High prevalence of the MYD88 mutation in testicular lymphoma: Immunohistochemical and genetic analyses

MyD88 and Its Inhibitors in Cancer: Prospects and Challenges

The interplay between the immune system and cancer underscores the central role of immunotherapy in cancer treatment. In this context, the innate immune system plays a critical role in preventing tumor invasion. Myeloid differentiation factor 88 (MyD88) is crucial for innate immunity, and activation of MyD88 promotes the production of inflammatory cytokines and induces infiltration, polarization, and immune escape of immune cells in the tumor microenvironment. Additionally, abnormal MyD88 signaling induces tumor cell proliferation and metastasis, which are closely associated with poor prognosis. Therefore, MyD88 could serve as a novel tumor biomarker and is a promising target for cancer therapy. Current strategies targeting MyD88 including inhibition of signaling pathways and protein multimerization, have made substantial progress, especially in inflammatory diseases and chronic inflammation-induced cancers. However, the specific role of MyD88 in regulating tumor immunity and tumorigenic mechanisms remains unclear. Therefore, this review describes the involvement of MyD88 in tumor immune escape and disease therapy. In addition, classical and non-classical MyD88 inhibitors were collated to provide insights into potential cancer treatment strategies. Despite several challenges and complexities, targeting MyD88 is a promising avenue for improving cancer treatment and has the potential to revolutionize patient outcomes.

Genomic landscape and distinct molecular subtypes of primary testicular lymphoma

Primary testicular lymphoma (PTL) is a rare lymphoma predominantly occurring in the elderly male population. It is characterized by a limited response to treatment and a heightened tendency towards relapse. Histologically, approximately 90% of PTL cases are classified as diffuse large B-cell lymphomas (DLBCL). Genetic features of PTL were delineated in a limited scope within several independent studies. Some of the articles which analyzed the genetic characterization of DLBCL have incorporated PTL samples, but these have been constrained by small sample sizes. In addition, there have been an absence of independent molecular typing studies of PTL. This report summarizes the common mutational features, copy number variations (CNVs) and molecular typing of PTL patients, based on whole-exome sequencing (WES) conducted on a cohort of 25 PTL patients. Among them, HLA, CDKN2A and MYD88 had a high mutation frequency. In addition, we found two core mutational characteristics in PTL including mutation in genes linked to genomic instability (TP53 and CDKN2A) and mutation in immune-related genes (HLA, MYD88, CD79B). We performed molecular typing of 25 PTL patients into C1 subtype with predominantly TP53 mutations and C2 subtype with predominantly HLA mutations. Notably, mutations in the TP53 gene predicted a poor outcome in most types of lymphomas. However, the C1 subtype, dominated by TP53 mutations, had a better prognosis compared to the C2 subtype in PTL. C2 subtype exhibited a worse prognosis, aligning with our finding that the mechanism of immune escape in PTL was primarily the deletions of HLA rather than PD-L1/PD-L2 alterations, a contrast to other DLBCLs. Moreover, we calculated the tumor mutation burden (TMB) and identified that TMB can predict prognosis and recurrence rate in PTL. Our study underscores the significance of molecular typing in PTL based on mutational characteristics, which plays a crucial role in prognostication and guiding therapeutic strategies for patients.

MYD88L265P augments proximal B-cell receptor signaling in large B-cell lymphomas via an interaction with DOCK8

Diffuse large B-cell lymphoma (DLBCL) is a clinically and genetically heterogeneous disease with at least 5 recognized molecular subtypes. Cluster 5 (C5)/MCD tumors frequently exhibit concurrent alterations in the toll-like receptor (TLR) and B-cell receptor (BCR) pathway members, MYD88L265P and CD79B, and have a less favorable prognosis. In healthy B cells, the synergy between TLR and BCR signaling pathways integrates innate and adaptive immune responses and augments downstream NF-κB activation. In addition, physiologic TLR9 pathway engagement via MYD88, protein tyrosine kinase 2 (PYK2), and dedicator of cytokinesis 8 (DOCK8) increases proximal BCR signaling in healthy murine B cells. Although C5/MCD DLBCLs are selectively sensitive to Bruton tyrosine kinase (BTK) inhibition in in vitro studies and certain clinical trials, the role of mutated MYD88 in proximal BCR signaling remains undefined. Using engineered DLBCL cell line models, we found that concurrent MYD88L265P and CD79B alterations significantly increased the magnitude and duration of proximal BCR signaling, at the level of spleen tyrosine kinase and BTK, and augmented PYK2-dependent DOCK8 phosphorylation. MYD88L265P DLBCLs have significantly increased colocalization of DOCK8 with both MYD88 and the proximal BCR-associated Src kinase, LYN, in comparison with MYD88WT DLBCLs, implicating DOCK8 in MYD88L265P/proximal BCR cross talk. Additionally, DOCK8 depletion selectively decreased proximal BCR signaling, cellular proliferation, and viability of DLBCLs with endogenous MYD88L265P/CD79BY196F alterations and increased the efficacy of BTK blockade in these lymphomas. Therefore, MYD88L265P/DOCK8-enhanced proximal BCR signaling is a likely mechanism for the increased sensitivity of C5/MCD DLBCLs to BTK blockade.

Molecular classification and therapeutics in diffuse large B-cell lymphoma

Diffuse large B-cell lymphoma (DLBCL) encompasses a wide variety of disease states that have to date been subgrouped and characterized based on immunohistochemical methods, which provide limited prognostic value to clinicians and no alteration in treatment regimen. The addition of rituximab to CHOP therapy was the last leap forward in terms of treatment, but regimens currently follow a standardized course when disease becomes refractory with no individualization based on genotype. Research groups are tentatively proposing new strategies for categorizing DLBCL based on genetic abnormalities that are frequently found together to better predict disease course following dysregulation of specific pathways and to deliver targeted treatment. Novel algorithms in combination with next-generation sequencing techniques have identified between 4 and 7 subgroups of DLBCL, depending on the research team, with potentially significant and actionable genetic alterations. Various drugs aimed at pathways including BCR signaling, NF-κB dysfunction, and epigenetic regulation have shown promise in their respective groups and may show initial utility as second or third line therapies to patients with recurrent DLBCL. Implementation of subgroups will allow collection of necessary data to determine which groups are significant, which treatments may be indicated, and will provide better insight to clinicians and patients on specific disease course.

The Mutation of BTG2 Gene Predicts a Poor Outcome in Primary Testicular Diffuse Large B-Cell Lymphoma

Introduction

Primary testicular diffuse large B-cell lymphoma (PT-DLBCL) is a rare and aggressive form of mature B-cell lymphoma commonly found in elder males, but its genetic features are poorly understood. In this study, we had performed target-sequencing of 360 lymphoma-related genes on 76 PT-DLBCL patients with a median age of 65 (33-89). Our data provide a comprehensive understanding of the landscape of mutations in a small subset of PT-DLBCL.

Methods

A total of 76 PT-DLBCL patients were sequenced, and their clinical data and follow-up data were collected. The relationship between mutated genes, clinical data and prognosis and survival of PT-DLBCL patients was retrospectively analyzed by statistical software.

Results

We observed a median of 15 protein-altering variants per patient in our data and was identified recurrent oncogenic mutations of 360 lymphoma-related genes involved in PT-DLBCL, including PIM1 (74%), MYD88 (50%), KMT2D (38%), KMT2C (34%), BTG2 (34%), TBL1XR1 (34%) and ETV6 (24%). Compared with classic DLBCL, PT-DLBCL showed an increased mutation frequency of PIM1, MYD88, BTG2, while NOTCH1 appeared exclusive mutated with PIM1, MSH3 and ETV6. Cox risk model regression analysis showed that age ≥60 years, IPI 3-5 points, BTG2 gene mutation and extranodal organ invasion suggested poor prognosis. Finally, we constructed an OS predict model of PT-DLBCL patients using above factors with a high accuracy.

Conclusion

In conclusion, our results revealed genomic characterization of PT-DLBCL, and the mutation of BTG2 was an independent factor predicting a poor prognosis.

Primary Testicular Lymphoma with Central Nervous System Relapse Was Successfully Treated by a Chemo-Free Regimen: A Case Report and Literature Review

Primary testicular lymphoma (PTL) is a rare malignancy of testis. Although the multimodality treatment (including orchiectomy, systemic chemotherapy, scrotal radiotherapy, and preventive central nervous system (CNS)-targeted treatment) is widely used to treat PTL, recurrence, especially CNS recurrence, occurred frequently. Patients with relapsed PTL have a dismal prognosis and limited treatment options. In this report, we described the case of a 63-year-old man with early-stage PTL. The patient received the multimodality treatment, but CNS relapse occurred 3 months following the front-line therapy. We gave him a combined chemo-free regimen treatment, including rituximab, ibrutinib, and lenalidomide (RIL), based on the tumor's gene mutation profile and the patient's preference. A complete response was achieved after the first cycle of treatment. Whole-brain radiotherapy was delivered as consolidative treatment following three more cycles of RIL. Thereafter, ibrutinib and lenalidomide continued as maintenance treatment. As of the submission of this manuscript, the response has lasted for more than 16 months. Based on the case, we believe chemo-free regimen RIL might be a favorable approach for PTL patients with CNS relapse, especially those frail elderly patients, when alternative treatments are not available.

Testicular Diffuse Large B-Cell Lymphoma-Clinical, Molecular, and Immunological Features

Simple Summary

Testicular diffuse large B-cell lymphoma (T-DLBCL) is a rare and aggressive lymphoma entity that mainly affects elderly men. It has a high relapse rate with especially the relapses of the central nervous system associating with dismal outcome. T-DLBCL has a unique biology with distinct genetic characteristics and clinical presentation, and the increasing knowledge on the tumor microenvironment of T-DLBCL highlights the significance of the host immunity and immune escape in this rare lymphoma, presenting in an immune-privileged site of the testis. This review provides an update on the latest progress made in T-DLBCL research and summarizes the clinical perspectives in T-DLBCL.

Abstract

Primary testicular lymphoma is a rare lymphoma entity, yet it is the most common testicular malignancy among elderly men. The majority of the cases represent non-germinal center B-cell-like (non-GCB) diffuse large B-cell lymphoma (DLBCL) with aggressive clinical behavior and a relatively high relapse rate. Due to the rareness of the disease, no randomized clinical trials have been conducted and the currently recognized standard of care is based on retrospective analyses and few phase II trials. During recent years, the tumor microenvironment (TME) and tumor-related immunity have been the focus of many tumor biology studies, and the emergence of targeted therapies and checkpoint inhibitors has significantly modulated the field of cancer therapies. Testicular DLBCL (T-DLBCL) is presented in an immune-privileged site of the testis, and the roles of NF-κB pathway signaling, 9p24.1 aberrations, and tumor-infiltrating immune cells, especially immune checkpoint expressing lymphocytes and macrophages, seem to be unique compared to other lymphoma entities. Preliminary data on the use of immune checkpoint inhibitors in the treatment of T-DLBCL are promising and more studies are ongoing.

Clonal Evolution in Primary Diffuse Large B-Cell Lymphoma of the Central Nervous System

Primary diffuse large B-cell lymphoma (DLBCL) of the central nervous system (CNS) is an aggressive subtype of DLBCL with characteristic clinicopathologic features. Relapse outside the CNS involving extranodal locations has been found in a fraction of cases (16%). Here we describe a case of DLBCL arising in the CNS that relapsed 18 months after the initial diagnosis in the testis and bilateral adrenal glands. Both tumors showed equivalent morphology, phenotype, cytogenetic features, and clonal relationship. Somatic mutation analysis by next generation sequencing demonstrated MYD88L265P mutation in both tumors and de novo CD79B Y196S mutation exclusive to the relapse. The pattern of mutations suggest that the 2 tumors might have evolved from a common progenitor clone with MYD88L265P being the founder mutation. A meta-analysis of the literature shows a significantly high frequency of concurrent MYD88L265P and CD79B ITAM mutations in primary CNS lymphoma and testicular DLBCL, underscoring the role of B cell receptor and nuclear factor kB activation by somatic mutations in these lymphomas that colonize immune-privileged sites. In summary, here we illustrate that targeted next generation sequencing for the detection of hot spot somatic mutations in relapsed DLBCL is useful to confirm ABC phenotype and discovers relevant information that might influence therapeutic decision.

Composite monoclonal B-cell lymphocytosis and MYD88 L265P-positive lymphoplasmacytic lymphoma in a patient with IgM light chain amyloidosis: Case report

Monoclonal B-cell lymphocytosis (MBL) is an early or precursor asymptomatic proliferation of chronic lymphocytic lymphoma (CLL)-like B-cells. Lymphoplasmacytic lymphoma (LPL), often clinically associated with Waldenström macroglobulinemia, is a B-cell neoplasm characterized by frequent MYD88 L265P mutation. Here, we report a rare composite MBL and LPL in a patient with IgM light chain (AL) amyloidosis. A 74-year-old male with a known IgM monoclonal protein developed proteinuria. No lymphocytosis was detected. Renal biopsy showed deposition of AL λ amyloid in the glomeruli and vessels. Subsequent bone marrow biopsy revealed nodular atypical CLL-like small B-cell proliferation and scattered peripheral LPL. Immunohistochemistry and/or flow cytometry revealed that the atypical CLL-like population expressed CD19, CD20, CD5, weak CD23, LEF-1 and diminished surface Igκ. The LPL was positive for CD19, CD20 and surface Igλ. Using laser-capture microdissection and allele-specific polymerase chain reaction, we confirmed that MYD88 L265P was detectable in the LPL but not in the atypical CLL-like population. Thus, we demonstrated that these two populations were clonally independent, and made the diagnosis of composite MBL and LPL. An integrated clinical, pathological, immunophenotypic and genetic assessment is essential in such complicated cases, and especially 'clone-specific' MYD88 genotyping may facilitate the differential diagnoses of low-grade B-cell lymphomas.

TBL1XR1 mutation predicts poor outcome in primary testicular diffuse large B-cell lymphoma patients

Primary testicular lymphoma (PTL), often appearing as focal masses in the scrotum and epididymides, is the most frequent testicular tumor in aged men. Although MYD88 and CD79B mutations were the most common genetic alterations observed, the gene mutation landscape of PTL remains poorly defined. In this study, we identified 1326 mutations involving 311 genes or regions in 90 PTL patients through next-generation sequencing (NGS). PTL patients with the TBL1XR1 mutation, irrespective of treatment therapy, had an inferior overall survival (OS) than TBL1XR1 WT (wild type) patients (p = 0.045). Moreover, patients with this mutation, treated with a CHOP regimen (CTX 750 mg/m² iv, d1,8 ADM 50 mg/m² iv, d1 VCR 1.4 mg/m² iv, d1 PDN 100 mg/m² po d1–5), had a poorer OS (p = 0.019). In addition, such patients were prone to have a more intensive infiltration of tumors (p = 0.025, x² = 4.890). Thus, we speculated that patients with a TBL1XR1 mutation have poorer prognosis, partly due to greater invasion and infiltration of tumors. Our results suggest that the TBL1XR1 mutation can be used as an indicator to predict the prognosis of PTL and can be employed as a promising new target for treatment of PTL in the future.

Lymphoid Neoplasms With Plasmablastic Differentiation: A Comprehensive Review and Diagnostic Approaches

Plasmablastic neoplasms encompass several entities including plasmablastic lymphoma, plasmablastic plasmacytoma/multiple myeloma, primary effusion lymphoma and its extracavitary variant, anaplastic lymphoma kinase-positive large B-cell lymphoma, and Kaposi sarcoma-associated herpesvirus/human herpesvirus 8 (HHV8)-positive diffuse large B-cell lymphoma, not otherwise specified. Morphologically, the tumor cells are large with eccentrically located nuclei, prominent nucleoli, and basophilic/amphophilic cytoplasm. Immunophenotypically, the tumor cells express plasma cell-related antigens including CD38, CD138, interferon regulatory factor-4 (IRF4)/MUM1, PR domain zinc finger protein-1 (PRDM1), and/or X-box binding protein-1 (XBP1), with frequent loss of CD20. These tumors are diagnostically challenging for general pathologists due to their overlapping morphology and immunophenotype, and due to their rarity, and particularly so when clinical and radiologic information is insufficient. We also discuss HHV8-negative effusion-based lymphoma due to its overlapping features with primary effusion lymphoma. In this review, we focus on the useful diagnostic markers and pertinent molecular findings in these distinct entities and propose a practical diagnostic algorithm using anaplastic lymphoma kinase, HHV8, in situ hybridization for Epstein-Barr virus-encoded small RNA, immunoglobulin M, light chain stains, and clinicoradiologic criteria to avoid misdiagnosis. At the molecular level, MYC protein overexpression with or without MYC rearrangement and PRDM1-inactivating mutations or deletions are noted in a subset of such tumors, especially in plasmablastic lymphoma. Prognosis in these entities is dismal with conventional CHOP (cyclophosphamide, doxorubicin, vincristine, and prednisone) chemotherapy. Therefore, novel target therapies, such as anti-CD30 agents, and/or immune blockade therapy, are potential treatment options in the future.

MYD88 L265P mutation and CDKN2A loss are early mutational events in primary central nervous system diffuse large B-cell lymphomas

The genetic alterations that define primary central nervous system lymphoma (PCNSL) are incompletely elucidated, and the genomic evolution from diagnosis to relapse is poorly understood. We performed whole-exome sequencing (WES) on 36 PCNSL patients and targeted MYD88 sequencing on a validation cohort of 27 PCNSL patients. We also performed WES and phylogenetic analysis of 3 matched newly diagnosed and relapsed tumor specimens and 1 synchronous intracranial and extracranial relapse. Immunohistochemistry (IHC) for programmed death-1 ligand (PD-L1) was performed on 43 patient specimens. Combined WES and targeted sequencing identified MYD88 mutation in 67% (42 of 63) of patients, CDKN2A biallelic loss in 44% (16 of 36), and CD79b mutation in 61% (22 of 36). Copy-number analysis demonstrated frequent regions of copy loss (ie, CDKN2A), with few areas of amplification. CD79b mutations were associated with improved progression-free and overall survival. We did not identify amplification at the PD-1/PD-L1 loci. IHC for PD-L1 revealed membranous expression in 30% (13 of 43) of specimens. Phylogenetic analysis of paired primary and relapsed specimens identified MYD88 mutation and CDKN2A loss as early clonal events. PCNSL is characterized by frequent mutations within the B-cell receptor and NF-κB pathways. The lack of PD-L1 amplifications, along with membranous PD-L1 expression in 30% of our cohort, suggests that PD-1/PD-L1 inhibitors may be useful in a subset of PCNSL. WES of PCNSL provides insight into the genomic landscape and evolution of this rare lymphoma subtype and potentially informs more rational treatment decisions.

Genetic alterations and their clinical implications in DLBCL

Diffuse large B cell lymphoma (DLBCL) is a highly heterogeneous lymphoid neoplasm with variations in gene expression profiles and genetic alterations, which lead to substantial variations in clinical course and response to therapy. The advent of high-throughput genome sequencing platforms, and especially whole-exome sequencing, has helped to define the genetic landscape of DLBCL. In the past 10 years, these studies have identified many genetic alterations in DLBCL, some of which are specific to B cell lymphomas, whereas others can also be observed in other types of cancer. These aberrations result in altered activation of a wide range of signalling pathways and other cellular processes, including those involved in B cell differentiation, B cell receptor signalling, activation of the NF-κB pathway, apoptosis and epigenetic regulation. Further elaboration of the genetics of DLBCL will not only improve our understanding of disease pathogenesis but also provide further insight into disease classification, prognostication and therapeutic targets. In this Review, we describe the current understanding of the prevalence and causes of specific genetic alterations in DLBCL and their role in disease development and progression. We also summarize the available clinical data on therapies designed to target the aberrant pathways driven by these alterations.

Prevalence And Clinical Significance Of Oncogenic CD79B And MYD88 Mutations In Primary Testicular Diffuse Large B-Cell Lymphoma: A Retrospective Study In China

Purpose

In this study, we investigated the prevalence of CD79B and MYD88 mutations and their relation to clinical characteristics in a cohort of Chinese patients with primary testicular diffuse large B cell lymphoma (PT-DLBCL).

Patients and methods

We examined the mutational status of CD79B and MYD88 by Sanger sequencing, and the gene amplification and protein expression of MYD88 in tissue samples from 30 cases of PT-DLBCL by quantitative polymerase chain reaction and immunohistochemistry, respectively. Western blotting was used to analyze phosphorylated STAT3 (p-STAT3) and phosphorylated p65 (p-p65) protein expression in cell lines harboring retroviral constructs for WT MYD88 or MYD88 mutant.

Results

Immunophenotypically, MYD88 protein staining was positive in 26/30 (86.67%) cases, and 23/30 (76.7%) cases tested positive for p65 in the nucleus. Genetically, CD79B mutation was found in 13/30 (43.3%) cases, whereas the MYD88^L265P mutation was found in 18/30 (60.0%) cases. Interestingly, CD79B and MYD88 mutations were more prevalent in the non-germinal center B cell (GCB) subtype (83.3% and 76.9%, respectively) and were relatively rare in the GCB subtype (16.7% and 23.1%, respectively). Furthermore, although MYD88 was significantly amplified in PT-DLBCL, the amplification status showed no correlation with its mutational status and protein expression. Clinicopathological comparison between the mutant and wild-type group showed that both CD79B mutation and MYD88^L265P were not significantly correlated with age, anatomical site, Ann Arbor stage, non-GCB/GCB subtype, p65 protein expression, BCL-2 protein expression, or BCL-2/c-MYC double expression (P>0.05). Survival analyses showed that high IPI and advanced stage (stage III–IV) associated with worse outcome (P<0.05). The expression of p-STAT3 and p-p65 protein was upregulated in the mutant group, indicating that MYD88 mutant activated NF-κB and JAK–STAT3 signaling.

Conclusion

Our results suggest that MYD88 and CD79B mutations are important drivers of immune-privileged site-associated DLBCL and highlight potential therapeutic targets for personalized treatment.

Clinical Relevance of the High Prevalence of MYD88 L265P Mutated Vitreoretinal Lymphoma Identified by Droplet Digital Polymerase Chain Reaction

Purpose: To investigate the frequency and clinical relevance of missense mutation at position 265 changing leucine to proline in the myeloid differentiation factor 88 gene (MYD88 L265P) in the vitreous of Chinese patients with vitreoretinal lymphoma (VRL) using droplet digital polymerase chain reaction (ddPCR).Methods: Vitreous fluid (VF) from 29 eyes of 20 VRL patients at the North Huashan Hospital were included. MYD88 L265P analysis of VF was performed using ddPCR. Associations between clinicopathologic characteristics and MYD88 mutation were analyzed using t-test or Fisher's exact test.Results: MYD88 L265P mutations were detected in 22 of 29 samples from 14 patients with diffuse large B-cell lymphomas and one patient with lymphoplasmacytoid lymphoma. However, no significant associations were found between MYD88 L265P mutation status and age, sex, lymphoma subtype or location of the primary lesion.Conclusion: The high prevalence of MYD88 L265P identified by ddPCR suggests that this method of evaluating the frequency of MYD88 L265P is a promising tool for accurate diagnosis of VRL.

Follicular Lymphoma Presenting With Monoclonal IgM And MYD88 Mutation: A Case Report And Review Of The Literature

MYD88 mutation has been reported in various lymphomas, specifically in lymphoplasmacytic lymphoma. Yet, the mutation has not been reported in primary follicular lymphoma. Here, we present a 62-year-old male with follicular lymphoma who had an MYD88 L265P somatic mutation and monoclonal IgM gammopathy. He received four cycles of R-CHOP immunochemotherapy. Interim PET/CT evaluation indicated a state of stable disease (SD). Neither did serum IgM remarkably drop. He was then given a bortezomib-contained regimen which significantly reduced the level of serum IgM. To the best of our knowledge, this is the first report of follicular lymphoma with monoclonal IgM and MYD88 L265P mutation. The present case indicated bortezomib may benefit these patients.

Clinicopathologic correlates of MYD88 L265P mutation and programmed cell death (PD-1) pathway in primary central nervous system lymphoma

Primary central nervous system lymphoma (PCNSL) patients have a poorer prognosis than systemic lymphoma. Gain-of-function MYD88 c.794T > C (p. L265P) mutation and programed cell death-1 (PD-1) pathway alterations are potential targetable pathways. Our study objective was to determine the clinicopathologic correlates of MYD88 mutation and PD-1 alterations in PCNSL and the impact of Epstein-Barr virus (EBV) infection. We studied 53 cases including 13 EBV-associated (EBV^pos) PCNSL, 49% harbored MYD88 mutation, none seen in EBV^pos PCNSL. MYD88 protein expression did not correlate with MYD88 mutation. T-cell and macrophage infiltration was common. All PD-L1-positive tumors were EBV^pos. Two PD-L1 positive tumors showed 9p24.1/PD-L1 locus alterations by Fluorescence In Situ Hybridization. T cells and macrophages expressed PD-1 and/or PD-L1 in 98% and 83% cases, respectively. MYD88 mutation or protein expression and PD-1 or PD-L1 expression did not predict outcome. We hypothesize that EBV^pos PCNSL has a distinct activation mechanism, independent of genetic alterations.

Clinical Impact of the 2016 Update to the WHO Lymphoma Classification

OPINION STATEMENT

The 2016 revision of the WHO classification of lymphoid neoplasms includes new entities along with a clearer definition of provisional and definitive subtypes based on better understanding of the molecular drivers of lymphomas. These changes impact current treatment paradigms and provide a framework for future clinical trials. Additionally, this update recognizes several premalignant or predominantly indolent entities and underscores the importance of avoiding unnecessarily aggressive treatment in the latter subsets.

Extranodal Diffuse Large B Cell Lymphoma: Molecular Features, Prognosis, and Risk of Central Nervous System Recurrence

OPINION STATEMENT

Diffuse large B cell lymphoma (DLBCL) arises from extranodal organs in about 30% of cases. Its prognosis and risk of recurrence in the central nervous system (CNS) vary according to the primary site of origin. Recent studies begin to clarify these differences using molecular classification. Testicular, breast, and uterine DLBCL (as well as possibly primary cutaneous DLBCL, leg-type) share a high prevalence of the non-germinal center B cell (non-GCB) phenotype and the MYD88/CD79B-mutated (MCD) genotype. These biologic features, which resemble primary CNS lymphoma, may underlie their stage-independent propensity for CNS involvement. Management of these lymphomas should involve CNS prophylaxis, preferably using systemic high-dose methotrexate to prevent intraparenchymal recurrence. Involvement of the kidneys, adrenal glands, ovary, bone marrow, lung, or pleura usually indicates disseminated disease, conferring worse prognosis. Involvement of these sites is often associated with high CNS-International Prognostic Index (IPI), concurrent MYC and BCL2 or BCL6 rearrangements, or intravascular lymphoma-risk factors warranting CNS prophylaxis. In contrast, craniofacial, thyroid, localized bone, or gastric lymphomas have a variable prevalence of the non-GCB phenotype and lack MYD88 mutations. Their outcomes with standard immunochemotherapy are excellent, and the risk of CNS recurrence is low. We recommend individualized consideration of CNS prophylaxis based on the CNS-IPI score and anatomical proximity in cases of epidural, orbital, or skull involvement. Rituximab-containing immunochemotherapy is a standard approach for all extranodal DLBCLs. Surgery is no longer required for any primary site, but routine consolidative radiation therapy is recommended for testicular lymphoma. Radiation therapy also appears to be associated with better progression-free survival in primary bone DLBCL. Future studies should better distinguish primary from secondary sites of extranodal involvement, and investigate the association of newly identified genotypes with the risk of CNS or systemic recurrence.

Prognostic relevance of protein expression, clinical factors, and MYD88 mutation in primary bone lymphoma

Primary bone lymphomas (PBLs) are composed of malignant lymphoid cells presenting in osseous sites, without supra-regional lymph node or extranodal involvement. We systematically characterized the immunophenotype and the myeloid differentiation factor 88 (MYD88)-L265P gene mutation status in PBL. Clinical data from 19 patients with PBL treated at Nanjing Drum Tower Hospital between 2009 and 2015 were analyzed retrospectively. Protein expression patterns were identified immunohistochemically, and MYD88 mutation was assessed using polymerase chain reaction and direct DNA sequencing. Fifteen patients presented with diffuse large B-cell lymphoma. Clinical factors favoring a good prognosis were an age < 60 years and rituximab treatment. B-cell lymphoma 2 expression was detected in 5/15 diffuse large B-cell lymphoma patients, and was associated with a poor prognosis in a univariate model. Janus kinase/signal transducer and activator of transcription 3 (JAK/STAT3) signaling factors were upregulated in PBLs. All eighteen evaluable PBL samples harbored wild-type MYD88. These data thus suggest that age and rituximab treatment are independent prognostic factors determining overall survival, and that activation of JAK/STAT3 signaling may promote the pathogenesis of PBL. Moreover, the absence of MYD88-L265P mutation in PBL indicate there are distinct pathogenetic backgrounds among extranodal lymphomas.

Clinicopathologic significance of MYD88 L265P mutation in diffuse large B-cell lymphoma: a meta-analysis

The precise clinicopathologic significance of myeloid differentiation primary response gene (MYD88) L265P mutation in diffuse large B-cell lymphomas (DLBCLs) remains elusive. To investigate the frequency and clinicopathologic significance of the MYD88 L265P mutation in DLBCLs, we conducted a meta-analysis of 40 published studies on 2736 DLBCL patients. We collected relevant published research findings identified using the PubMed and Embase databases. The effect sizes of outcome parameters were calculated using a random-effects model. In this meta-analysis, the MYD88 L265P mutation in DLBCL showed a significant difference according to tumor sites. The overall incidence of the MYD88 L265P mutation in DLBCLs, excluding the central nervous system and testicular DLBCLs, was 16.5%. Notably, the MYD88 L265P mutation rates of CNS and testicular DLBCL patients were 60% and 77%, respectively. Interestingly, the MYD88 L265P mutation was more frequently detected in activated B-cell-like (ABC) or non-germinal center B-cell-like (GCB) than GCB subtype (OR = 3.414, p < 0.001). The MYD88 L265P mutation was significantly associated with old age and poor overall survival, but not with sex and clinical stage. This pooled analysis demonstrates that the MYD88 L265P mutation is significantly associated with the tumor sites and molecular subtypes in DLBCL patients.

PREVALENCE OF MYD88 L265P MUTATION IN HISTOLOGICALLY PROVEN, DIFFUSE LARGE B-CELL VITREORETINAL LYMPHOMA

PURPOSE

Myeloid differentiation primary response gene 88 (MYD88) is a universal adaptor protein in the innate immune system. When associated with a proline for leucine substitution mutation at position 265 (L265P), the protein becomes constitutively activated, amplifying the intracellular pro-inflammatory signal. Recently, we reported two cases of vitreoretinal lymphoma (VRL) that were positive for the mutation. The purpose of this study was to determine prevalence of the MYD88 L265P mutation in a larger series of VRL.

METHODS

Retrospective chart review of 25 patients with histologically confirmed VRL evaluated at Mayo Clinic, Rochester, between January 2000 and March 2015. Paraffin-embedded blocks from the vitreous were submitted for polymerase chain reaction testing of the L265P mutation.

RESULTS

The mutation was positive in 82.4% of all VRL cases and 86.7% of primary VRL cases. The minimum necessary DNA concentration needed for the polymerase chain reaction assay was 4.93 ng/mL.

CONCLUSION

MYD88 gene analysis is a helpful ancillary tool for diagnosing VRL. It often requires fewer cells than flow cytometry or cytology and may be especially useful in early cases where a sufficient number of cells may not be available.

Recent Advances in Aggressive Large B-cell Lymphomas: A Comprehensive Review

Diffuse large B-cell lymphoma (DLBCL) is an aggressive disease with considerable heterogeneity reflected in the 2008 World Health Organization classification. In recent years, genome-wide assessment of genetic and epigenetic alterations has shed light upon distinct molecular subsets linked to dysregulation of specific genes or pathways. Besides fostering our knowledge regarding the molecular complexity of DLBCL types, these studies have unraveled previously unappreciated genetic lesions, which may be exploited for prognostic and therapeutic purposes. Following the last World Health Organization classification, we have witnessed the emergence of new variants of specific DLBCL entities, such as CD30 DLBCL, human immunodeficiency virus-related and age-related variants of plasmablastic lymphoma, and EBV DLBCL arising in young patients. In this review, we will present an update on the clinical, pathologic, and molecular features of DLBCL incorporating recently gained information with respect to their pathobiology and prognosis. We will emphasize the distinctive features of newly described or emerging variants and highlight advances in our understanding of entities presenting a diagnostic challenge, such as T-cell/histiocyte-rich large B-cell lmphoma and unclassifiable large B-cell lymphomas. Furthermore, we will discuss recent advances in the genomic characterization of DLBCL, as they may relate to prognostication and tailored therapeutic intervention. The information presented in this review derives from English language publications appearing in PubMed throughout December 2015. For a complete outline of this paper, please visit: http://links.lww.com/PAP/A12.

Targetable genetic features of primary testicular and primary central nervous system lymphomas

Primary central nervous system lymphomas (PCNSLs) and primary testicular lymphomas (PTLs) are extranodal large B-cell lymphomas (LBCLs) with inferior responses to current empiric treatment regimens. To identify targetable genetic features of PCNSL and PTL, we characterized their recurrent somatic mutations, chromosomal rearrangements, copy number alterations (CNAs), and associated driver genes, and compared these comprehensive genetic signatures to those of diffuse LBCL and primary mediastinal large B-cell lymphoma (PMBL). These studies identify unique combinations of genetic alterations in discrete LBCL subtypes and subtype-selective bases for targeted therapy. PCNSLs and PTLs frequently exhibit genomic instability, and near-uniform, often biallelic, CDKN2A loss with rare TP53 mutations. PCNSLs and PTLs also use multiple genetic mechanisms to target key genes and pathways and exhibit near-uniform oncogenic Toll-like receptor signaling as a result of MYD88 mutation and/or NFKBIZ amplification, frequent concurrent B-cell receptor pathway activation, and deregulation of BCL6. Of great interest, PCNSLs and PTLs also have frequent 9p24.1/PD-L1/PD-L2 CNAs and additional translocations of these loci, structural bases of immune evasion that are shared with PMBL.