Genome-wide DNA profiling of marginal zone lymphomas identifies subtype-specific lesions with an impact on the clinical outcome

Section E6.1-6.6 of the American College of Medical Genetics and Genomics (ACMG) Technical Laboratory Standards: Cytogenomic studies of acquired chromosomal abnormalities in neoplastic blood, bone marrow, and lymph nodes

Cytogenomic analyses of acquired clonal chromosomal abnormalities in neoplastic blood, bone marrow, and/or lymph nodes are instrumental in the clinical management of patients with hematologic neoplasms. Cytogenetic analyses assist in the diagnosis of such disorders and can provide important prognostic information. Furthermore, cytogenetic studies can provide crucial information regarding specific genetically defined subtypes of these neoplasms that may have targeted therapies. At time of relapse, cytogenetic analysis can confirm recurrence of the original neoplasm, detect clonal disease evolution, or uncover a new unrelated neoplastic process. This section deals specifically with the technical standards applicable to cytogenomic studies of acquired clonal chromosomal abnormalities in neoplastic blood, bone marrow, and/or lymph nodes. This updated Section E6.1-6.6 supersedes the previous Section E6 in Section E: Clinical Cytogenetics of the American College of Medical Genetics and Genomics Technical Standards for Clinical Genetics Laboratories.

Predictive and prognostic molecular biomarkers in lymphomas

Recent advances in molecular diagnostics have markedly expanded our understanding of the genetic underpinnings of lymphomas and catalysed a transformation in not just how we classify lymphomas, but also how we treat, target, and monitor affected patients. Reflecting these advances, the World Health Organization Classification, International Consensus Classification, and National Comprehensive Cancer Network guidelines were recently updated to better integrate these molecular insights into clinical practice. We summarise here the molecular biomarkers of lymphomas with an emphasis on biomarkers that have well-supported prognostic and predictive utility, as well as emerging biomarkers that show promise for clinical practice. These biomarkers include: (1) diagnostic entity-defining genetic abnormalities [e.g., B-cell acute lymphoblastic leukaemia (B-ALL) with KMT2A rearrangement]; (2) molecular alterations that guide patients' prognoses (e.g., TP53 loss frequently conferring worse prognosis); (3) mutations that serve as the targets of, and often a source of acquired resistance to, small molecular inhibitors (e.g., ABL1 tyrosine kinase inhibitors for B-ALL BCR::ABL1, hindered by ABL1 kinase domain resistance mutations); (4) the growing incorporation of molecular measurable residual disease (MRD) in the management of lymphoma patients (e.g., molecular complete response and sequencing MRD-negative criteria in multiple myeloma). Altogether, our review spans the spectrum of lymphoma types, from the genetically defined subclasses of precursor B-cell lymphomas to the highly heterogeneous categories of small and large cell mature B-cell lymphomas, Hodgkin lymphomas, plasma cell neoplasms, and T/NK-cell lymphomas, and provides an expansive summary of our current understanding of their molecular pathology.

Cytogenomics of B-cell non-Hodgkin lymphomas: The "old" meets the "new"

For the routine diagnosis of haematological neoplasms an integrative approach is used considering the morphology, and the immunophenotypic, and molecular features of the tumor sample, along with clinical information. The identification and characterization of recurrent chromosomal aberrations mainly detected by conventional and molecular cytogenetics in the tumor cells has a major impact on the classification of lymphoid neoplasms. Some of the B-cell non-Hodgkin lymphomas are characterized by particular chromosomal aberrations, highlighting the relevance of conventional and molecular cytogenetic studies in their diagnosis and prognosis. In the current genomics era, next generation sequencing provides relevant information as the mutational profiles of haematological malignancies, improving their classification and also the clinical management of the patients. In addition, other new technologies have emerged recently, such as the optical genome mapping, which can overcome some of the limitations of conventional and molecular cytogenetics and may become more widely used in the cytogenetic laboratories in the upcoming years. Moreover, epigenetic alterations may complement genetic changes for a deeper understanding of the pathogenesis underlying B-cell neoplasms and a more precise risk-based patient stratification. Overall, here we describe the current state of the genomic data integrating chromosomal rearrangements, copy number alterations, and somatic variants, as well as a succinct overview of epigenomic changes, which altogether constitute a comprehensive diagnostic approach in B-cell non-Hodgkin lymphomas.

The many faces of nodal and splenic marginal zone lymphomas. A report of the 2022 EA4HP/SH lymphoma workshop

Session 3 of the lymphoma workshop of the XXI joint meeting of the European Association for Haematopathology and the Society for Hematopathology took place in Florence, Italy, on September 22, 2022. The topics of this session were splenic and nodal marginal zone lymphomas, transformation in marginal zone lymphomas, and pediatric nodal marginal zone lymphomas and their differential diagnosis as well as related entities. Forty-two cases in these categories were submitted to the workshop, including splenic lymphomas (marginal zone and diffuse red pulp lymphomas), transformed marginal zone lymphomas (splenic and nodal), nodal marginal zone lymphomas with increased TFH-cells, and pediatric nodal marginal zone lymphomas. The case review highlighted some of the principal problems in the diagnosis of marginal zone lymphomas, including the difficulties in the distinction between splenic marginal zone lymphoma, splenic diffuse red pulp lymphoma, and hairy cell leukemia variant/splenic B-cell lymphoma with prominent nucleoli which requires integration of clinical features, immunophenotype, and morphology in blood, bone marrow, and spleen; cases of marginal zone lymphoma with markedly increased TFH-cells, simulating a T-cell lymphoma, where molecular studies (clonality and mutation detection) can help to establish the final diagnosis; the criteria for transformation of marginal zone lymphomas, which are still unclear and might require the integration of morphological and molecular data; the concept of an overlapping spectrum between pediatric nodal marginal zone lymphoma and pediatric-type follicular lymphoma; and the distinction between pediatric nodal marginal zone lymphoma and "atypical" marginal zone hyperplasia, where molecular studies are mandatory to correctly classify cases.

Clinical relevance of molecular aspects in extranodal marginal zone lymphoma: a critical appraisal

Extranodal marginal zone B-cell lymphoma of the mucosa-associated lymphoid tissue (MALT lymphoma) is among the more common types of lymphoma accounting for up to 8% of newly diagnosed lymphoma cases. As opposed to other B-cell lymphomas, however, no predominant genetic hallmark has been defined in MALT lymphoma, but different localizations appear to be affected by different, sometimes distinct changes. Nonetheless, a high proportion of these genetic changes reported in MALT lymphomas dysregulate the pathways leading to NF-kB activation. t(11;18)(q21;q21)/BIRC3::MALT1 appears to be MALT lymphoma specific and is found in 24% of gastric and 40% of pulmonary MALT lymphomas. The translocation is associated with more disseminated disease in gastric MALT lymphoma and is found in a large percentage of patients whose lymphoma is unresponsive to antibiotic eradication of Helicobacter pylori. In addition to t(11;18)(q21;q21), nuclear expression of BCL10 or NF-kB appears to be highly associated with lymphoma cell survival independence of H. pylori-mediated stimulations. Antibiotic eradication, however, is the recommended therapy of choice irrespective of genetic findings, and molecular analysis is not required before initiation of therapy. The influence of genetic translocations including t(11;18)(q21;q21) on systemic therapies, however, is less clearly defined. While small series have shown no influence on the outcome for treatment with the anti-CD20 antibody rituximab (R) or treatment with cladribine (2-CdA), conflicting data have been reported for alkylating agents, especially chlorambucil and the combination of R + chlorambucil. None of other genetic changes seen in MALT lymphoma to date has discernible value in routine clinical applications, but recent data suggest that changes in TNFAIP3(A20), KMTD2 and CARD11 might be associated with response to Bruton kinase inhibitors.

Clinical features and prognosis of double primary malignant neoplasms in patients with non-hodgkin lymphoma

To investigate the clinical features, survival, and prognostic factors of patients with double primary malignant neoplasms (DPMNs) comprising non-Hodgkin lymphoma (NHL) and malignant solid tumors. Of the 2352 patients diagnosed with NHL, 105 (4.46%) patients were diagnosed with DPMNs, 42 (40.0%) had NHL first (the NHL-first group) and 63 (60.0%) had solid tumor first (the ST-first group). Females were more frequent in the ST-first group, and the interval time between the two tumors was longer. More NHLs in early stages and originating from extranodal sites were observed in the NHL-first group. Male, age ≥ 55 years at diagnosis of the first tumor, interval time <60 months, NHL diagnosed first, NHL arising from an extranodal site, DPMNs without breast cancer, and no surgery for the first primary tumor were associated with poorer overall survival (OS). Interval time <60 months and NHL diagnosed first were independent risk factors that affected the prognosis of patients with DPMNs. Therefore, careful monitoring and follow-up are especially important for these patients. 50.5% (53/105) of patients with DPMNs did not receive chemotherapy or radiotherapy prior to the diagnosis of the second tumor. We further compared the baseline characteristics of diffuse large B-cell lymphoma(DLBCL) patients with and without solid tumors, the former had a higher proportion of extranodal DLBCL, suggesting that extranodal DLBCL is more likely to develop solid tumors than nodal DLBCL.

Combined Reverse-Transcriptase Multiplex Ligation-Dependent Probe Amplification and Next-Generation Sequencing Analyses to Assign Unclassified BCL2-/BCL6- Nonrearranged Small B-Cell Lymphoid Neoplasms as Follicular or Nodal Marginal Zone Lymphoma

Distinguishing between follicular lymphoma (FL) and nodal marginal zone lymphoma (NMZL) can be difficult when morphologic and phenotypic features are unusual and characteristic cytogenetic rearrangements are absent. We evaluated the diagnostic contribution of ancillary techniques-including fluorescence in situ hybridization (FISH)-detected 1p36 deletion; reverse-transcriptase, multiplex, ligation-dependent probe amplification (RT-MLPA); and next-generation sequencing (NGS)-for tumors that remain unclassified according to standard criteria. After review, 50 CD5-negative small B-cell lymphoid neoplasms without BCL2 and BCL6 FISH rearrangements were diagnosed as FLs (n = 27), NMZLs (n = 5), or unclassified (n = 18) based on the 2016 World Health Organization Classification of Tumours of Haematopoietic and Lymphoid Tissues. FISH helped identify the 1p36 deletion in 3 FLs and 1 unclassified tumor. Most classified FLs had an RT-MLPA germinal center B-cell (GCB) signature (93%) or were noncontributive (7%). Classified NMZLs had an RT-MLPA activated B-cell signature (20%), had an unassigned signature (40%), or were noncontributive (40%). Among unclassified tumors, the RT-MLPA GCB signature was associated with mutations most commonly found in FLs (CREBBP, EZH2, STAT6, and/or TNFRSF14) (90%). An RT-MLPA-detected GCB signature and/or NGS-detected gene mutations were considered as FL identifiers for 13 tumors. An activated B-cell signature or NOTCH2 mutation supported NMZL diagnosis in 3 tumors. Combining the RT-MLPA and NGS findings successfully discriminated 89% of unclassified tumors in favor of one or the other diagnosis. NGS-detected mutations may be of therapeutic interest. Herein, we detected 3 EZH2 and 8 CREBBP mutations that might be eligible for targeted therapies.

Genomic profiling for clinical decision making in lymphoid neoplasms

With the introduction of large-scale molecular profiling methods and high-throughput sequencing technologies, the genomic features of most lymphoid neoplasms have been characterized at an unprecedented scale. Although the principles for the classification and diagnosis of these disorders, founded on a multidimensional definition of disease entities, have been consolidated over the past 25 years, novel genomic data have markedly enhanced our understanding of lymphomagenesis and enriched the description of disease entities at the molecular level. Yet, the current diagnosis of lymphoid tumors is largely based on morphological assessment and immunophenotyping, with only few entities being defined by genomic criteria. This paper, which accompanies the International Consensus Classification of mature lymphoid neoplasms, will address how established assays and newly developed technologies for molecular testing already complement clinical diagnoses and provide a novel lens on disease classification. More specifically, their contributions to diagnosis refinement, risk stratification, and therapy prediction will be considered for the main categories of lymphoid neoplasms. The potential of whole-genome sequencing, circulating tumor DNA analyses, single-cell analyses, and epigenetic profiling will be discussed because these will likely become important future tools for implementing precision medicine approaches in clinical decision making for patients with lymphoid malignancies.

The 5th edition of the World Health Organization Classification of Haematolymphoid Tumours: Lymphoid Neoplasms

We herein present an overview of the upcoming 5^th edition of the World Health Organization Classification of Haematolymphoid Tumours focussing on lymphoid neoplasms. Myeloid and histiocytic neoplasms will be presented in a separate accompanying article. Besides listing the entities of the classification, we highlight and explain changes from the revised 4^th edition. These include reorganization of entities by a hierarchical system as is adopted throughout the 5^th edition of the WHO classification of tumours of all organ systems, modification of nomenclature for some entities, revision of diagnostic criteria or subtypes, deletion of certain entities, and introduction of new entities, as well as inclusion of tumour-like lesions, mesenchymal lesions specific to lymph node and spleen, and germline predisposition syndromes associated with the lymphoid neoplasms.

Genomic landscape of Epstein-Barr virus-positive extranodal marginal zone lymphomas of mucosa-associated lymphoid tissue

Epstein-Barr virus (EBV)-positive extranodal marginal zone lymphomas of mucosa-associated lymphoid tissue (MALT lymphomas) were initially described in solid organ transplant recipients, and, more recently, in other immunodeficiency settings. The overall prevalence of EBV-positive MALT lymphomas has not been established, and little is known with respect to their genomic characteristics. Eight EBV-positive MALT lymphomas were identified, including 1 case found after screening a series of 88 consecutive MALT lymphomas with EBER in situ hybridization (1%). The genomic landscape was assessed in 7 of the 8 cases with a targeted high throughput sequencing panel and array comparative genomic hybridization. Results were compared to published data for MALT lymphomas. Of the 8 cases, 6 occurred post-transplant, 1 in the setting of primary immunodeficiency, and 1 case was age-related. Single pathogenic/likely pathogenic mutations were identified in 4 of 7 cases, including mutations in IRF8, BRAF, TNFAIP3, and SMARCA4. Other than TNFAIP3, these genes are mutated in <3% of EBV-negative MALT lymphomas. Copy number abnormalities were identified in 6 of 7 cases with a median of 6 gains and 2 losses per case, including 4 cases with gains in regions encompassing several IRF family or interacting genes (IRF2BP2, IRF2, and IRF4). There was no evidence of trisomies of chromosomes 3 or 18. In summary, EBV-positive MALT lymphomas are rare and, like other MALT lymphomas, are usually genetically non-complex. Conversely, while EBV-negative MALT lymphomas typically show mutational abnormalities in the NF-κB pathway, other than the 1 TNFAIP3-mutated case, no other NF-κB pathway mutations were identified in the EBV-positive cases. EBV-positive MALT lymphomas often have either mutations or copy number abnormalities in IRF family or interacting genes, suggesting that this pathway may play a role in these lymphomas.

Histological Transformation and Clonal Relationship of Subcutaneous Marginal Zone B-Cell Lymphoma and Diffuse Large B-Cell Lymphoma

ABSTRACT

Histological transformation (HT) is an exceptionally uncommon and poorly understood event where a low-grade or indolent B-cell lymphoma transforms into a more aggressive entity, typically diffuse large B-cell lymphoma (DLBCL). The pathogenesis is unclear; however, HT is associated with a worse prognosis. This article reports a unique case of marginal zone lymphoma (MZL) limited to skin/subcutis (confirmed with PET-CT) that subsequently developed DLBCL, followed by nodal MZL. We explored phenotypic, molecular genetic, and cytogenetic findings in subcutaneous MZL with HT to DLBCL and subsequent progression to systemic MZL. Shared clonal peaks between the tumors were demonstrated through immunoglobulin heavy chain PCR, and genomic microarray analysis revealed both unique genomic abnormalities and shared regions of copy-neutral loss of heterozygosity in all specimens. BCL-2 expression was present in the original subcutaneous MZL, lost on conversion to Primary cutaneous diffuse large B cell lymphoma (PCDLBCL)-NOS, and regained during subsequent transformation to systemic MZL. The PCDLBCL-NOS did not demonstrate FISH rearrangements for MYC, BCL2, and BCL6. Here, we describe the histologic, immunophenotypic, and cytogenetic abnormalities of the clonally related transformation of subcutaneous MZL, PCDLBCL-NOS, and eventual systemic MZL. The predominantly subcutaneous presentation of MZL may be associated with a more aggressive outcome and raises consideration for careful evaluation of patients who present with this pattern.

Identification of a Cancer-Predisposing Germline POT1 p.Ile49Metfs*7 Variant by Targeted Sequencing of a Splenic Marginal Zone Lymphoma

Germline disruptive variants in Protection of Telomeres 1 (POT1) predispose to a wide variety of cancers, including melanoma, chronic lymphocytic leukemia (CLL), Hodgkin lymphoma, myeloproliferative neoplasms, and glioma. We report the first case of splenic marginal zone lymphoma (SMZL) arising in a patient with a germline POT1 variant: a 65-year-old male with an extensive history of cancer, including melanoma and papillary thyroid carcinoma, who presented with circulating atypical lymphocytosis. Bone marrow biopsy revealed 20% involvement by a CD5−CD10− B-cell lymphoma that was difficult to classify. During the clinical workup of his low-grade lymphoma, targeted next-generation sequencing (NGS) identified POT1 p.I49Mfs*7 (NM_015450:c. 147delT) at a variant allele frequency (VAF) of 51%. NGS of skin fibroblasts confirmed the POT1 variant was germline. This likely pathogenic POT1 loss-of-function variant has only been reported once before as a germline variant in a patient with glioma and likely represents one of the most deleterious germline POT1 variants ever linked to familial cancer. The spectrum of cancers associated with germline pathogenic POT1 variants (i.e., autosomal dominant POT1 tumor predisposition syndrome) should potentially be expanded to include SMZL, a disease often associated with the loss of chromosome 7q: the location of the POT1 genetic locus (7q31.33).

Genetic and phenotypic attributes of splenic marginal zone lymphoma

Splenic marginal zone B-cell lymphoma (SMZL) is a heterogeneous clinico-biological entity. The clinical course is variable, multiple genes are mutated with no unifying mechanism, and essential regulatory pathways and surrounding microenvironments are diverse. We sought to clarify the heterogeneity of SMZL by resolving different subgroups and their underlying genomic abnormalities, pathway signatures, and microenvironment compositions to uncover biomarkers and therapeutic vulnerabilities. We studied 303 SMZL spleen samples collected through the IELSG46 multicenter international study (NCT02945319) by using a multiplatform approach. We carried out genetic and phenotypic analyses, defined self-organized signatures, validated the findings in independent primary tumor metadata and in genetically modified mouse models, and determined correlations with outcome data. We identified 2 prominent genetic clusters in SMZL, termed NNK (58% of cases, harboring NF-κB, NOTCH, and KLF2 modules) and DMT (32% of cases, with DNA-damage response, MAPK, and TLR modules). Genetic aberrations in multiple genes as well as cytogenetic and immunogenetic features distinguished NNK- from DMT-SMZLs. These genetic clusters not only have distinct underpinning biology, as judged by differences in gene-expression signatures, but also different outcomes, with inferior survival in NNK-SMZLs. Digital cytometry and in situ profiling segregated 2 basic types of SMZL immune microenvironments termed immune-suppressive SMZL (50% of cases, associated with inflammatory cells and immune checkpoint activation) and immune-silent SMZL (50% of cases, associated with an immune-excluded phenotype) with distinct mutational and clinical connotations. In summary, we propose a nosology of SMZL that can implement its classification and also aid in the development of rationally targeted treatments.

Recent Advances in the Genetic of MALT Lymphomas

Simple Summary

Mucosa-associated lymphoid tissue (MALT) lymphoma is the most common subtype of marginal zone lymphomas. These B-cell neoplasms may arise from many organs and usually have an indolent behavior. Recurrent chromosomal translocations and cytogenetic alterations are well characterized, some of them being associated to specific sites. Through next-generation sequencing technologies, the mutational landscape of MALT lymphomas has been explored and available data to date show that there are considerable variations in the incidence and spectrum of mutations among MALT lymphoma of different sites. Interestingly, most of these mutations affect several common pathways and some of them are potentially targetable. Gene expression profile and epigenetic studies have also added new information, potentially useful for diagnosis and treatment. This article provides a comprehensive review of the genetic landscape in MALT lymphomas.

Abstract

Mucosa-associated lymphoid tissue (MALT) lymphomas are a diverse group of lymphoid neoplasms with B-cell origin, occurring in adult patients and usually having an indolent clinical behavior. These lymphomas may arise in different anatomic locations, sharing many clinicopathological characteristics, but also having substantial variances in the aetiology and genetic alterations. Chromosomal translocations are recurrent in MALT lymphomas with different prevalence among different sites, being the 4 most common: t(11;18)(q21;q21), t(1;14)(p22;q32), t(14;18)(q32;q21), and t(3;14)(p14.1;q32). Several chromosomal numerical abnormalities have also been described, but probably represent secondary genetic events. The mutational landscape of MALT lymphomas is wide, and the most frequent mutations are: TNFAIP3, CREBBP, KMT2C, TET2, SPEN, KMT2D, LRP1B, PRDM1, EP300, TNFRSF14, NOTCH1/NOTCH2, and B2M, but many other genes may be involved. Similar to chromosomal translocations, certain mutations are enriched in specific lymphoma types. In the same line, variation in immunoglobulin gene usage is recognized among MALT lymphoma of different anatomic locations. In the last decade, several studies have analyzed the role of microRNA, transcriptomics and epigenetic alterations, further improving our knowledge about the pathogenic mechanisms in MALT lymphoma development. All these advances open the possibility of targeted directed treatment and push forward the concept of precision medicine in MALT lymphomas.

CD5-Negative, CD10-Negative Low-Grade B-Cell Lymphoproliferative Disorders of the Spleen

CD5-negative, CD10-negative low-grade B-cell lymphoproliferative disorders (CD5-CD10-LPD) of the spleen comprise a fascinating group of indolent, neoplastic, mature B-cell proliferations that are essential to accurately identify but can be difficult to diagnose. They comprise the majority of B-cell LPDs primary to the spleen, commonly presenting with splenomegaly and co-involvement of peripheral blood and bone marrow, but with little to no involvement of lymph nodes. Splenic marginal zone lymphoma is one of the prototypical, best studied, and most frequently encountered CD5-CD10-LPD of the spleen and typically involves white pulp. In contrast, hairy cell leukemia, another well-studied CD5-CD10-LPD of the spleen, involves red pulp, as do the two less common entities comprising so-called splenic B-cell lymphoma/leukemia unclassifiable: splenic diffuse red pulp small B-cell lymphoma and hairy cell leukemia variant. Although not always encountered in the spleen, lymphoplasmacytic lymphoma, a B-cell lymphoproliferative disorder consisting of a dual population of both clonal B-cells and plasma cells and the frequent presence of the MYD88 L265P mutation, is another CD5-CD10-LPD that can be seen in the spleen. Distinction of these different entities is possible through careful evaluation of morphologic, immunophenotypic, cytogenetic, and molecular features, as well as peripheral blood and bone marrow specimens. A firm understanding of this group of low-grade B-cell lymphoproliferative disorders is necessary for accurate diagnosis leading to optimal patient management.

DNA Methylation-Based Classification of Small B-Cell Lymphomas: A Proof-of-Principle Study

Although most small B-cell lymphomas (SBCLs) can be diagnosed using routine methods, challenges exist. For example, marginal zone lymphomas (MZLs) can be difficult to rule-in, in large part because no widely-used, sensitive, and specific biomarker is available for the marginal zone cell of origin. In this study, it was hypothesized that DNA methylation array profiling can assist with the classification of SBCLs, including MZLs. Extramedullary SBCLs, including challenging cases, were reviewed internally for pathology consensus and profiled. By combining the resulting array data set with data sets from other groups, a set of 26 informative probes was selected and used to train machine learning models to classify 4 common SBCLs: chronic lymphocytic leukemia/small lymphocytic lymphoma, follicular lymphoma, mantle cell lymphoma, and MZL. Prediction probability cutoff was used to separate classifiable from unclassifiable cases, and show that the trained model was able to classify 95% of independent test cases (n = 264/279). The concordance between model predictions and pathology diagnoses was 99.6% (n = 262/263) among classifiable test cases. One validation reference test case was reclassified based on model prediction. The model was also used to predict the diagnoses of two challenging SBCLs. Although the differential examined and data on difficult cases are limited, these results support accurate methylation-based classification of SBCLs. Furthermore, high specificities of predictions suggest that methylation signatures can be used to rule-in MZLs.

CD5 expression in marginal zone lymphoma predicts differential response to rituximab or bendamustine/rituximab

We examined outcomes of 244 patients with marginal zone lymphoma (MZL) diagnosed in 2010-2020, of which 25 (10%) expressed CD5. CD5 expression was present in 22% of splenic, 8% of nodal, and 5% of extranodal MZL, and showed frequent blood/bone marrow involvement, elevated lactate dehydrogenase, and TP53 deletions. CD5 expression was not associated with progression-free or overall survival, but it conferred a significantly higher risk of histologic transformation (22% versus 4% at 5 years, p = 0.002). Among patients receiving first-line rituximab monotherapy, CD5 expression was associated with lower response rate (30% versus 77%, p = 0.006), PFS (25% versus 45% at 3 years, p = 0.003) and OS (44% versus 77%, p = 0.010), whereas CD5 status did not significantly affect outcomes of patients receiving bendamustine with rituximab (P for interaction = 0.012 for progression-free survival). CD5-positive MZL may have a propensity to leukemic dissemination, histologic transformation, and may derive benefit from first-line bendamustine/rituximab rather than rituximab alone.

Recent advances upper gastrointestinal lymphomas: molecular updates and diagnostic implications

Approximately one-third of extranodal non-Hodgkin lymphomas involve the gastrointestinal (GI) tract, with the vast majority being diagnosed in the stomach, duodenum, or proximal small intestine. A few entities, especially diffuse large B-cell lymphoma and extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue, represent the majority of cases. In addition, there are diseases specific to or characteristic of the GI tract, and any type of systemic lymphoma can present in or disseminate to these organs. The recent advances in the genetic and molecular characterisation of lymphoid neoplasms have translated into notable changes in the classification of primary GI T-cell neoplasms and the recommended diagnostic approach to aggressive B-cell tumours. In many instances, diagnoses rely on morphology and immunophenotype, but there is an increasing need to incorporate molecular genetic markers. Moreover, it is also important to take into consideration the endoscopic and clinical presentations. This review gives an update on the most recent developments in the pathology and molecular pathology of upper GI lymphoproliferative diseases.

Pathogenetic Mechanisms Implicated in Sjögren's Syndrome Lymphomagenesis: A Review of the Literature

Sjögren's Syndrome (SS) is a chronic autoimmune disorder characterized by focal mononuclear cell infiltrates that surround the ducts of the exocrine glands, impairing the function of their secretory units. Compared to other autoimmune disorders, SS is associated with a notably high incidence of non-Hodgkin lymphoma (NHL) and more frequently mucosa associated lymphoid tissue (MALT) lymphoma, leading to increased morbidity and mortality rates. High risk features of lymphoma development include systemic extraepithelial manifestations, low serum levels of complement component C4 and mixed type II cryoglobulinemia. The discrimination between reactive and neoplastic lymphoepithelial lesion (LEL) is challenging, probably reflecting a continuum in the evolution from purely inflammatory lymphoid infiltration to the clonal neoplastic evolution. Early lesions display a predominance of activated T cells, while B cells prevail in severe histologic lesions. This strong B cell infiltration is not only a morphologic phenomenon, but it is also progressively associated with the presence of ectopic germinal centers (GCs). Ectopic formation of GCs in SS represents a complex process regulated by an array of cytokines, adhesion molecules and chemokines. Chronic antigenic stimulation is the major driver of specific B cell proliferation and increases the frequency of their transformation in the ectopic GCs and marginal zone (MZ) equivalents. B cells expressing cell surface rheumatoid factor (RF) are frequently detected in the salivary glands, suggesting that clonal expansion might arise from antigen selection of RF-expressing B cells. Abnormal stimulation and incomplete control mechanisms within ectopic lymphoid structures predispose RF MZ like cells to lymphoma development. Immunoglobulin recombination, somatic mutation and isotype switching during B cell development are events that may increase the translocation of oncogenes to immunoglobulin loci or tumor suppressor gene inactivation, leading to monoclonal B cell proliferation and lymphoma development. Concerning chronic antigenic stimulation, conclusive data is so far lacking. However immune complexes containing DNA or RNA are the most likely candidates. Whether additional molecular oncogenic events contribute to the malignant overgrowth remains to be proved.

Preserving immune homeostasis with A20

A20/TNFAIP3 is a TNF induced gene that plays a profound role in preserving cellular and organismal homeostasis (Lee, et al., 2000; Opipari etal., 1990). This protein has been linked to multiple human diseases via genetic, epigenetic, and an emerging series of patients with mono-allelic coding mutations. Diverse cellular functions of this pleiotropically expressed protein include immune-suppressive, anti-inflammatory, and cell protective functions. The A20 protein regulates ubiquitin dependent cell signals; however, the biochemical mechanisms by which it performs these functions is surprisingly complex. Deciphering these cellular and biochemical facets of A20 dependent biology should greatly improve our understanding of murine and human disease pathophysiology as well as unveil new mechanisms of cell and tissue biology.

Targeting pathogenic mechanisms in marginal zone lymphoma: from concepts and beyond

Marginal zone lymphoma (MZL) represents a group of three distinct though overlapping lymphoid malignancies that includes extranodal, nodal and splenic marginal lymphoma. MZL patients usually present an indolent clinical course, although the disease remains largely incurable, save early stage disease that might be irradiated. Therapeutic advances have been limited due to the small patient population, and have largely been adapted from other indolent lymphomas. Here, we discuss the numerous targets and pathways which may offer the prospect of directly inhibiting the mechanisms identified promoting and sustaining marginal zone lymphomagenesis. In particular, we focus on the agents that may have at least a theoretical application in the disease. Various dysregulated pathways converge to produce an overarching stimulation of nuclear factor κB (NF-κB) and the MYD88-IRAK4 axis, which can be thus leveraged or targeting B-cell receptor signaling through BTK inhibitors (such as ibrutinib, zanubrutinib, acalabrutinib) and PI3K inhibitors (such as idelalisib, copanlisib, duvelisib umbralisib) or via more novel agents in development such as MALT1 inhibitors, SMAC mimetics, NIK inhibitors, IRAK4 or MYD88 inhibitors. NOTCH signaling is also crucial for marginal zone cells, but no clinical data are available with NOTCH inhibitors such as the γ-secretase inhibitor PF-03084014 or the NICD inhibitor CB-103. The hypermethylation phenotype, the overexpression of the PRC2-complex or the presence of TET2 mutations reported in MZL subsets make epigenetic agents (demethylating agents, EZH2 inhibitors, HDAC inhibitors) also potential therapeutic tools for MZL patients.

B-cell neoplasms and Hodgkin lymphoma in the spleen

B-cell lymphoma of spleen may be primary (most commonly splenic diffuse large B-cell lymphoma) or secondary (typically low-grade non-Hodgkin lymphoma). Depending on the specific lymphoma subtype, there may be a predominantly white pulp pattern of involvement, a predominantly red pulp pattern or a focal nodular pattern. Splenectomy is the ideal specimen for a multiparametric integrative diagnosis of splenic lymphoma, as it allows for a combined study of morphology, immunohistology, flow cytometry, cytogenetics, and molecular genetic techniques. This review article describes the clinicopathologic characteristics of all the relevant B-cell neoplasms that may be encountered in a splenic biopsy or a splenectomy specimen.

Discovery of Novel Recurrent Mutations and Clinically Meaningful Subgroups in Nodal Marginal Zone Lymphoma

Nodal marginal zone lymphoma (NMZL) is a rare B-cell neoplasm, the genetic and transcriptomic landscape of which are unclear. Using high-throughput sequencing for whole-exome and transcriptome, we investigated the genetic characteristics of NMZL in a discovery cohort (n = 8) and validated their features in an extended cohort (n = 30). Novel mutations in NFKBIE and ITPR2 were found in 7.9% (3/38) and 13.9% (5/36), respectively, suggesting roles for the NF-κB pathway and B-cell-receptor-mediated calcium signaling pathway in the pathogenesis of NMZL. RNA-seq showed that NMZLs were characterized by an aberrant marginal zone differentiation, associated with an altered IRF4-NOTCH2 axis and the enrichment of various oncogenic pathways. Based on gene expression profile, two subgroups were identified. Compared with subgroup 1, subgroup 2 showed the following: the significant enrichment of cell cycle-associated and MYC-signaling pathways, a more diverse repertoire of upstream regulators, and higher Ki-67 proliferation indices. We designated two subgroups according to Ki-67 labeling, and subgroup 2 was significantly associated with a shorter progression-free survival (p = 0.014), a greater proportion of large cells (p = 0.009), and higher MYC expression (p = 0.026). We suggest that NMZL has unique features and, in this study, we provide information as to the heterogeneity of this enigmatic entity.

CREBBP and STAT6 co-mutation and 16p13 and 1p36 loss define the t(14;18)-negative diffuse variant of follicular lymphoma

The diffuse variant of follicular lymphoma (dFL) is a rare variant of FL lacking t(14;18) that was first described in 2009. In this study, we use a comprehensive approach to define unifying pathologic and genetic features through gold-standard pathologic review, FISH, SNP-microarray, and next-generation sequencing of 16 cases of dFL. We found unique morphologic features, including interstitial sclerosis, microfollicle formation, and rounded nuclear cytology, confirmed absence of t(14;18) and recurrent deletion of 1p36, and showed a novel association with deletion/CN-LOH of 16p13 (inclusive of CREBBP, CIITA, and SOCS1). Mutational profiling demonstrated near-uniform mutations in CREBBP and STAT6, with clonal dominance of CREBBP, among other mutations typical of germinal-center B-cell lymphomas. Frequent CREBBP and CIITA codeletion/mutation suggested a mechanism for immune evasion, while subclonal STAT6 activating mutations with concurrent SOCS1 loss suggested a mechanism of BCL-xL/BCL2L1 upregulation in the absence of BCL2 rearrangements. A review of the literature showed significant enrichment for 16p13 and 1p36 loss/CN-LOH, STAT6 mutation, and CREBBP and STAT6 comutation in dFL, as compared with conventional FL. With this comprehensive approach, our study demonstrates confirmatory and novel genetic associations that can aid in the diagnosis and subclassification of this rare type of lymphoma.

Marginal zone B-cell lymphoma: lessons from Western and Eastern diagnostic approaches

Marginal zone B-cell lymphomas (MZLs) are a group of clinically indolent B-cell lymphomas postulated to derive from memory B lymphocytes in the 'marginal zone' of secondary lymphoid tissue. Today, MZL is recognised as a nosological umbrella term encompassing distinct entities with some shared phenotypic and genotypic features, including extranodal marginal zone B-cell lymphoma (EMZL) or mucosa-associated lymphoid tissue (MALT) lymphoma, splenic MZL, and nodal MZL, accounting for approximately 70%, 20%, and 10% of MZLs, respectively. These lymphomas share some phenotypic and genotypic features and have some variants and related provisional diseases, but are different in regards to their clinical and molecular characteristics. In addition, they are frequently associated with chronic antigenic stimulation represented either by infectious agents, particularly bacteria and viruses, or autoimmune diseases as exemplified by Sjögren syndrome, Hashimoto thyroiditis, and newly recognised IgG4-related disease. Furthermore, several chromosomal translocations have been identified in EMZL. In this review, we will focus on the updated histopathological criteria and the main problems with differential diagnoses in order to aid the diagnostic approach in our routine practice.

Contemporary management of nodal and primary splenic marginal zone lymphoma

Introduction: Marginal zone lymphoma (MZL) accounts for approximately 10% of all cases of non-Hodgkin lymphoma and includes 3 clinically distinct subtypes: extranodal (MALT), splenic (SMZL), and nodal (NMZL). Though commonly grouped in trials of iNHL the clinical behavior, molecular features, and response to therapy of MZL is distinct from other iNHL subtypes and varies among MZL subtypes.Areas covered: This review focuses on the contemporary management of NMZL and SMZL. Treatment with monoclonal antibodies, chemoimmunotherapy, BTK inhibitors, PI3K/mTOR inhibitors, Bcl2 inhibitors, lenalidomide, and CAR-T cell therapy will be covered.Expert opinion: In the era of targeted medicine, the need to develop MZL specific clinicogenetic models with prognostic and predictive value in both the frontline and relapsed/refractory setting is becoming increasingly apparent. Due to the relative rarity of each MZL subtype, the use of novel trial design with correlative studies is imperative to advance the field.

Recent Advances in the Targeting of Epigenetic Regulators in B-Cell Non-Hodgkin Lymphoma

In the last 10 years, major advances have been made in the diagnosis and development of selective therapies for several blood cancers, including B-cell non-Hodgkin lymphoma (B-NHL), a heterogeneous group of malignancies arising from the mature B lymphocyte compartment. However, most of these entities remain incurable and current treatments are associated with variable efficacy, several adverse events, and frequent relapses. Thus, new diagnostic paradigms and novel therapeutic options are required to improve the prognosis of patients with B-NHL. With the recent deciphering of the mutational landscapes of B-cell disorders by high-throughput sequencing, it came out that different epigenetic deregulations might drive and/or promote B lymphomagenesis. Consistently, over the last decade, numerous epigenetic drugs (or epidrugs) have emerged in the clinical management of B-NHL patients. In this review, we will present an overview of the most relevant epidrugs tested and/or used so far for the treatment of different subtypes of B-NHL, from first-generation epigenetic therapies like histone acetyl transferases (HDACs) or DNA-methyl transferases (DNMTs) inhibitors to new agents showing selectivity for proteins that are mutated, translocated, and/or overexpressed in these diseases, including EZH2, BET, and PRMT. We will dissect the mechanisms of action of these epigenetic inhibitors, as well as the molecular processes underlying their lack of efficacy in refractory patients. This review will also provide a summary of the latest strategies being employed in preclinical and clinical settings, and will point out the most promising lines of investigation in the field.

Actualités dans les lymphomes à petites cellules non folliculaires

Non-follicular small cell lymphomas include several entities whose clinical and pathological descriptions have been refined in the last 20 years. MALT lymphoma, developed at the expense of lymphoid tissue associated with the mucosa, is usually localized to a given organ, but can also disseminate. Some patients with MALT lymphoma can be treated by eradicating the associated infectious agent, whereas local treatment should be preferred for other cases ; disseminated forms and relapsed patients are eligible for anti-CD20 antibodies associated with cytotoxic agents. Patients with mantle cell lymphoma have benefited from many advances, including the use of cytarabine and bendamustine, anti-CD20 antibodies, intensive treatments (autograft) and recently targeted therapy (ibrutinib, inhibitor or the Bruton tyrosine kinase). Patients with splenic nodal marginal zone lymphomas should be evaluated for different options, of which immunochemotherapy remains important. For all these entities, the implementation of treatments may be delayed by several years for certain groups of patients. Although considered as incurable, the prognosis of these pathologies has improved significantly and the majority of patients will be able to live for many years with often treatment-free intervals.

The NOTCH Pathway and Its Mutations in Mature B Cell Malignancies

The systematic application of next-generation sequencing to large cohorts of oncologic samples has opened a Pandora's box full of known and novel genetic lesions implicated in different steps of cancer development and progression. Narrowing down to B cell malignancies, many previously unrecognized genes emerged as recurrently mutated. The challenge now is to determine how the mutation in a given gene affects the biology of the disease, paving the way to functional genomics studies. Mutations in NOTCH family members are shared by several disorders of the B series, even if with variable frequencies and mutational patterns. In silico predictions, revealed that mutations occurring in NOTCH receptors, despite being qualitatively different, may have similar effects on protein processing, ultimately leading to enhanced pathway activation. The discovery of mutations occurring also in downstream players, either potentiating positive signals or compromising negative regulators, indicates that multiple mechanisms in neoplastic B cells concur to activate NOTCH pathway. These findings are supported by results obtained in chronic lymphocytic leukemia and splenic marginal zone B cell lymphoma where deregulation of NOTCH signaling has been functionally characterized. The emerging picture confirms that NOTCH signaling is finely tuned in cell- and microenvironment-dependent ways. In B cell malignancies, it contributes to the regulation of proliferation, survival and migration. However, deeper biological studies are needed to pinpoint the contribution of NOTCH in the hierarchy of events driving B cells transformation, keeping in mind its role in normal B cells development. Because of its relevance in leukemia and lymphoma biology, the NOTCH pathway might represent an appealing therapeutic target: the next few years will tell whether this potential will be fulfilled.

Splenic B-Cell Lymphomas with Diffuse Cyclin D1 Protein Expression and Increased Prolymphocytic Cells: A Previously Unrecognized Diagnostic Pitfall

Prolymphocytic transformation is a concept usually applied in the context of chronic lymphocytic leukemia/small lymphocytic lymphoma to describe the presence of a high percentage of prolymphocytes in peripheral blood (usually more than 55%). Prolymphocytic transformation has also been reported in mantle cell lymphoma (MCL) but only rarely in splenic marginal zone lymphoma (SMZL). We present two splenic B-cell lymphomas presenting in the leukemic phase and with increased prolymphocytes, both classified as SMZL with prolymphocytic transformation. One case clinically simulated B-prolymphocytic leukemia (B-PLL). Both lymphomas were very unusual because the tumor cells diffusely and strongly expressed cyclin D1 despite lacking the t(11; 14)(q13; q32) as detected by several approaches including next-generation sequencing, fluorescence in situ hybridization using CCND1 break apart probe and fusion probes for t(11; 14)(q13; q32), and conventional karyotyping. These cases therefore simulated prolymphocytic variants of MCL. The incidence of this phenomenon is unknown, and awareness of this potential alternate protein expression pattern is important in order to avoid diagnostic errors.

PD1hi cells associate with clusters of proliferating B-cells in marginal zone lymphoma

Background

Abnormally sustained immune reactions drive B-cell proliferation in some cases of marginal zone lymphoma but the CD4⁺ T-cell subsets, which are likely to contribute to the B-cell responses in the tumour microenvironment, are not well characterised and neither has the spatial distribution of the different subsets in involved lymph nodes been investigated.

Methods

Employing a workflow of multiplex semi-automated immunohistochemistry combined with image processing we investigated association between infiltrating T-cells and proliferating lymphoma B-cells.

Results

Both total numbers of activating follicular helper (Tfh) cells (defined by high expression of PD1) and suppressive regulatory (Treg) T-cells (defined by FOXP3⁺ expression) and the Tfh:Treg ratio, assessed over relatively large areas of tissue, varied among cases of marginal zone lymphoma. We determined spatial distribution and demonstrated that PD1^hi cells showed significantly more clustering than did FOXP3⁺. To investigate the association of infiltrating T-cells with lymphoma B-cells we employed Pearson correlation and Morisita-Horn index, statistical measures of interaction. We demonstrated that PD1^hi cells were associated with proliferating B-cells and confirmed this by nearest neighbour analysis.

Conclusions

The unexpected architectural complexity of T-cell infiltration in marginal zone lymphoma, revealed in this study, further supports a key role for Tfh cells in driving proliferation of lymphoma B-cells. We demonstrate the feasibility of digital analysis of spatial architecture of T-cells within marginal zone lymphoma and future studies will be needed to determine the clinical importance of these observations.

Deciphering splenic marginal zone lymphoma pathogenesis: the proposed role of microRNA

Splenic marginal zone lymphoma (SMZL) is a malignancy of mature B-cells that primarily involves the spleen, but can affect peripheral organs as well. Even though SMZL is overall considered an indolent malignancy, the majority of cases will eventually progress to be more aggressive. In recent years, the gene expression profile of SMZL has been characterized in an effort to identify: 1) the etiology of SMZL, 2) biological consequences of SMZL, and 3) putative therapeutic targets. However, due to the vast heterogeneity of the malignancy, no conclusive target(s) have been deciphered. However, the role of miRNA in SMZL, much as it has in chronic lymphocytic leukemia, may serve as a guiding light. As a result, we review the comprehensive expression profiling in SMZL to-date, as well as describe the miRNA (and potential mechanistic roles) that may play a role in SMZL transformation, particularly within the 7q region.

Recent advances in understanding the biology of marginal zone lymphoma

There are three different marginal zone lymphomas (MZLs): the extranodal MZL of mucosa-associated lymphoid tissue (MALT) type (MALT lymphoma), the splenic MZL, and the nodal MZL. The three MZLs share common lesions and deregulated pathways but also present specific alterations that can be used for their differential diagnosis. Although trisomies of chromosomes 3 and 18, deletions at 6q23, deregulation of nuclear factor kappa B, and chromatin remodeling genes are frequent events in all of them, the three MZLs differ in the presence of recurrent translocations, mutations affecting the NOTCH pathway, and the transcription factor Kruppel like factor 2 ( KLF2) or the receptor-type protein tyrosine phosphatase delta ( PTPRD). Since a better understanding of the molecular events underlying each subtype may have practical relevance, this review summarizes the most recent and main advances in our understanding of the genetics and biology of MZLs.

Management of relapsed/refractory marginal zone lymphoma: focus on ibrutinib

Marginal zone lymphomas (MZLs) consist of a diverse family of malignancies, which are derived from B-cells. The disease subtypes are recognized extranodal, nodal, and splenic MZLs. The disease characteristics, clinical course, and treatment vary considerably based on the site of involvement. In 2017, the US Food and Drug Administration approved ibrutinib, a first in class Bruton’s tyrosine kinase inhibitor that revolutionized the care of chronic lymphocytic leukemia patients; for, the treatment of relapsed/refractory MZL based on pivotal open-label Phase II trial demonstrated an overall response rate of 48%, with a complete response rate of 3%, median progression-free survival of 14.2 months, and median overall survival not yet reached at a median follow-up of 19.4 months. In this review, we aim to summarize the current conundrums in the management of MZL and the evolving role of ibrutinib in the treatment of MZL.

High-throughput sequencing of nodal marginal zone lymphomas identifies recurrent BRAF mutations

Nodal marginal zone lymphoma (NMZL) is a rare small B-cell lymphoma lacking disease-defining phenotype and precise diagnostic markers. To better understand the mutational landscape of NMZL, particularly in comparison to other nodal small B-cell lymphomas, we performed whole-exome sequencing, targeted high-throughput sequencing, and array-comparative genomic hybridization on a retrospective series. Our study identified for the first time recurrent, diagnostically useful, and potentially therapeutically relevant BRAF mutations in NMZL. Sets of somatic mutations that could help to discriminate NMZL from other closely related small B-cell lymphomas were uncovered and tested on unclassifiable small B-cell lymphoma cases, in which clinical, morphological, and phenotypical features were equivocal. Application of targeted gene panel sequencing gave at many occasions valuable clues for more specific classification.

The genetic landscape of dural marginal zone lymphomas

The dura is a rare site of involvement by marginal zone lymphoma (MZL) and the biology of dural MZL is not well understood. We performed genome-wide DNA copy number and targeted mutational analysis of 14 dural MZL to determine the genetic landscape of this entity. Monoallelic and biallelic inactivation of TNFAIP3 by mutation (n=5) or loss (n=1) was observed in 6/9 (67%) dural MZL exhibiting plasmacytic differentiation, including 3 IgG4+ cases. In contrast, activating NOTCH2 mutations were detected in 4/5 (80%) dural MZL displaying variable monocytoid morphology. Inactivating TBL1XR1 mutations were identified in all NOTCH2 mutated cases. Recurrent mutations in KLHL6 (n=2) and MLL2 (n=2) were also detected. Gains at 6p25.3 (n=2) and losses at 1p36.32 (n=3) were common chromosomal imbalances, with loss of heterozygosity (LOH) of these loci observed in a subset of cases. Translocations involving the IGH or MALT1 genes were not identified. Our results indicate genetic similarities between dural MZL and other MZL subtypes. However, recurrent and mutually exclusive genetic alterations of TNFAIP3 and NOTCH2 appear to be associated with distinct disease phenotypes in dural MZL.

Del17p does not always significantly influence the survival of B-cell chronic lymphoproliferative disorders

B-cell chronic lymphoproliferative disorders (B-CLPD) comprise several entities with indolent clinical manifestations but heterogeneous survival. Cytogenetic aberrations are now the standard prognostic predictors in chronic lymphocytic leukemia (CLL) but have been less investigated in other subtypes of B-CLPD. In this study, we detected cytogenetic aberrations by fluorescence in situ hybridization (FISH) in 875 B-CLPD patients, based on a panel probes locating at 13q14, 11q22, 17p13 and CEP12. We identified del17p acted as the independent adverse cytogenetic predictor for overall survival (OS) in CLL. Del13q, del11q and del17p were adverse factors for OS in Waldenström's macroglobulinemia in the univariate analysis but lost their role in the multivariate analysis. Trisomy 12 acted as an independent poor factor for both marginal zone lymphoma (MZL) and unclassified B-CLPD (BCLPD-U) subtype. Del17p did not impact survival in MZL and BCLPD-U patients. These contrasting results indicate different roles of the same cytogenetic aberrations in the pathogenesis of each B-CLPD subtype. As del17p contributed to the poorest survival in CLL and desired extraordinary treatment strategy, the imitation of CLL strategy to other B-CLPD with del17p should be carefully advocated based on this study.

Distinct clinical characteristics draw a new prognostic model for splenic marginal zone lymphoma in HBV high prevalent region

Splenic marginal zone lymphoma (SMZL) is a rare indolent B-cell neoplasm with hepatitis virus supposed to involve in the pathogenesis. The characteristics of SMZL derived from Caucasia population and high hepatitis C virus (HCV) infection region have been widely investigated, but few was reported in the Eastern population with HBV prevalent region. We analyzed the clinical characteristics, cytogenetic aberrations and prognostic factors in 160 SMZL patients from China. 25 patients (16%) were HBsAg-positive and 54 (34%) patients with resolved HBV infection. IGH gene usage was analyzed in 39 patients. The preferential usages of IGHV genes were IGHV1-2 (26%), followed by IGHV4-34 (18%) and IGHV2-70 (10%). The patients with HBV infection presented biased IGHV-D-J rearrangements and mutational status. Using three independent factors hemoglobin level, HBsAg positivity and complex karyotype, we developed a new hierarchical prognostic model, which showed a better c-index than the previously reported IIL and HPLL scoring systems in SMZL. In conclusion, SMZL in HBV prevalent region have unique clinical and biological characteristics and new prognostic scoring model should be adopted in this population.

p53 dysregulation in B-cell malignancies: More than a single gene in the pathway to hell

TP53 deletion or mutation is frequent in B-cell malignancies and is associated with a low response rate. We describe here the p53 landscape in B-cell malignancies, from B-Acute Lymphoblastic Leukemia to Plasma Cell Leukemia, by analyzing incidence of gain or loss of function of actors both upstream and within the p53 pathway, namely MYC, RAS, ARF, MDM2, ATM and TP53. Abnormalities are not equally distributed and their incidence is highly variable among malignancies. Deletion and mutation, usually associated, of ATM or TP53 are frequent in Diffuse Large B-Cell Lymphoma and Mantle Cell Lymphoma. MYC gain, absent in post-GC malignancies, is frequent in B-Prolymphocytic-Leukemia, Multiple Myeloma and Plasma Cell Leukemias. RAS mutations are rare except in MM and PCL. Multiple Factorial Analysis notes that MYC deregulation is closely related to TP53 status. Moreover, MYC gain, TP53 deletion and RAS mutations are inversely correlated with survival. Based on this landscape, we further propose targeted therapeutic approaches for the different B-cell malignancies.