Cryptic insertions of the immunoglobulin light chain enhancer region near CCND1 in t(11;14)-negative mantle cell lymphoma

Cytogenetics in the management of mature B-cell non-Hodgkin lymphomas: Guidelines from the Groupe Francophone de Cytogénétique Hematologique (GFCH)

Non-Hodgkin lymphomas (NHL) consist of a wide range of clinically, phenotypically and genetically distinct neoplasms. The accurate diagnosis of mature B-cell non-Hodgkin lymphoma relies on a multidisciplinary approach that integrates morphological, phenotypical and genetic characteristics together with clinical features. Cytogenetic analyses remain an essential part of the diagnostic workup for mature B-cell lymphomas. Karyotyping is particularly useful to identify hallmark translocations, typical cytogenetic signatures as well as complex karyotypes, all bringing valuable diagnostic and/or prognostic information. Besides the well-known recurrent chromosomal abnormalities such as, for example, t(14;18)(q32;q21)/IGH::BCL2 in follicular lymphoma, recent evidences support a prognostic significance of complex karyotype in mantle cell lymphoma and Waldenström macroglobulinemia. Fluorescence In Situ Hybridization is also a key analysis playing a central role in disease identification, especially in genetically-defined entities, but also in predicting transformation risk or prognostication. This can be exemplified by the pivotal role of MYC, BCL2 and/or BCL6 rearrangements in the diagnostic of aggressive or large B-cell lymphomas. This work relies on the World Health Organization and the International Consensus Classification of hematolymphoid tumors together with the recent cytogenetic advances. Here, we review the various chromosomal abnormalities that delineate well-established mature B-cell non-Hodgkin lymphoma entities as well as newly recognized genetic subtypes and provide cytogenetic guidelines for the diagnostic management of mature B-cell lymphomas.

[Classification of indolent B-cell lymphomas : Novelties and open questions]

The 5th edition of the WHO classification (WHO-HAEM5) and the International Consensus Classification (ICC) have considerable overlap but also some distinct differences in categorizing indolent B‑cell lymphomas. Most differences with the expected impact on the daily diagnostic routine relate to follicular lymphoma (FL). Grading of FL remains mandatory only in the ICC; a diffuse growth pattern in an FL with > 15 blasts per high-power field (FL grade 3A) is not automatically classified as DLBCL according to WHO-HAEM5, and an FL subtype with unusual morphology (blastoid or large centrocyte) and biology is recognized as an entity only in the WHO-HAEM5. With the exception of B‑prolymphocytic leukemia, which is no longer acknowledged in WHO-HAEM5, there are only minor differences between both classifications and include updated names of entities, improved diagnostic criteria, and upgrades from provisional to definite entities.

Case report: Identification of atypical mantle cell lymphoma with CCND3 rearrangement by next-generation sequencing

The t(11;14) (q13;q32) translocation resulting in overexpression of cyclin D1 is the major oncogenic mechanism in mantle cell lymphoma (MCL). Most MCLs can be diagnosed based on morphological features, cyclin D1 expression, and IGH/CCND1 rearrangement. However, in some atypical cases where conventional FISH studies fail to detect IGH/CCND1 rearrangement or immunohistochemistry for cyclin D1 is negative, the diagnosis of the disease can be difficult. Hence, next-generation sequencing (NGS) may allow the identification of molecular alterations and assist in the diagnosis of atypical MCL. In this study, we reported a case of a patient diagnosed as asymptomatic MCL who presented with lymphadenopathy during the initial assessment. A lymph node biopsy was performed and the results revealed a high Ki67 index. However, initial diagnosis of aggressive MCL was difficult since the IGH/CCND1 rearrangement result was negative. Ultimately, by the aid of NGS we identified a rare CCND3 rearrangement in the patient, which lead to overexpression of cyclin D3, thereby facilitating the diagnosis of MCL.

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.

Mantle cell lymphoma negative for t(11,14) involving the kidneys: a case report

Background

Mantle cell lymphoma is the rarest subtype of non-Hodgkin’s lymphoma. It can exhibit diverse extranodal manifestations. However, renal involvement is uncommon, and if it occurs, it usually only gets detected postmortem. There are several mechanisms by which mantle cell lymphoma can damage the kidneys. Renal failure is a potential complication, and prompt evaluation and diagnosis are critical steps to prevent long-term complications.

Case presentation

We present the case of a 75-year-old non-Hispanic White male with past medical history significant for hypertension and dyslipidemia, presenting with fever, weight loss, and night sweats. Work-up showed markedly elevated white blood cells, multiple enlarged lymph nodes, and a kidney mass. The patient was diagnosed with mantle cell lymphoma with kidney involvement confirmed with a kidney biopsy. His disease was positive for cyclin D1 overexpression despite t(11; 14) absence. The patient received six cycles of alternating vincristine, rituximab, cyclophosphamide, doxorubicin, and prednisone then dexamethasone, high-dose cytarabine, and oxaliplatin, after which he was maintained on ibrutinib and rituximab, with resolution of symptoms and disease regression.

Conclusion

We present a case of a rare presentation of Mantle cell lymphoma while describing the clinical presentation and diagnostic and treatment approaches. This case report can assist physicians in the clinical work-up and treatment of patients with similar diagnosis or presentation.

Current Knowledge in Genetics, Molecular Diagnostic Tools, and Treatments for Mantle Cell Lymphomas

Mantle Cell lymphoma (MCL) is a mature B-cell lymphoma with a well-known hallmark genetic alteration in most cases, t (11,14)(q13q32)/CCND1-IGH. However, our understanding of the genetic and epigenetic alterations in MCL has evolved over the years, and it is now known that translocations involving CCND2, or cryptic insertion of enhancer elements of IGK or IGL gene, can also lead to MCL. On a molecular level, MCL can be broadly classified into two subtypes, conventional MCL (cMCL) and non-nodal MCL (nnMCL), each with different postulated tumor cell origin, clinical presentation and behavior, mutational pattern as well as genomic complexity. This article reviews both the common and rare alterations in MCL on a gene mutational, chromosomal arm, and epigenetic level, in the context of their contribution to the lymphomagenesis and disease evolution in MCL. This article also summarizes the important prognostic factors, molecular diagnostic tools, and treatment options based on the most recent MCL literature.

Enhancing B-Cell Malignancies-On Repurposing Enhancer Activity towards Cancer

B-cell lymphomas and leukemias derive from B cells at various stages of maturation and are the 6th most common cancer-related cause of death. While the role of several oncogenes and tumor suppressors in the pathogenesis of B-cell neoplasms was established, recent research indicated the involvement of non-coding, regulatory sequences. Enhancers are DNA elements controlling gene expression in a cell type- and developmental stage-specific manner. They ensure proper differentiation and maturation of B cells, resulting in production of high affinity antibodies. However, the activity of enhancers can be redirected, setting B cells on the path towards cancer. In this review we discuss different mechanisms through which enhancers are exploited in malignant B cells, from the well-studied translocations juxtaposing oncogenes to immunoglobulin loci, through enhancer dysregulation by sequence variants and mutations, to enhancer hijacking by viruses. We also highlight the potential of therapeutic targeting of enhancers as a direction for future investigation.

Molecular Pathogenesis of Mantle Cell Lymphoma

Mantle cell lymphoma (MCL) is a mature B-cell neoplasm with heterogeneous clinical behavior molecularly characterized by the constitutive overexpression of cyclin D1 and deregulation of different signaling pathways. SOX11 expression determines an aggressive phenotype associated with accumulation of many chromosomal alterations and somatic gene mutations. A subset of patients with the SOX11-negative leukemic non-nodal MCL subtype follows an initial indolent clinical evolution and may not require treatment at diagnosis, although eventually may progress to an aggressive disease. We discuss the genetic and molecular alterations with impact on the cancer hallmarks that characterize the lymphomagenesis of the 2 MCL subtypes.