of a large B-cell lymphoma in the brain and a common MYD88 p.L265P mutation, which were eventually established as BNS mimickers. Although the two components in these cases showed the same identical light-chain restriction, different immunoglobulin heavy-chain rearrangement peaks indicated distinct lymphoma stem cells for CNS and bone marrow lesions. These clinical cases emphasize the challenges in diagnosing BNS. Based on the findings, biopsy is recommended for accurate identification of the clonal relationship and MYD88 mutation status.

Good clinical response following Ibrutinib treatment of a rare case of lymphoplasmacytic lymphoma secreting IgA kappa paraprotein: A case report

Lymphoplasmacytic lymphoma (LPL) is a malignant proliferation of small lymphocytes, lymphoplasmocytoid cells and plasmocytes affecting the bone marrow, lymph nodes and spleen. Its incidence is 1/100,000 and represents 8% of all lymphomas. A total of ~5% of patients with LPL may secrete non-IgM of IgG, IgA, kappa or lambda type or be non-secretory. In the present study, a case of a 62-year-old female patient who was diagnosed with non-IgM LPL with kappa light chain monoclonal paraprotein production and normal serum immunoglobulin levels was reported. The MYD88 L265P mutation was detected by molecular genetic analysis using a sample of the bone marrow. The patient underwent initial treatment with a combination of Bendamustine-Rituximab, and later on, Ibrutinib (a Bruton kinase inhibitor) was added to the treatment protocol. The authors' aim was to describe a case of a rare type of LPL studied and cured at the University Hospital 'St. Ivan Rilski', as well as to show the methods used for its diagnosis and their applicability. The difficulty in diagnosing such rare cases of LPL which are associated with marked plasmacytic differentiation and IgA paraprotein secretion resembling plasma cell neoplasia was addressed. From the other side, the characteristic features in favor of LPL diagnosis are the immunophenotype profile of plasmocytes, as well as the presence of MYD88 L265P mutation. Finally, the methods of management and treatment of this type of lymphoma were reported, highlighting the favorable effect of the treatment with Bruton TK inhibitor (Ibrutinib).

Diagnosing Vitreoretinal Lymphomas-An Analysis of the Sensitivity of Existing Tools

Simple Summary

Diagnostics of vitreoretinal lymphoma is very challenging, as the possibility of receiving false negative results is common. We retrospectively analyzed the sensitivity of the most commonly used diagnostic methods including ancillary immunohistochemistry, Myeloid Differentiation Factor 88 (MyD88) L256P mutation analysis, polymerase chain reaction (PCR) for monoclonal rearrangements of immunoglobulin heavy chain (IgH) and T-cell Receptor (TCR) genes, flow cytometry, and IL10 and IL6 analysis, to diagnose vitreoretinal lymphomas from published data in the literature. MyD88 mutation analysis caused by a hotspot mutation in MyD88 was the most sensitive and had the lowest coefficient of variation.

Abstract

Vitreoretinal lymphoma (VRL) is a rare ocular pathology that is notorious for mimicking chronic uveitis, which is a seemingly benign condition in comparison. The most common form of VRL is the diffuse large B-cell type, and there has been a high mortality rate. This dismal prognosis can be improved significantly if the disease is diagnosed early, but until now there is no consensus on an appropriate diagnostic algorithm. We conducted a retrospective search of PubMed Central^® and analyzed results from thirty-three studies that were published between 2011–2021. The chosen studies incorporated some popular testing tools for VRL, and our analyses focused on comparing the average sensitivity of five diagnostic methods. The methods included cytology including ancillary immunohistochemistry, Myeloid Differentiation Factor 88 (MyD88) mutation analysis, polymerase chain reaction (PCR) for monoclonal rearrangements of immunoglobulin heavy chain (IgH) and T-cell Receptor (TCR) genes, flow cytometry, and IL10 and IL6 analysis. Across the varied diagnostic methods employed in thirty-three studies explored in this analysis, MyD88 mutation assay emerged as a strong contender given its sensitivity and low coefficient of variation. There is an imminent need for the introduction of newer assays that can further improve the sensitivity of identifying MyD88 mutation in cancer cells seen in the vitreous.

Clarifying the molecular mechanism of tomentosin‑induced antiproliferative and proapoptotic effects in human multiple myeloma via gene expression profile and genetic interaction network analysis

Multiple myeloma (MM) is an aggressive B cell malignancy. Substantial progress has been made in the therapeutic context for patients with MM, however it still represents an incurable disease due to drug resistance and recurrence. Development of more effective or synergistic therapeutic approaches undoubtedly represents an unmet clinical need. Tomentosin is a bioactive natural sesquiterpene lactone extracted by various plants with therapeutic properties, including anti‑neoplastic effects. In the present study, the potential antitumor activity of tomentosin was evaluated on the human RPMI‑8226 cell line, treated with increasing tomentosin concentration for cytotoxicity screening. The data suggested that both cell cycle arrest and cell apoptosis could explain the antiproliferative effects of tomentosin and may result in the inhibition of RPMI‑8226 cell viability. To assess differentially expressed genes contributing to tomentosin activity and identify its mechanism of action, a microarray gene expression profile was performed, identifying 126 genes deregulated by tomentosin. To address the systems biology and identify how tomentosin deregulates gene expression in MM from a systems perspective, all deregulated genes were submitted to enrichment and molecular network analysis. The Protein‑Protein Interaction (PPI) network analysis showed that tomentosin in human MM induced the downregulation of genes involved in several pathways known to lead immune‑system processes, such as cytokine‑cytokine receptor interaction, chemokine or NF‑κB signaling pathway, as well as genes involved in pathways playing a central role in cellular neoplastic processes, such as growth, proliferation, migration, invasion and apoptosis. Tomentosin also induced endoplasmic reticulum stress via upregulation of cyclic AMP‑dependent transcription factor ATF‑4 and DNA damage‑inducible transcript 3 protein genes, suggesting that in the presence of tomentosin the protective unfolded protein response signaling may induce cell apoptosis. The functional connections analysis executed using the Connectivity Map tool, suggested that the effects of tomentosin on RPMI‑8226 cells might be similar to those exerted by heat shock proteins inhibitors. Taken together, these data suggested that tomentosin may be a potential drug candidate for the treatment of MM.

An Overview of Selected Rare B-Cell Lymphoproliferative Disorders: Imaging, Histopathologic, and Clinical Features

Lymphoproliferative disorders (LPD) are conditions characterized by the uncontrolled proliferation of B or T-cell lines. They encompass a wide spectrum of abnormalities, which may be broadly classified as reactive processes or malignant diseases, such as lymphoma, based on their cellular clonality and clinical behavior. While some of these disorders are rare, they may be encountered sporadically in clinical practice, causing diagnostic dilemmas owing to overlap in their clinical and imaging features with more common disorders. The updated 4th edition WHO classification of lymphoid neoplasms was released in 2016 to incorporate the rapid clinical, pathological, molecular biology and cytogenetic advances of some of these disorders. Despite these updates, very little information is presented in the literature from the radiology perspective. The aim of this article is to familiarize radiologists and other physicians with certain rare variants of B-cell lymphoproliferative disorders with a focus on imaging features of these disorders, as well as to provide an overview of some important updates contained within the new WHO classification of lymphoid neoplasms.

Point Mutation Specific Antibodies in B-Cell and T-Cell Lymphomas and Leukemias: Targeting IDH2, KRAS, BRAF and Other Biomarkers RHOA, IRF8, MYD88, ID3, NRAS, SF3B1 and EZH2

B-cell and T-cell lymphomas and leukemias often have distinct genetic mutations that are diagnostically defining or prognostically significant. A subset of these mutations consists of specific point mutations, which can be evaluated using genetic sequencing approaches or point mutation specific antibodies. Here, we describe genes harboring point mutations relevant to B-cell and T-cell malignancies and discuss the current availability of these targeted point mutation specific antibodies. We also evaluate the possibility of generating novel antibodies against known point mutations by computationally assessing for chemical and structural features as well as epitope antigenicity of these targets. Our results not only summarize several genetic mutations and identify existing point mutation specific antibodies relevant to hematologic malignancies, but also reveal potential underdeveloped targets which merit further study.

CXCR4 in Waldenström's Macroglobulinema: chances and challenges

It is one of the major aims in cancer research to improve our understanding of the underlying mechanisms which initiate and maintain tumor growth and to translate these findings into novel clinical diagnostic and therapeutic concepts with the ultimate goal to improve patient care. One of the greater success stories in this respect has been Waldenström's Macroglobulinemia (WM), which is an incurable B-cell neoplasm characterized by serum monoclonal immunoglobulin M (IgM) and clonal lymphoplasmacytic cells infiltrating the bone marrow. Recent years have succeeded to describe the molecular landscape of WM in detail, highlighting two recurrently mutated genes, the MYD88 and the CXCR4 genes: MYD88 with an almost constant and recurrent point mutation present in over 90% of patients and CXCR4 with over 40 different mutations in the coding region affecting up to 40% of patients. Intriguingly, both mutations are activating mutations leading in the case of CXCR4 to an indelible activation and perpetual signaling of the chemokine receptor. These data have shed light on the essential role of CXCR4 in this disease and have paved the way to use these findings for predicting treatment response to the Bruton tyrosine kinase (BTK) inhibitor ibrutinib and novel therapeutic approaches in WM, which might be transferable to other related CXCR4 positive diseases. Well known for its central role in cancer progression and distribution, CXCR4 is highlighted in this review with regard to its biology, prognostic and predictive relevance and therapeutic implications in WM.

Efficacy of Venetoclax and Dexamethasone in Refractory IgM Primary Plasma Cell Leukemia with t(11;14) and TP53 Mutation: A Case Report and Literature Review

Primary plasma cell leukemia (pPCL) is an uncommon disease. IgM multiple myeloma (MM) is an infrequent subtype that accounts for less than 1 percent of MM cases. IgM pPCL is quite rare with only a few cases published to date. We describe a case of a patient with IgM pPCL who initially presented with hyperviscosity syndrome requiring urgent plasma exchange. His bone marrow biopsy demonstrated t(11;14). He progressed on proteasome inhibitors, immunomodulating agents, and other chemotherapy medications but later achieved very good partial response (VGPR) to venetoclax and dexamethasone. Given the poor prognosis of pPCL, further studies using venetoclax alone or in combination with other novel agents as first-line treatment options are warranted particularly in patients with t(11;14).

Hepatitis C virus-associated non-Hodgkin lymphomas: the endless history

Hepatitis C virus (HCV) is a global population problem due to its high prevalence worldwide. In the prognosis of patients with HCV not only hepatic but increasingly frequent of extrahepatic HCV manifestations, such as mixed cryoglobulinemia (MC) and non-Hodgkin's lymphoma (NHL), are important. The role of the HCV virus in the pathogenesis of lymphoproliferative diseases is confirmed by a large number of epidemiological studies, as well as by the effectiveness of antiviral therapy in patients with non-Hodgkin's lymphoma (NHL). The purpose of the review was to provide an overview of epidemiological and biological data explaining the role of HCV in the development of NHL. The review also discusses HCV-associated NHL treatment by the traditional antiviral therapy (interferon and ribavirin) and by the new direct antiviral agents.

Identification of clinical molecular targets for childhood Burkitt lymphoma

Burkitt lymphoma (BL) is a malignant tumor in children. Although BL is generally curable, early relapse and refractoriness may occur. Some molecular indicators have been recently suggested for BL diagnosis, but large heterogeneity still exists. This study aimed at providing clinical molecular targets and methods that may help improve diagnosis and treatment of childhood BL. Only children patients were included in the study, and targeted gene sequencing was conducted to identify tumor specific mutations. The mRNA and protein level expression of potential target genes were measured by real-time PCR and immunohistochemistry. The relationship between BL specific gene mutation and differential expression with clinical features was analyzed. The results showed that i) detailed analysis of c-MYC/BCL2/BCL6 gene loci alteration and gene expression would help in accurate diagnosis and treatment determination of childhood BL; ii) loss-of-function mutations in SOCS1 or CIITA gene might be used as malignant markers for BL diagnosis and prognosis; iii) specific mutations of CD79A, MYD88, KLF2, DNMT3A and NFKBIE genes often concurrently existed in BL and showed association with benign clinical outcomes; iv) the high expression of MYC, TCF3 and loss-of-function ID3 genes in tumor may be potential therapeutic targets and could be used for treatment monitoring; and v) four MYC-translocation negative cases were re-defined as high-grade B-cell lymphoma-not otherwise specified (HGBL-NOS) but showed similar clinical outcomes and molecular features to other BL cases in the study, suggesting more studies needed to explore the molecular mechanisms and clinical significance of this provisional tumor entity.

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Detailed analysis of c-MYC/BCL2/BCL6 gene alteration and expression may help in accurate diagnosis and treatment;

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The MYC-translocation negative cases (HGBL-NOS) showed similar clinical outcomes and molecular features to other cases;

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Loss-of-function mutations of SOCS1 or CIITA gene could be used as malignant markers for diagnosis and prognosis;

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Concurrent mutations in CD79A, MYD88, KLF2, DNMT3A and NFKBIE genes associated with benign clinical outcomes;

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High expression of MYC, TCF3 and loss-of-function ID3 gene in tumor may be potential therapeutic targets.

Occurrence of lymphoplasmacytic lymphoma in a chronic myeloid leukemia patient following long-term treatment with tyrosine kinase inhibitors: A case report

INTRODUCTION

After tyrosine kinase inhibitors (TKIs) targeting BCR-ABL1 were introduced for the treatment of chronic myeloid leukemia, clinical outcomes have improved dramatically. However, together with the increase in the survival rate, a more frequent occurrence of secondary malignancies has been observed as well. TKIs have been demonstrated to be a risk factor of malignancies such as non-Hodgkin lymphoma, prostate cancer, and skin cancer. However, lymphoplasmacytic lymphoma (LPL) has never been reported as a secondary malignancy after TKI treatment in chronic myeloid leukemia (CML).

PATIENT CONCERNS

An 81-year-old male patient diagnosed with CML and treated with TKIs for a long period (15 years) was admitted due to a chief complaint of abdominal pain. A large abdominal mass was detected by imaging that included computed tomography.

DIAGNOSIS

LPL was confirmed from biopsies after ultrasonography and sigmoidoscopy. Serum IgM level was increased and M protein and monoclonal gammopathy, IgM_kappa light chain type were detected.

INTERVENTIONS

The patient received six cycles of R-CHOP chemotherapy.

OUTCOMES

After chemotherapy, he showed response. The sizes of the abdominal mass and lymph nodes decreased; moreover, serum M protein and IgM levels decreased, as well.

CONCLUSION

Herein, for the first time, we describe a patient who developed LPL as a secondary malignancy after administration of TKIs for the treatment of CML. Our observations indicate the importance of awareness of this secondary malignancy that can develop in CML patients treated with TKIs.

MYD88 L265P mutation analysis is a useful diagnostic adjunct for lymphoplasmacytic lymphoma with pleural effusion

Lymphoplasmacytic lymphoma (LPL) is a marrow-based lymphoma, rarely involving extramedullary sites, particularly the pleural cavities. The distinction of lymphomatous pleural effusion (PE) in LPL patients from benign effusion is challenging. We conducted this study to examine whether MYD88 L265P mutation analysis is useful in distinguishing benign from lymphomatous PE in four patients with LPL, in which the initial marrow specimens were all positive for MYD88 mutation. In one case each with plasma cell- or lymphocyte-predominant PE, MYD88 mutation was positive, confirming lymphomatous effusion. The other lymphocyte-predominant PE was negative for MYD88 mutation, but was clonally related to a previous nodal biopsy and this PE was also considered to have LPL involvement. The fourth case developed large B-cell lymphoma in the PE 30 months later. The PE specimen was negative for MYD88 mutation but was clonally related to the diagnostic marrow tissue, indicating large cell transformation. Four cases of small lymphocyte-predominant benign PE from patients without history of lymphoma were examined and were all negative for MYD88 L265P mutation. In conclusion, in this small case series we showed that MYD88 L265P mutation analysis could serve as a useful adjunct in distinguishing benign from lymphomatous PE in patients with LPL.

Characteristics of Waldenström Macroglobulinemia in Korean Patients According to Mutational Status of MYD88 and CXCR4: Analysis Using Ultra-Deep Sequencing

BACKGROUND

Little is known about the mutational frequency of myeloid differentiation factor 88 (MYD88) and C-X-C chemokine receptor type 4 (CXCR4) and the corresponding characteristics in Asian individuals afflicted with Waldenström macroglobulinemia (WM). We investigated the characteristics of WM according to mutational status of MYD88/CXCR4, and attempted to determine the lineage commitment among hematopoietic cells by MYD88^L265P single-cell sequencing on bone marrow (BM) smear slides.

MATERIALS AND METHODS

CXCR4 mutations (muts) were detected using ultra-deep sequencing using target capture. Mutational burden of MYD88 was assessed using real-time polymerase chain reaction. Single-cell sequencing for MYD88 was performed on lymphocytes, plasmacytoid lymphocytes, plasma cells, and neutrophils using laser microdissection.

RESULTS

Among 31 patients, the frequencies of MYD88/CXCR4 muts were as follows: MYD88 wild type (WT) CXCR4^WT (6 patients, 19.4%), MYD88^L265PCXCR4^WT (19 patients, 61.4%), MYD88^L265PCXCR4^mut (6 patients, 19.4%; 1 frameshift and 5 nonsense muts). Immunoglobulin M levels of MYD88^L265CXCR4^WT patients were significantly higher than those of MYD88^WTCXCR4^WT patients (P = .024). Tumor burden in BM was highest in patients with MYD88^L265PCXCR4^mut (82.0%), followed by MYD88^L265PCXCR4^WT (52.8%) and MYD88^WTCXCR4^WT (14.2%) (P < .001). The quantity of MYD88-mutated DNA tended to correlate with tumor burden in BM (correlation coefficient 0.647; P = .009). MYD88^L265P was detected in plasma cells, plasmacytoid lymphocytes, and lymphocytes but not neutrophils.

CONCLUSION

The frequency of MYD88/CXCR4 muts in Korean and Caucasian patients with WM was similar, however 5 of the 6 CXCR4 muts were nonsense-a proportion higher than reported frequencies in Caucasian individuals. Ultra-deep sequencing was capable of detecting CXCR4 muts not detectable using Sanger sequencing, suggesting a possible replacement of the B-cell sorting.

MYD88 and CXCR4 Mutation Profiling in Lymphoplasmacytic Lymphoma/Waldenstrom's Macroglobulinaemia

Recurrent mutations affecting MYD88 and CXCR4 gene nowadays form the basis for the diagnosis, risk stratification and use of inhibitors targeting these signalling pathways in LPL/WM which are rare B cell neoplasms. MYD88 L265P mutation analysis was performed on 33 cases of LPL/WM by AS-PCR (positivity-84.8%, n = 28/33) and by Sanger sequencing (positivity-39.3%, n = 13/33). We had only two cases with CXCR4 non-sense (NS) mutation (p.S338*) using Sanger sequencing. MYD88 (L265P) mutation detection by AS-PCR can form reliable biomarker for the diagnosis of LPL/WM in molecular labs. Although the cohort is small, still the CXCR4 mutation frequency in our study is low as compared to the published literature.

Analysis of Genomic Alteration in Primary Central Nervous System Lymphoma and the Expression of Some Related Genes

Primary central nervous system lymphoma (PCNSL) is a rare and special type of non-Hodgkin lymphoma. The treatment of PCNSL is comprehensive, combining surgery, radiotherapy, and chemotherapy. However, the outcome is poor because of its high invasiveness and rate of recurrence. We analyzed 22 cases of PCNSL using next-generation sequencing (NGS) to detect 64 candidate genes. We used immunohistochemical methods to analyze gene expression in 57 PCNSL samples. NGS showed that recurrent mutations in KMT2D and CD79B, components of the NF-κB pathway, accounted for 65% of total mutations in PCNSL samples. The most frequent mutated gene was PIM1 (77.27%, 17/22), followed by MYD88 (63.64%, 14/22), CD79B (69.09%, 13/22), and KMT2D (50.00%, 11/22). Mutations of the CD79B gene were associated with an inferior progression-free survival (PFS), and GNA13 gene mutations were associated with a shorter PFS and overall survival (OS) in PCNSL patients (P < .05). PIM1 and MYD88 were highly expressed in PCNSL patients and were related to their OS time. MYD88 overexpression might be an independent and poor prognostic predictor of OS time. In summary, we identified highly recurrent genetic lesions in CD79B and KMT2D, components of the NF-κB pathway, in PCNSL and validated the expression of PIM1 and MYD88 related to poor survival, thereby providing novel insights into the pathogenesis and precision medicine of PCNSL.

MyD88 Regulates the Expression of SMAD4 and the Iron Regulatory Hormone Hepcidin

The myeloid differentiation primary response gene 88 (MyD88) is an adaptive protein that is essential for the induction of inflammatory cytokines through almost all the Toll-like receptors (TLRs). TLRs recognize molecular patterns present in microorganisms called pathogen-associated molecular patterns. Therefore, MyD88 plays an important role in innate immunity since its activation triggers the first line of defense against microorganisms. Herein, we describe the first reported role of MyD88 in an interconnection between innate immunity and the iron-sensing pathway (BMP/SMAD4). We found that direct interaction of MyD88 with SMAD4 protein activated hepcidin expression. The iron regulatory hormone hepcidin is indispensable for the intestinal regulation of iron absorption and iron recycling by macrophages. We show that MyD88 induces hepcidin expression in a manner dependent on the proximal BMP responsive element on the hepcidin gene (HAMP) promoter. We identified the Toll/interleukin-1 receptor (TIR) domain of MyD88 as the domain of interaction with SMAD4. Furthermore, we show that BMP6 stimulation, which activates SMAD6 expression, also induces MyD88 proteosomal degradation as a negative feedback mechanism to limit hepcidin induction. Finally, we report that the MyD88 gain-of-function L265P mutation, frequently encountered in B-cell lymphomas such as Waldenström’s macroglobulinemia, enhances hepcidin expression and iron accumulation in B cell lines. Our results reveal a new potential role for MyD88 in the SMAD signaling pathway and iron homeostasis regulation.

High frequency and prognostic value of MYD88 L265P mutation in diffuse large B-cell lymphoma with R-CHOP treatment

The aim of this study was to analyze the prevalence and prognostic value of myeloid differentiation factor 88 (MYD88) L265P in diffuse large B-cell lymphoma (DLBCL) patients treated with rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP). We assessed the MYD88 L265P mutation using an allele-specific semi-nested polymerase chain reaction method in 53 DLBCL patients treated with R-CHOP. The MYD88 L265P mutation was detected in 16 of 53 DLBCL (30.19%) samples from patients treated with R-CHOP. Age and location were statistically significantly associated with MYD88 L265P (P=0.025, 0.033, respectively), while treatment response and tumor recurrence were not. Univariate analysis showed that B symptoms (P=0.004) and Ki-67 (P=0.03) were significantly associated with progression-free survival (PFS), while MYD88 L265P showed no significant association with overall survival and PFS. Multivariate analysis showed that B symptoms were significantly associated with PFS. Our study suggests that the prognostic value of MYD88 L265P in DLBCL patients with R-CHOP requires further research.

Hepatitis C Virus-Associated Non-Hodgkin Lymphomas: Biology, Epidemiology, and Treatment

Eradication of hepatitis C virus (HCV) in indolent non-Hodgkin lymphomas (NHLs), especially in marginal zone lymphomas, determines the regression of the hematologic disorder in a significant fraction of cases. Because direct antiviral agents show an excellent profile in terms of efficacy, safety, and rapid onset of action, these drugs can be used in any clinical situation and in the presence of any comorbidities. To avoid the progression of the NHL, despite HCV eradication, antiviral therapy should be provided as soon as the viral infection is discovered; before that, the chronic antigenic stimulation determines the irreversible proliferation of neoplastic B cells.

Clinical impact of recurrently mutated genes on lymphoma diagnostics: state-of-the-art and beyond

Similar to the inherent clinical heterogeneity of most, if not all, lymphoma entities, the genetic landscape of these tumors is markedly complex in the majority of cases, with a rapidly growing list of recurrently mutated genes discovered in recent years by next-generation sequencing technology. Whilst a few genes have been implied to have diagnostic, prognostic and even predictive impact, most gene mutations still require rigorous validation in larger, preferably prospective patient series, to scrutinize their potential role in lymphoma diagnostics and patient management. In selected entities, a predominantly mutated gene is identified in almost all cases (e.g. Waldenström's macroglobulinemia/lymphoplasmacytic lymphoma and hairy-cell leukemia), while for the vast majority of lymphomas a quite diverse mutation pattern is observed, with a limited number of frequently mutated genes followed by a seemingly endless tail of genes with mutations at a low frequency. Herein, the European Expert Group on NGS-based Diagnostics in Lymphomas (EGNL) summarizes the current status of this ever-evolving field, and, based on the present evidence level, segregates mutations into the following categories: i) immediate impact on treatment decisions, ii) diagnostic impact, iii) prognostic impact, iv) potential clinical impact in the near future, or v) should only be considered for research purposes. In the coming years, coordinated efforts aiming to apply targeted next-generation sequencing in large patient series will be needed in order to elucidate if a particular gene mutation will have an immediate impact on the lymphoma classification, and ultimately aid clinical decision making.

Next Generation Sequencing Reveals Potentially Actionable Alterations in the Majority of Patients with Lymphoid Malignancies

Next generation sequencing (NGS) identifies alterations that may be potentially targetable by Food and Drug Administration (FDA) approved drugs and/or by available experimental agents that may not have otherwise been contemplated. Many targeted drugs have been developed for diverse solid cancers; a smaller number of genomically targeted drugs have been approved for lymphoid malignancies. We analyzed NGS results from 60 patients with various lymphoid malignancies and found a total of 224 alterations (median per patient = 3). Forty-nine patients (82%) had potentially actionable alterations using FDA-approved drugs and/or experimental therapies; only 11 patients (18%) had no theoretically actionable alterations. Only three patients (5%) had an alteration for which an approved drug in the disease is available (on-label); 45 patients (75%) had an alteration for which an approved drug is available in another disease (off-label). The median number of alterations per patient potentially actionable by an FDA-approved drug was 1. Interestingly, 19 of 60 patients (32%) had intermediate to high tumor mutational burden, which may predict response to certain immunotherapy agents. In conclusion, NGS identifies alterations that may be pharmacologically tractable in most patients with lymphoid malignancies, albeit with drugs that have usually been developed in the context of solid tumors. These observations merit expanded exploration in the clinical trials setting.

Molecular pathogenesis of splenic and nodal marginal zone lymphoma

Genomic studies have improved our understanding of the biological basis of splenic (SMZL) and nodal (NMZL) marginal zone lymphoma by providing a comprehensive and unbiased view of the genes/pathways that are deregulated in these diseases. Consistent with the physiological involvement of NOTCH, NF-κB, B-cell receptor and toll-like receptor signaling in mature B-cells differentiation into the marginal zone B-cells, many oncogenic mutations of genes involved in these pathways have been identified in SMZL and NMZL. Beside genetic lesions, also epigenetic and post-transcriptional modifications contribute to the deregulation of marginal zone B-cell differentiation pathways in SMZL and NMZL. This review describes the progress in understanding the molecular mechanism underlying SMZL and NMZL, including molecular and post-transcriptional modifications, and discusses how information gained from these efforts has provided new insights on potential targets of diagnostic, prognostic and therapeutic relevance in SMZL and NMZL.

NF-κB deregulation in splenic marginal zone lymphoma

Splenic marginal zone lymphoma is a rare mature B-cell malignancy involving the spleen, bone marrow and blood. Over the past years, the rapid expansion of sequencing technologies allowing the genome-wide assessment of genomic, epigenetic and transcriptional changes has revolutionized our understanding of the biological basis of splenic marginal zone lymphoma by providing a comprehensive and unbiased view of the genes/pathways that are deregulated in this disease. NF-κB is a family of transcription factors that plays critical roles in development, survival, and activation of B lymphocytes. Consistent with the physiological involvement of NF-κB signalling in proliferation and commitment of mature B-cells to the marginal zone of the spleen, many oncogenic mutations involved in constitutive activation of the NF-κB pathway were recently identified in splenic marginal zone lymphoma. This review describes the progress in understanding the mechanism of NF-κB activation in splenic marginal zone lymphoma, including molecular, epigenetic and post-transcriptional modifications of NF-κB genes and of upstream pathways, and discusses how information gained from these efforts has provided new insights on potential targets of diagnostic, prognostic and therapeutic relevance for splenic marginal zone lymphoma.

Issues in diagnosis of small B cell lymphoid neoplasms involving the bone marrow and peripheral blood. Report on the Bone Marrow Workshop of the XVIIth meeting of the European Association for Haematopathology and the Society for Hematopathology

Small B cell lymphoid neoplasms are the most common lymphoproliferative disorders involving peripheral blood (PB) and bone marrow (BM). The Bone Marrow Workshop (BMW) organized by the European Bone Marrow Working Group (EBMWG) of the European Association for Haematopathology (EAHP) during the XVIIth EAHP Meeting in Istanbul, October 2014, was dedicated to discussion of cases illustrating how the recent advances in immunophenotyping, molecular techniques and cytogenetics provide better understanding and classification of these entities. Submitted cases were grouped into following categories: (i) cases illustrating diagnostic difficulties in chronic lymphocytic leukaemia (CLL); (ii) cases of BM manifestations of small B cell lymphoid neoplasms other than CLL; (iii) transformation of small B cell lymphoid neoplasms in the BM; and (iv) multiclonality and composite lymphomas in the BM. This report summarizes presented cases and conclusions of the BMW and provides practical recommendations for classification of the BM manifestations of small B cell lymphoid neoplasms based on the current state of knowledge.

Bing-Neel Syndrome Case Report: A Previously Undocumented IgG Variant with MRI, PET/CT, and PET/MRI Imaging

Waldenstrom's macroglobulinaemia is the most commonly reported subtype of lymphoplasmacytic lymphoma (LPL); it is characterised by IgM secretion. Neurological complications are common usually as a result of hyperviscosity. In rare cases, cells can infiltrate the central nervous system; this is known as Bing-Neel syndrome. We report the case of a 57-year-old male with lymphoplasmacytic lymphoma of the IgG-subtype with neurological symptoms and the consequent finding of lymphoplasmacytoid cells in his cerebrospinal fluid as well as deposits on MRI and PET-CT imaging. This is the first report of Bing-Neel syndrome in IgG-subtype LPL. We discuss the biological and radiological markers of his disease, including PET imaging, which has been minimal in this area to date.