Clinical, pathological and genetic features of primary mediastinal large B-cell lymphomas and mediastinal gray zone lymphomas in children

The Complex Relationship between Mechanisms Underlying Inflammatory Bowel Disease, Its Treatment, and the Risk of Lymphomas: A Comprehensive Review

Patients with inflammatory bowel disease may be at higher risk of developing lymphomas and other cancers of the gastrointestinal tract. In addition, there may be a link between the use of thiopurines or anti-tumor necrosis factor drugs (anti-TNF) and these pathologies. The treatment of patients with Crohn's disease who have previously been diagnosed with lymphoma is a challenge for gastroenterologists. In this report, we examine important clinical issues related to the treatment of patients with inflammatory bowel disease with active lymphoma, as well as of patients with hematological cancer history. In this discussion, we take into account most of the available treatments for inflammatory bowel disease, as well as the impact of chronic inflammation and viral infections. In addition, we try to find common ground for the development of lymphoproliferative disorders and autoimmune diseases. Patients with inflammatory bowel disease may be at higher risk of developing lymphomas and other cancers of the gastrointestinal tract. Chronic inflammatory processes and viral infections play an important role in carcinogenesis. In addition, there may be a link between the use of thiopurines or anti-TNF drugs and these pathologies. A significant risk of the development of lymphoma in people undergoing each therapy should be considered, and it should be estimated how much greater this risk will be in patients with a history of lymphoproliferative disorders. The following review is an attempt to answer which therapy would be the most appropriate for patients with Crohn's disease and a history of lymphoma treatment. A lack of clear guidelines creates great challenges for doctors.

Prognostic factors and clinical survival outcome in patients with primary mediastinal diffuse large B-cell lymphoma in rituximab era: A population-based study

The goal of this study was to investigate the clinical characteristics, prognostic variables, and survival of patients with primary mediastinal diffuse large B cell lymphoma (PMBCL) in the rituximab era. The Surveillance, Epidemiology, and End Results (SEER) database was used to identify PMBCL patients diagnosed between 2000 and 2019. The Kaplan-Meier (K-M) technique and log-rank test were used to assess overall survival (OS) and disease-specific survival (DSS). The independent prognostic variables for OS and DSS were identified using univariate and multivariate Cox regression analysis. Nomograms were created to predict survival prospects according to identified prognostic indicators. Totally, 841 patients were enrolled with PMBCL. One-year, 5-year, and 10-year OS rates were 93.99%, 85.04%, and 81.76%, and the corresponding DSS rates were 95.27%, 87.37%, and 85.98%. The results of multivariate Cox regression analysis demonstrated that age, years of diagnosis, Ann arbor staging, and chemotherapy were independent prognostic factors for survival. Nomograms designed exclusively for PMBCL were created to forecast the likelihood of 1-year, 5-year, and 10-year OS and DSS, respectively. The Harrell concordance index (C-index) for the nomograms predictions of OS and DSS were 0.704 and 0.733, respectively, which showed the established model harboring powerful and accurate performance. The present study revealed that incidence of PMBCL has been consistently rising over the last 20 years. Simultaneously, survival rates have improved tremendously. Rituximab based immunochemotherapy has emerged as an effective treatment option, leading to enhanced OS and DSS outcomes. Furthermore, the nomograms specifically developed for PMBCL have demonstrated robustness and accuracy in forecasting OS and DSS rates at 1, 5, and 10 years. These predictive tools can be valuable for clinicians in accurately estimating prognosis and establishing personalized treatment plans and follow-up protocols.

Updates in the Management of Primary Mediastinal B Cell Lymphoma

Primary mediastinal B cell lymphoma (PMBCL) is considered a distinct pathology according to the WHO classification of lymphoid malignancies. Patients have a better prognosis after the addition of Rituximab to anthracycline-based chemotherapy. The role of consolidative radiotherapy is controversial after the approval of dose-adjusted R-EPOCH and the selection of patients to undergo radiotherapy is based on end-of-therapy PET CT. In the relapsed/refractory setting, new approved drugs and other under investigation have improved patient outcomes. This review summarizes the different treatment modalities in (PMBCL) in the frontline and the relapsed/refractory settings.

Aggressive non-Hodgkin lymphoma in the pediatric and young adult population; diagnostic and molecular pearls of wisdom

Mature non-Hodgkin lymphomas (NHLs) of the pediatric and young adults(PYA), including Burkitt lymphoma (BL), diffuse large B cell lymphoma (DLBCL), high-grade B cell lymphoma (HGBCL), primary mediastinal large B cell lymphoma (PMBL) and anaplastic large cell lymphoma (ALCL), generally have excellent prognosis compared to the adult population. BL, DLBCL and HGBCL are usually of germinal center (GCB) origin in the PYA population. PMBL neither belongs to the GCB nor the activated B cell subtype and is associated with a poorer outcome than BL or DLBCL of comparable stage. Anaplastic large cell lymphoma is the most frequent peripheral T cell lymphoma occurring in the PYA and accounts for 10-15% of childhood NHL. Most pediatric ALCL, unlike in the adult, demonstrate expression of anaplastic lymphoma kinase (ALK). In recent years, the understanding of the biology and molecular features of these aggressive lymphomas has increased tremendously. This has led to reclassification of newer PYA entities including Burkitt-like lymphoma with 11q aberration. In this review, we will discuss the current progress discovered in frequently encountered aggressive NHLs in the PYA, highlighting the clinical, pathologic and molecular features that aid in the diagnosis of these aggressive lymphomas. We will be updating the new concepts and terminologies used in the new classification systems.

Evolution in the definition and diagnosis of the Hodgkin lymphomas and related entities

Hodgkin lymphoma was the first of the lymphomas to be recognized as a specific disease entity. However, recent studies have highlighted the heterogeneity of the diseases associated with this eponym warranting clarification and refinement of diagnostic terminology. While classic Hodgkin lymphoma (CHL) remains an essentially unchanged diagnostic entity in the 2022 International Consensus Classification of Mature Lymphoid Neoplasms (2022 ICC), nodular lymphocyte predominant Hodgkin lymphoma (NLPHL) is now renamed nodular lymphocyte predominant B cell lymphoma (NLPBL) in recognition of the distinct pathologic, biologic, and clinical differences. Fan patterns A, B, and C (sharing the presence of evident follicular structures, and retention of a B cell rich background) will be combined in "typical" or grade 1, while the other "variant" patterns, D, E, and F, are considered grade 2. T-cell/histiocyte-rich large B cell lymphoma (THRBCL) is considered part of the "variant" NLPHL continuum.The entity previously known as "B cell lymphoma, unclassifiable (BCLU), with features intermediate between diffuse large B cell lymphoma (DLBCL) and CHL" has been renamed "mediastinal gray zone lymphoma" (MGZL) in recognition of the importance of the thymic niche in the biology of this tumor. The diagnostic criteria for MGZL have been refined and require both a high tumor cell density and a strongly preserved B cell program.This article will describe updates on CHL, NLPBL, and MGZL in the recently published 2022 ICC and provide some useful differential diagnostic clues in cases with atypical morphology or immunophenotype.

A comparison of the International Consensus and 5th World Health Organization classifications of mature B-cell lymphomas

Several editions of the World Health Organization (WHO) classifications of lympho-hemopoietic neoplasms in 2001, 2008 and 2017 served as the international standard for diagnosis. Since the 4th WHO edition, here referred as WHO-HAEM4, significant clinico-pathological, immunophenotypic and molecular advances have been made in the field of lymphomas, contributing to refining diagnostic criteria of several diseases, to upgrade entities previously defined as provisional and to identify new entities. This process has resulted in two recent classifying proposals of lymphoid neoplasms, the International Consensus Classification (ICC) and the 5th edition of the WHO classification (WHO-HAEM5). In this paper, we review and compare the two classifications in terms of diagnostic criteria and entity definition, with focus on mature B-cell neoplasms. The main aim is to provide a tool to facilitate the work of pathologists, hematologists and researchers involved in the diagnosis and treatment of lymphomas.

Plasticity in Classical Hodgkin Composite Lymphomas: A Systematic Review

The co-occurrence of several lymphomas in a patient defines composite/synchronous lymphoma. A common cellular origin has been reported for both contingents of such entities. In the present review, we aimed to gather the available data on composite lymphomas associating a classical Hodgkin lymphoma (cHL) with another lymphoma, to better understand the plasticity of mature B and T-cells. This review highlights that >70% of patients with a composite lymphoma are ≥55 years old, with a male predominance. The most reported associations are cHL with follicular lymphoma or diffuse large B-cell lymphoma, with over 130 cases reported. The cHL contingent is often of mixed cellularity type, with a more frequent focal/weak CD20 expression (30% to 55.6%) compared to de novo cHL, suggesting a particular pathophysiology. Moreover, Hodgkin cells may express specific markers of the associated lymphoma (e.g., BCL2/BCL6 for follicular lymphoma and Cyclin D1 for mantle cell lymphoma), sometimes combined with common BCL2/BCL6 or CCND1 rearrangements, respectively. In addition, both contingents may share similar IgH/IgK rearrangements and identical pathogenic variants, reinforcing the hypothesis of a common clonal origin. Finally, cHL appears to be endowed with a greater plasticity than previously thought, supporting a common clonal origin and a transdifferentiation process during lymphomagenesis of composite lymphomas.

Pediatric Aggressive Mature B-Cell Lymphomas, Version 3.2022, NCCN Clinical Practice Guidelines in Oncology

NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines) for Pediatric Aggressive Mature B-Cell Lymphomas include recommendations for the diagnosis and management of pediatric patients with primary mediastinal large B-cell lymphoma (PMBL) and sporadic variants of Burkitt lymphoma and diffuse large B-cell lymphoma. PMBL is now considered as a distinct entity arising from mature thymic B-cells accounting for 2% of mature B-cell lymphomas in children and adolescents. This discussion section includes the recommendations outlined in the NCCN Guidelines for the diagnosis and management of pediatric patients with PMBL.

Management of Aggressive Non-Hodgkin Lymphomas in the Pediatric, Adolescent, and Young Adult Population: An Adult vs. Pediatric Perspective

Simple Summary

This review details the diagnosis and treatment of primary non-Hodgkin lymphoma (NHL) in the pediatric and adolescent population. We also describe treatment modalities such as hematopoietic stem cell transplantation for relapsed or refractory NHL in patients that fail or do not respond to the initial therapy. We then detail the current advancements in treatment for patients that fail initial therapy such as CAR T-cell therapy, the use of immunotherapy that target surface makers on malignant cells and highlight areas where further research is needed. The purpose of our review is to inform the pediatric oncology community in regard to the various types of NHLs and emphasize areas where the science is evolving in the treatment of primary, relapsed or refractory disease.

Abstract

Non-Hodgkin lymphoma (NHL) is a broad entity which comprises a number of different types of lymphomatous malignancies. In the pediatric and adolescent population, the type and prognosis of NHL varies by age and gender. In comparison to adults, pediatric and adolescent patients generally have better outcomes following treatment for primary NHL. However, relapsed/refractory (R/R) disease is associated with poorer outcomes in many types of NHL such as diffuse large B cell lymphoma and Burkitt lymphoma. Newer therapies have been approved in the use of primary NHL in the pediatric and adolescent population such as Rituximab and other therapies such as chimeric antigen receptor T-cell (CAR T-cell) therapy are under investigation for the treatment of R/R NHL. In this review, we feature the characteristics, diagnosis, and treatments of the most common NHLs in the pediatric and adolescent population and also highlight the differences that exist between pediatric and adult disease. We then detail the areas of treatment advances such as immunotherapy with CAR T-cells, brentuximab vedotin, and blinatumomab as well as cell cycle inhibitors and describe areas where further research is needed. The aim of this review is to juxtapose established research regarding pediatric and adolescent NHL with recent advancements as well as highlight treatment gaps where more investigation is needed.

The Grey Zones of Classic Hodgkin Lymphoma

Simple Summary

Classic Hodgkin lymphoma (CHL) is a well-defined lymphoid neoplasm with a minority of characteristic neoplastic cells of B cell origin, namely Hodgkin and Reed–Sternberg cells immersed in a rich reactive inflammatory infiltrate in the background. Although CHL has always been set apart from non-Hodgkin lymphomas, cases with morphological and phenotypic features intermediate between CHL and other lymphomas have been described. Whereas some of these lymphomas only represent morphological mimics, others exhibit mutational and gene expression profiles which overlap with CHL, indicating that these cases, frequently termed grey zone lymphomas, reside on the biological boundary between CHL and large B-cell lymphomas. In the present review, we aim to describe the current knowledge of these rare lymphomas, address diagnostic issues and summarize today’s concepts on the classification of grey zone lymphomas and related tumors.

Abstract

Classic Hodgkin lymphoma (CHL) is a well-defined neoplasm characterized by the presence of a minority of pathognomonic Hodgkin and Reed–Sternberg (HRS) cells in a reactive inflammatory background. Although genotypically of B cell origin, HRS cells exhibit a downregulated B cell program and therefore are set apart from other B cell lymphomas in the current WHO classification. However, cases with morphological and phenotypic features overlapping with CHL have been recognized, and the category of B cell lymphoma—unclassifiable—with features intermediate between diffuse large B cell lymphoma (DLBCL) and CHL, also termed grey zone lymphoma, was first introduced into the WHO classification in 2008 as provisional entity. These cases, as well as others raising a differential diagnosis of CHL can present diagnostic problems, as well as therapeutic challenges. Whereas some of these lymphomas only represent biologically unrelated morphological mimics, others, especially mediastinal grey zone lymphoma, exhibit genetic and gene expression profiles which overlap with CHL, indicating a true biological relationship. In this review, we address areas of diagnostic difficulties between CHL and other lymphoma subtypes, discuss the biological basis of true grey zone lymphoma based on recent molecular studies and delineate current concepts for the classification of these rare tumors.

Dose-Adjusted Etoposide, Doxorubicin, and Cyclophosphamide With Vincristine and Prednisone Plus Rituximab Therapy in Children and Adolescents With Primary Mediastinal B-Cell Lymphoma: A Multicenter Phase II Trial

PURPOSE

A dose-adjusted etoposide, doxorubicin, and cyclophosphamide with vincristine and prednisone plus rituximab (DA-EPOCH-R) regimen has been shown to deliver excellent survival for adults with primary mediastinal large B-cell lymphoma (PMLBL) without the use of radiotherapy. No international prospective evaluation of this regimen has previously been reported in children and adolescents.

PATIENTS AND METHODS

We conducted an international single-arm phase II trial involving patients younger than age 18 years with PMLBL who were to receive six courses of DA-EPOCH-R. The primary end point was event-free survival (EFS). Overall survival and toxicity were also assessed. This trial was registered (ClinicalTrials.gov identifier: NCT01516567).

RESULTS

Analyses were based on 46 patients. The median age was 15.4 years (interquartile range: 14-16 years). The median follow-up was 59.0 months (interquartile range: 52.6-69.2 months). Fourteen events were observed (eight relapses or progressions (including three parenchymal CNS relapses), four residual lymphoma, and two second malignancies). The 4-year EFS was 69.6% (95% CI, 55.2 to 80.9), which did not differ from the rate observed historically (P = .59). Seven deaths occurred (six disease-related and one second malignancy). The overall survival was 84.8% (95% CI, 71.8 to 92.4). Twenty-two patients (48%) reached dose levels ≥ 4. Nonhematologic adverse events grade ≥ 3 or cardiac adverse events grade ≥ 2 occurred in 47 of 276 (17%) courses and 30 of 46 patients (65%).

CONCLUSION

DA-EPOCH-R did not improve the EFS compared with a historical control in this first prospective multisite international study of children and adolescents with PMLBL. Further studies are required to determine the optimum therapy for children and adolescents with this lymphoma.

Primary Mediastinal Large B-Cell Lymphoma in a Child Presenting With Superior Mediastinal Syndrome and Chylous Pleural and Pericardial Effusion

Primary mediastinal (thymic) large B-cell lymphoma is an aggressive B-cell lymphoma. It comprises <3% of all pediatric non-Hodgkin lymphomas (NHLs). Primary mediastinal (thymic) large B-cell lymphoma usually presents with serous pleural effusion, but presentation with chylous pleural and pericardial effusions is rare. We present a child who presented with features of a superior mediastinal syndrome. Biopsy of the mediastinal mass confirmed the diagnosis of large B-cell lymphoma. In view of nonimprovement of respiratory distress with chemotherapy and persistence of features of superior mediastinal syndrome, the child was evaluated and found to have massive pleural and pericardial effusion on imaging. Therapeutic thoracentesis and pericardiocentesis revealed chylous nature of the fluid.

Management of children and adolescents with gray zone lymphoma: A case series

BACKGROUND

Data on management of gray zone lymphoma (GZL) in children and adolescents are scarce.

PROCEDURE

This retrospective study assessed clinical characteristics and outcome in six Austrian patients with GZL less than 18 years of age (male-to-female ratio: 1:1; median age: 15.8 years).

RESULTS

Two patients each had a classical Hodgkin lymphoma (cHL)-like and composite GZL subtype, and one patient each had a large B-cell non-Hodgkin lymphoma (LBCL)-like and sequential GZL subtype. All had advanced disease with mediastinal and extranodal involvement. Five patients received an LBCL- and one patient a cHL-directed polychemotherapy ± radiotherapy. Out of the former patients, three survived, including two who relapsed and underwent high-dose chemotherapy with autologous stem cell rescue. The latter patient survived.

CONCLUSIONS

GZL remains a diagnostic and therapeutic challenge, necessitating the development of novel treatment concepts performed in a prospective setting.

Composite and sequential lymphoma between classical Hodgkin lymphoma and primary mediastinal lymphoma/diffuse large B-cell lymphoma, a clinico-pathological series of 25 cases

Composite and sequential lymphomas involving both classical Hodgkin lymphoma (CHL) and primary mediastinal B-cell lymphoma (PMBCL) are rare phenomena. Beyond the relevant biological interest raised by these cases, treatments and outcome data are poorly covered in the recent literature. This retrospective analysis describes the pathological and clinical characteristics of 10 composite and 15 sequential cases included after a central pathological review. At diagnosis, 70% of the composite lymphomas presented a disseminated and extranodal disease. Among the 15 sequential lymphomas, 12 were CHL at first occurrence and three were PMBCL. Based on their clinical evolution, these sequential lymphomas could be divided into early (i.e., diagnosis of second lymphoma within a year) and late [(i.e., a second lymphoma occurrence occurring after a long period of complete remission]). All composite cases were alive in complete remission after a median follow-up of 34 months. If the early sequential lymphoma presented a particularly poor outcome with a median overall survival shorter than one year, the late cases were efficiently salvaged. Further molecular studies are needed to describe the underlying biology of these rare diseases, possibly representing the extreme of tumour cell plasticity found in grey-zone lymphoma.

Molecular Genetics in the Diagnosis and Biology of Lymphoid Neoplasms

OBJECTIVES

The 2017 Workshop of the Society for Hematopathology/European Association for Haematopathology reviewed the role of molecular genetics in the diagnosis and biology of lymphoid neoplasms.

METHODS

The Workshop Panel reviewed 82 cases.

RESULTS

Molecular genetic testing reveals alterations that expand the spectrum of diseases such as DUSP22 rearrangement in ALK-negative anaplastic large cell lymphoma, large B-cell lymphoma with IRF4 rearrangement, MYD88 mutations in B-cell lymphomas, Burkitt-like lymphoma with 11q aberrations, and diagnostic criteria for high-grade B-cell lymphomas. Therapeutic agents and natural tumor progression may be associated with transcriptional reprogramming that lead to transdifferentiation and lineage switch.

CONCLUSIONS

Application of emerging technical advances has revealed the complexity of genetic events in lymphomagenesis, progression, and acquired resistance to therapies. They also contribute to enhanced understanding of the biology of indolent vs aggressive behavior, clonal evolution, tumor progression, and transcriptional reprogramming associated with transdifferentiation events that may occur subsequent to therapy.

Gray Zone Lymphoma Arising in the Neck of a Teenager With a Germline Mutation in TP53

Gray zone lymphoma is an aggressive disease for which appropriate management is still debated. We report a 15-year-old girl with a cervical mass, an enlarged ipsilateral tonsil, and anemia. Both sites showed hypermetabolism on F18-FG positron emission tomography/CT. Surgical resection was diagnostic of Epstein-Barr virus-negative gray zone lymphoma cervical and tonsillar involvement. No abnormality was found in cytogenetic analysis on tumor cells. However, exome sequencing in peripheral blood DNA revealed a germline mutation in TP53. Complete response was achieved after surgery and 6 cycles of rituximab with dose-adjusted etoposide, prednisone, vincristine, cyclophosphamide, and doxorubicin regimen.

Positron emission tomography-computed tomography predictors of progression after DA-R-EPOCH for PMBCL

Dose-adjusted rituximab plus etoposide, prednisone, vincristine, cyclophosphamide, and doxorubicin (DA-R-EPOCH) has produced good outcomes in primary mediastinal B-cell lymphoma (PMBCL), but predictors of resistance to this treatment are unclear. We investigated whether [¹⁸F]fluorodeoxyglucose positron emission tomography-computed tomography (PET-CT) findings could identify patients with PMBCL who would not respond completely to DA-R-EPOCH. We performed a retrospective analysis of 65 patients with newly diagnosed stage I to IV PMBCL treated at 2 tertiary cancer centers who had PET-CT scans available before and after frontline therapy with DA-R-EPOCH. Pretreatment variables assessed included metabolic tumor volume (MTV) and total lesion glycolysis (TLG). Optimal cutoff points for progression-free survival (PFS) were determined by a machine learning approach. Univariate and multivariable models were constructed to assess associations between radiographic variables and PFS. At a median follow-up of 36.6 months (95% confidence interval, 28.1-45.1), 2-year PFS and overall survival rates for the 65 patients were 81.4% and 98.4%, respectively. Machine learning-derived thresholds for baseline MTV and TLG were associated with inferior PFS (elevated MTV: hazard ratio [HR], 11.5; P = .019; elevated TLG: HR, 8.99; P = .005); other pretreatment clinical factors, including International Prognostic Index and bulky (>10 cm) disease, were not. On multivariable analysis, only TLG retained statistical significance (P = .049). Univariate analysis of posttreatment variables revealed that residual CT tumor volume, maximum standardized uptake value, and Deauville score were associated with PFS; a Deauville score of 5 remained significant on multivariable analysis (P = .006). A model combining baseline TLG and end-of-therapy Deauville score identified patients at increased risk of progression.

Mature B-NHL in children, adolescents and young adults: current therapeutic approach and emerging treatment strategies

Mature B cell lymphomas account for approximately 60% of all cases of non-Hodgkin lymphoma (NHL) in children and adolescents and includes Burkitt lymphoma (BL), diffuse large B cell lymphoma (DLBCL) and other less common histologies. The outcome for patients treated with modern regimens in resource-intensive settings is excellent. Improvements in care have been accomplished through enhanced supportive therapy, including tumour lysis management and incremental refinement of chemotherapy backbones via cooperative group clinical trials in which patients receive risk group-specific intensive chemotherapy. More recent trials have established the safety and efficacy of immunotherapy. Ongoing work is required to address the substantial burden of acute therapy-related toxicity, as well as the identification of effective therapies for those patients with relapsed and refractory disease, for whom outcomes remain very poor. In this review we will summarize the results from recent therapeutic clinical trials, describe the evidence to support the inclusion of rituximab and review the rationale for the investigation of several new categories of novel agents for mature B cell lymphomas in children and adolescents.

Lymphoma in Adolescents and Young Adults: Current Perspectives

Lymphomas in adolescents and young adults represent approximately one quarter of all cancers in this age group. Historically, adolescent and young adult cancer patients represent a unique population with diverging issues surrounding psychosocial hardships/barriers, economics, and lack of standardization of therapeutic approaches.Furthermore, the biologic differences within the adolescent and young adult population seen in various lymphoma subtypes likely play a role in overall outcomes for this group. Without an organized approach to clinical and translational research for adolescent and young adult patients within specialized treatment centers, this population may continue to experience inferior results. Here we look at the current perspectives of adolescent and young adult lymphomas with respect to disease biology, clinical characteristics, treatment, and prognosis of this unique lymphoma population.

NHL in adolescents and young adults: A unique population

Non-Hodgkin lymphoma (NHL) is a heterogeneous group of lymphoid malignancies with high incidence in adolescents and young adults (AYAs). The most common diseases include diffuse large B-cell lymphoma, anaplastic large cell lymphoma, Burkitt lymphoma, lymphoblastic lymphoma, and primary mediastinal large B-cell lymphoma. In comparison to younger children and adults, AYAs (15-39 years) with NHL present a specific set of challenges including variations in tumor biology, inconsistent treatment, pharmacodynamics, and psychosocial barriers. While survival of AYAs with NHL has improved, cure rates remain suboptimal. Incorporation of novel agents into pediatric-inspired treatment regimens specifically designed for NHL in AYAs has led to improved outcomes. Consideration of AYAs as a distinct population in the diagnosis and treatment of NHL is encouraged.

Clinicopathological features and EBV infection status of lymphoma in children and adolescents in South China: a retrospective study of 662 cases

BACKGROUND

The clinicopathological features and Epstein-Barr virus (EBV) infection status of lymphoma in children and adolescents in South China is under-researched. South China is a well-known high-incidence area of EBV-associated nasopharyngeal carcinoma.

METHODS

A cohort of 662 consecutive children and adolescents' lymphomas was retrospectively analyzed and Epstein-Barr virus encoded RNAs (EBERs) in situ hybridization was performed to detect the EBV infection.

RESULTS

The majority (501/662, 75.7%) of lymphomas in children and adolescents was Non-Hodgkin lymphoma (NHL). One hundred sixty one cases (24.3%) were Hodgkin lymphoma (HL). Of the NHL, precursor cell lymphoma, mature B-cell lymphoma and peripheral T/NK-cell lymphoma accounted for 32.0%, 41.1% and 26.9% respectively. The five common subtypes were lymphoblastic lymphoma (32.0%), Burkitt lymphoma (BL) (21.0%), anaplastic large-cell lymphoma (ALCL) (14.2%), diffuse large B-cell lymphoma (DLBCL) (13.8%) and extranodal NK/T-cell lymphoma, nasal type (ENKTCL) (6.2%). EBV infection was detected in 58.9% classical Hodgkin lymphomas (CHLs), 21.4% mature B-cell lymphomas and 52.4% peripheral T/NK-cell lymphomas. Moreover, EBV was associated with high grade NHL including ENKTCL (100.0%), BL (30.5%) and DLBCL (17.6%).

CONCLUSION

The high proportion of peripheral T/NK-cell lymphomas in children and adolescents in South China are presented in this study and compared to western countries due to the high percentage of ENKTCL. ENKTCL is firmly associated with EBV infection, while more than half of HL, a portion of BL and DLBCL are related to EBV infection. This study conclusively demonstrates that EBV infection is more prevalent in children and adolescents with lymphomas in South China compared to western countries.

Gray Zone Lymphoma: Current Diagnosis and Treatment Options

The morphology of gray zone lymphoma (GZL) is variable with tumor cells spanning the spectrum of diffuse large B-cell lymphoma (DLBCL) and classical Hodgkin lymphoma. The immunophenotype is frequently discordant. Clinically, the initial case descriptions of GZL were primarily with mediastinal presentation; however, a nonmediastinal (systemic) clinical subtype is now recognized. Patients with GZL have high relapse rates. Recommended treatment of GZL is with a DLBCL-directed regimen with consideration for consolidative radiotherapy for bulk disease. Continued biologic examination of this entity is needed and there should be exploration toward integration of novel targeted therapeutic agents into the treatment paradigm of GZL.

Mature aggressive B-cell lymphoma across age groups - molecular advances and therapeutic implications

INTRODUCTION

Mature B-cell lymphoma represents the most common type of Non-Hodgkin lymphoma, and different subtypes prevail at different patient ages. Areas covered: We review recent data on differences and commonalities in mature B-cell lymphoma occurring in adult and pediatric patients, with a special emphasis on molecular advances and therapeutic implications. To this end, we will discuss knowledge on diffuse large B-cell lymphoma and Burkitt lymphoma/leukemia, which are the most frequent subtypes in adult and pediatric patients, respectively, and on primary mediastinal B-cell lymphoma, which is a subtype of mature B-cell lymphoma occurring mainly in adolescents and young adults with a female predominance. Expert commentary: Molecular profiling has revealed molecular alterations that can be used to further classify the subtypes of mature B-cell lymphoma. These new subgroups frequently respond differentially to targeted therapeutic strategies. Future clinical trials utilizing new drugs will address this issue by combining clinical data and response assessment with a molecular workup of the corresponding lymphomas.

The immunophenotypic spectrum of primary mediastinal large B-cell lymphoma reveals prognostic biomarkers associated with outcome

Primary mediastinal large B-cell lymphoma (PMBL) is a distinct subtype of diffuse large B-cell lymphoma (DLBCL) that shows overlap with classical Hodgkin lymphoma (CHL) and a favorable prognosis compared to mediastinal gray-zone lymphoma (MGZL). We performed immunohistochemistry on initial diagnostic specimens of 49 cases of uniformly treated PMBL to determine the frequency and clinical significance of expression of antigens commonly seen in CHL and MGZL, along with markers previously shown to be prognostic in DLBCL, not otherwise specified. The median age was 37 years with a female:male ratio of 2.3. After a median follow-up of 78 months, 24% of patients had relapsed or refractory disease and 22% had died; the 5-year PFS was 70%. Variable CD15 expression was seen in 31% of cases, but was not associated with adverse outcome. Hans cell-of-origin, proliferation index, and MYC/BCL2 coexpression were not associated with outcome, while low PDL1 (P = 0.011) and high MUM1 (P = 0.065) staining were each associated with shorter PFS. A biologic risk score (one point each for low PDL1 and high MUM1) stratified patients into three prognostic risk groups for PFS (P = 0.001) and OS (P = 0.032). On separate multivariate models, low PDL1 was independent of R-IPI risk group for PFS (HR 6.0, P = 0.023), as was a biologic risk score of 2 (HR 5.6, P = 0.011). Incorporation of the biologic risk score sub-stratified patients within R-IPI groups for both PFS (P < 0.001) and OS (P < 0.001). In summary, we characterize the immunophenotypic spectrum of PMBL and identify PDL1 and MUM1 as prognostic biomarkers for high-risk disease. Am. J. Hematol. 91:E436-E441, 2016. © 2016 Wiley Periodicals, Inc.

Mediastinal Gray Zone Lymphoma

Aim. To identify aggressively behaving classical Hodgkin lymphoma (CHL) of mediastinum and primary mediastinal B-cell lymphoma (PMBCL) and to classify them as mediastinal gray zone lymphoma(MGZL) and to define a minimum immunopanel for the diagnosis of MGZL. Materials and Methods. Ninety-two mediastinal B-cell lymphomas were reviewed with a wide immunopanel and were classified as CHL, PMBCL, or MGZL. CHL with an expression of 3 or 4 transcription factors performed worse, and hence the CHL with ≥3 transcription factors were classified as MGZL-CHL. In PMBCL, the cases with a weak or negative CD20 and positive CD15 as well as those cases showing cyclin E positivity with a negative or focal LCA and any one of the transcription factors were classified as MGZL-PMBCL. Results. The MGZL cases expanded from 9 to 28 cases after using an extended immunopanel. CHL and PMBCL had a disease-free survival rate of 86.8% and 69.2% and an overall survival rate of 97.4% and 80.8%, respectively. MGZL-CHL and MGZL-PMBCL had a disease-free survival rate of 33% and 40% and an overall survival rate of 66.7% and 60%, respectively. Conclusion. Thus, the MGZL may be a wider category than we think and hence the use of a wide immunopanel is recommended to identify the aggressively behaving mediastinal B-cell lymphomas.

Identification of Primary Mediastinal Large B-cell Lymphoma at Nonmediastinal Sites by Gene Expression Profiling

Mediastinal involvement is considered essential for the diagnosis of primary mediastinal large B-cell lymphoma (PMBL). However, we have observed cases of diffuse large B-cell lymphoma (DLBCL) with features of PMBL but without detectable mediastinal involvement. The goal was to assess our previously established gene expression profiling (GEP) signature for PMBL in classifying these cases. In a large series of DLBCL cases, we identified 24 cases with a GEP signature of PMBL, including 9 cases with a submission diagnosis of DLBCL consistent with PMBL (G-PMBL-P) and 15 cases with a submission diagnosis of DLBCL. The pathology reviewers agreed with the diagnosis in the 9 G-PMBL-P cases. Among the other 15 DLBCL cases, 11 were considered to be PMBL or DLBCL consistent with PMBL, 3 were considered to be DLBCL, and 1 case was a gray-zone lymphoma with features intermediate between DLBCL and classical Hodgkin lymphoma. All 9 G-PMBL-P and 9 of the 15 DLBCL cases (G-PMBL-M) had demonstrated mediastinal involvement at presentation. Interestingly, 6 of the 15 DLBCL cases (G-PMBL-NM) had no clinical or radiologic evidence of mediastinal involvement. The 3 subgroups of PMBL had otherwise similar clinical characteristics, and there were no significant differences in overall survival. Genetic alterations of CIITA and PDL1/2 were detected in 26% and 40% of cases, respectively, including 1 G-PMBL-NM case with gain of PDL1/2. In conclusion, PMBL can present as a nonmediastinal tumor without evidence of mediastinal involvement, and GEP offers a more precise diagnosis of PMBL.

Surface Light Chain Expression in Primary Mediastinal Large B-Cell Lymphomas by Multiparameter Flow Cytometry

OBJECTIVES

Primary mediastinal large B-cell lymphoma (PMLBL) is an aggressive B-cell lymphoma typically localized to the mediastinum. To date, no study has undertaken a comprehensive analysis of this entity by multiparameter flow cytometry.

METHODS

Cases of PMLBL with diagnostic flow cytometry were identified from pathology databases of Boston Children's Hospital, Brigham and Women's Hospital, and Stanford Hospital.

RESULTS

Most of these patients with PMLBL were women with a median age of 30 years who had stage 1 disease that lacked bone marrow involvement. By flow cytometry, 50% of all PMLBLs showed restricted surface immunoglobulin expression. When comparing patients with PMLBL by the absence or presence of surface light chain immunoglobulins, no differences were seen in the morphologic appearance; expression of CD23, CD30, or CD10; age at presentation; or clinical stage (P > .5 for all). In addition, both groups showed similarly good survival outcomes and were alive at last follow-up (11/14 [79%]; P = .542).

CONCLUSIONS

This multi-institutional study demonstrates that 50% of PMLBLs can present with clonal surface light chain expression and that PMLBL is more immunophenotypically diverse than previously described. Furthermore, our findings suggest that the absence or presence of surface light chains should not be used as criteria for diagnosis in this disease.

Non-Hodgkin Lymphoma in Children and Adolescents: Progress Through Effective Collaboration, Current Knowledge, and Challenges Ahead

Non-Hodgkin lymphoma is the fourth most common malignancy in children, has an even higher incidence in adolescents, and is primarily represented by only a few histologic subtypes. Dramatic progress has been achieved, with survival rates exceeding 80%, in large part because of a better understanding of the biology of the different subtypes and national and international collaborations. Most patients with Burkitt lymphoma and diffuse large B-cell lymphoma are cured with short intensive pulse chemotherapy containing cyclophosphamide, cytarabine, and high-dose methotrexate. The benefit of the addition of rituximab has not been established except in the case of primary mediastinal B-cell lymphoma. Lymphoblastic lymphoma is treated with intensive, semi-continuous, longer leukemia-derived protocols. Relapses in B-cell and lymphoblastic lymphomas are rare and infrequently curable, even with intensive approaches. Event-free survival rates of approximately 75% have been achieved in anaplastic large-cell lymphomas with various regimens that generally include a short intensive B-like regimen. Immunity seems to play an important role in prognosis and needs further exploration to determine its therapeutic application. ALK inhibitor therapeutic approaches are currently under investigation. For all pediatric lymphomas, the intensity of induction/consolidation therapy correlates with acute toxicities, but because of low cumulative doses of anthracyclines and alkylating agents, minimal or no long-term toxicity is expected. Challenges that remain include defining the value of prognostic factors, such as early response on positron emission tomography/computed tomography and minimal disseminated and residual disease, using new biologic technologies to improve risk stratification, and developing innovative therapies, both in the first-line setting and for relapse.

Aggressive B-cell lymphomas: a review and practical approach for the practicing pathologist

Recent advances in diffuse large B-cell lymphoma are changing the way pathologists approach, diagnose, and report on this heterogeneous group of lymphomas. The purpose of this review is to provide a practical yet comprehensive approach to diffuse large B-cell lymphoma and aggressive B-cell lymphomas that can be used and easily interpreted by pathologists at all levels of training. It will address important concepts and current testing modalities which provide important prognostic information for the clinician when considering appropriate chemotherapeutic regimens for each patient's lymphoma diagnosis. It will also provide some insights into recently reported signaling pathways and molecular alterations and their contribution to lymphomagenesis and how identifying these abnormalities may provide future potential therapeutic targets for these aggressive lymphomas.

Pediatric lymphomas and histiocytic disorders of childhood

Although there have been dramatic improvements in the treatment of children with non-hodgkin lymphoma, hodgkin lymphoma and histiocytic disorders over the past 3 decades, many still relapse or are refractory to primary therapy. In addition, late effects such as 2nd malignancies, cardiomyopathy and infertility remain a major concern. Thus, this review focuses on the current state of the science and, in particular, novel treatment strategies that are aimed at improving outcomes for all pediatric patients with lymphoma and histiocytic disorders while reducing treatment related morbidity.

The histological classification of diffuse large B-cell lymphomas

Diffuse large B-cell lymphomas (DLBCLs) are aggressive B-cell neoplasms with considerable clinical, biologic, and pathologic diversity, in part reflecting the functional diversity of the B-cell system and multiple pathways of transformation. In recent years, the advent of new high-throughput genomic technologies has provided new insights into the biology of DLBCL, leading to the identification of distinct molecular identities and novel pathogenetic pathways. This increasing complexity had led to an expanding number of entities in the World Health Organization classification. Using a multi-modality approach, the updated 2008 classification delineated some new subgroups, including DLBCLs associated with particular age groups or specific anatomic sites, as well as two borderline categories (tumors at the interface between classical Hodgkin lymphoma and DLBCL as well as between Burkitt lymphoma and DLBCL). This article reviews the histopathologic features of the various aggressive B-cell lymphoma subtypes included in the 2008 classification, with emphasis on some of the new entities as well as areas of diagnostic challenge.

Pathology of B-cell lymphomas: diagnosis and biomarker discovery

The diagnosis of B-cell non-Hodgkin lymphomas has changed significantly over the past few decades as new immunophenotypic markers, molecular subtype classification schemes, and novel biomarkers have emerged. Meanwhile, there has been an increasing emphasis on individualizing treatment approaches in accordance with a biologic heterogeneity that has been uncovered within many of the individual B-cell lymphoma entities. The application of high-throughput genomic sequencing to B-cell lymphomas has yielded large amounts of valuable information. The data encompass discoveries essential to an understanding of pathogenesis, clonal or tumoral evolution, and identification of biomarkers that may be useful for prognostic or therapeutic considerations. The following review discusses several of the more common, primarily tissuebased B-cell lymphomas, with a focus on pathologic classification and certain phenotypic characteristics or genetic lesions that apply to refinement of diagnosis and therapy.

New targets for antibody therapy of pediatric B cell lymphomas

Antibody therapy has become standard of care for adult B cell lymphoma patients. It is a potentially less toxic and more targeted approach for lymphoma therapy and should therefore be applied to treat pediatric B cell lymphoma patients as well. In pediatric lymphoma patients, however, clinical experience with monoclonal antibodies is very limited. This is in part due to smaller patient numbers and very good outcome with conventional chemotherapy. In addition, pediatric patient and lymphoma biology differ significantly from that found in adults often precluding extrapolation of the adult experience to children. This review focuses on targeting pediatric B cell lymphoma with monoclonal antibody therapy. The special characteristics of B cell lymphomas found in children are reviewed and six potential new lymphoma target antigens are discussed.

Malignant hematopoietic cell lines: in vitro models for the study of primary mediastinal B-cell lymphomas

Primary mediastinal B-cell lymphoma (PMBL) is a highly aggressive disease with a unique set of biological, clinical, morphological, immunological and in particular genetic features that in the molecular era of defining lymphomas clearly distinguishes it as a separate entity from other diffuse large B-cell lymphomas (DLBCL). A precise molecular diagnosis of PMBL can be achieved by gene expression profiling. The signature gene expression profile of PMBL is more closely related to classic Hodgkin lymphoma (cHL) than to other DLBCL subgroups. A number of common genetic aberrations in PMBL and cHL further underscore their close relationship. To investigate the pathobiology of lymphomas in depth, many groups have turned to cell lines that are suitable models facilitating molecular studies and providing unique insights. For the purposes of the current perspective, we focus on four bona fide PMBL-derived cell lines (FARAGE, KARPAS-1106, MEDB-1, U-2940) that we identified and validated as such through hierarchical cluster analysis among a large collection of leukemia-lymphoma cell lines. These gene expression profiles showed that the four PMBL cell lines represent a distinct entity and are most similar to cHL cell lines, confirming derivation from a related cell type. A validated cell line resource for PMBL should assist those seeking druggable targets in this entity. This review aims to provide a comprehensive overview of the currently available cellular models for the study of PMBL.

Recurrent somatic mutations of PTPN1 in primary mediastinal B cell lymphoma and Hodgkin lymphoma

Classical Hodgkin lymphoma and primary mediastinal B cell lymphoma (PMBCL) are related lymphomas sharing pathological, molecular and clinical characteristics. Here we discovered by whole-genome and whole-transcriptome sequencing recurrent somatic coding-sequence mutations in the PTPN1 gene. Mutations were found in 6 of 30 (20%) Hodgkin lymphoma cases, in 6 of 9 (67%) Hodgkin lymphoma-derived cell lines, in 17 of 77 (22%) PMBCL cases and in 1 of 3 (33%) PMBCL-derived cell lines, consisting of nonsense, missense and frameshift mutations. We demonstrate that PTPN1 mutations lead to reduced phosphatase activity and increased phosphorylation of JAK-STAT pathway members. Moreover, silencing of PTPN1 by RNA interference in Hodgkin lymphoma cell line KM-H2 resulted in hyperphosphorylation and overexpression of downstream oncogenic targets. Our data establish PTPN1 mutations as new drivers in lymphomagenesis.

Hodgkin lymphoma: pathology, pathogenesis, and a plethora of potential prognostic predictors

Hodgkin lymphoma (HL) encompasses 2 unique clinicopathologic entities, classical Hodgkin lymphoma (CHL) (∼95% of cases) and nodular lymphocyte predominant HL (∼5% of cases). Both subtypes demonstrate a paucity of surreptitious (in CHL) neoplastic B cells within a background of reactive inflammatory cells underscoring both the relatedness of these 2 entities to each other, as well as their distinction from other types of lymphoid neoplasia. Clinically, they are primarily nodal diseases that disseminate in a predictable manner to contiguous nodal regions. The biology of HL as a whole, as well as the genetic and pathologic features that distinguish CHL from nodular lymphocyte predominant HL and other lymphomas has been the subject of a wealth of investigation in recent decades. The aim of this review is to detail the pathologic features of HL and to highlight the recent insights into its molecular basis and the myriad prognostic markers being described.

Mature B-cell lymphoma and leukemia in children and adolescents-review of standard chemotherapy regimen and perspectives

Mature B-cell non-Hodgkin lymphoma (B-NHL) comprises more than 50% of all non-Hodgkin lymphoma (NHL) in children and adolescents. Many B-NHL subtypes frequently observed in adults are rarely diagnosed in children and adolescents. In this age group, Burkitt lymphoma (BL), Burkitt leukemia or FAB L3 leukemia (B-AL), diffuse large B-cell lymphoma (DLBCL), primary mediastinal large B-cell lymphoma (PMLBL), follicular lymphoma (FL), and aggressive mature B-NHL not further classifiable (B-NHL nfc) are the most common subtypes. Diverse clinical trials demonstrated similar results of current combination chemotherapy regimens succeeding in overall survival rates of more than 80%. However, treatment-related toxicity and the poor prognosis of relapse are serious concerns. Furthermore, specific histological B-NHL subtypes are rare in children and optimal treatment is not established. New treatment modalities are urgently needed for these patient groups. Rituximab, a monoclonal antibody that is already established in the treatment of adults with mature B-NHL, demonstrated promising results in pediatric patients. The definitive role of rituximab in the treatment of children and adolescents with B-NHL needs to be evaluated in prospective controlled clinical trials. This review provides a comprehensive overview of chemotherapy regimens and the perspectives for children and adolescents with mature B-cell lymphoma and leukemia.

[Lymph node pathology - an update]

Immune suppression is a risk factor for malignant lymphoma development. Progress in medical science has increased the numbers of immunosuppressed patients due to organ transplantations or successful treatment of autoimmune diseases. Different forms of immune suppression and the respective lymphoma entities are discussed in this article. Another issue treated are gray zone lymphomas between Hodgkin's lymphoma and diffuse large B cell lymphoma. This category not only represents a diagnostic challenge but also represents more a true biological continuum.

The histological and biological spectrum of diffuse large B-cell lymphoma in the World Health Organization classification

Diffuse large B-cell lymphomas (DLBCLs) are aggressive B-cell lymphomas that are clinically, pathologically, and genetically diverse, in part reflecting the functional diversity of the B-cell system. The focus in recent years has been toward incorporation of clinical features, morphology, immunohistochemistry, and ever evolving genetic data into the classification scheme. The 2008 World Health Organization classification reflects this complexity with the addition of several new entities and variants. The discovery of distinct subtypes by gene expression profiling heralded a new era with a focus on pathways of transformation as well as a promise of more targeted therapies, directed at specific pathways. Some DLBCLs exhibit unique clinical characteristics with a predilection for specific anatomic sites; the anatomic site often reflects underlying biological distinctions. Recently, the spectrum of Epstein-Barr virus (EBV)-driven B-cell proliferations in patients without iatrogenic or congenital immunosuppression has been better characterized; most of these occur in patients of advanced age and include Epstein-Barr virus (EBV)-positive large B-cell lymphoma of the elderly. Human herpesvirus 8 is involved in the pathogenesis of primary effusion lymphoma, which can present as a "solid variant." Two borderline categories were created; one deals with tumors at the interface between classic Hodgkin lymphoma and DLBCL. The second confronts the interface between Burkitt lymphoma and DLBCL, so-called "B-cell lymphoma, unclassifiable, with features intermediate between DLBCL and Burkitt lymphoma" in the 2008 classification. Most cases harbor both MYC and BCL2 translocations and are highly aggressive. Another interesting entity is anaplastic lymphoma kinase-positive DLBCL, which renders itself potentially targetable by anaplastic lymphoma kinase inhibitors. Ongoing investigations at the genomic level, with both exome and whole-genome sequencing, are sure to reveal new pathways of transformation in the future.

Shades of gray between large B-cell lymphomas and Hodgkin lymphomas: differential diagnosis and biological implications

Hodgkin lymphomas (HLs) are neoplasms of large B cells. Two types are recognized: nodular lymphocyte predominant HL (NLPHL) and classical HL (CHL). In both types, there may be morphological and possibly biological overlap with large B-cell lymphomas (LBCLs) of non-HL types. These include nodular sclerosis CHL and primary mediastinal large B-cell lymphoma; CHL rich in lymphocytes and NLPHL; and NLPHL and T-cell/histiocyte-rich LBCL. This review covers the defining features of each of these diseases, the borderlines between them, and strategies for differential diagnosis.

Whole genome profiling and other high throughput technologies in lymphoid neoplasms--current contributions and future hopes

The development of high throughput technologies based on the knowledge of the human genome has opened the possibility to search for global genomic alterations in tumors responsible for their development and progression that may have important clinical implications. One of the major applications of this genomic knowledge has been the design of different types of microarray platforms for the analysis of DNA alterations and gene expression profiling (GEP). The main contributions of the DNA studies in lymphoid neoplasms include the definition of relatively characteristic genomic profiles for specific disease entities, the demonstration of common chromosomal alterations across entities, the identification of genes and pathways targeted by the altered chromosomal regions, and the identification of chromosomal alterations with prognostic implications. RNA GEP studies in these tumors have enhanced the molecular characterization of known entities and facilitated the recognition of new subtypes and categories of lymphoid neoplasms, the identification of new biomarkers and prognostic models, and the detection of oncogenic pathways with potential implications for targeted therapies. The recent development of the next generation sequencing (NGS) technologies and its application in lymphoid neoplasms already have provided an initial view of the complex landscape of somatic mutations in these tumors and some findings with important functional and clinical implications. This review addresses the major contributions and limitations of the microarray technologies in the understanding of lymphoid neoplasms and discusses how this knowledge may be transferred into the clinics. The initial results of the NGS studies are also presented.

Gray zone lymphoma: better treated like hodgkin lymphoma or mediastinal large B-cell lymphoma?

Although primary mediastinal large B-cell lymphoma (PMBL) and classic Hodgkin lymphoma of the nodular sclerosis type (CHL-NS) are distinct diseases, they share several clinical characteristics and biologic features. Given that, it is not surprising that there exist mediastinal lymphomas that do not fit well into either category but have clinical and morphologic features overlapping and transitional between PMBL and CHL-NS. The term mediastinal gray zone lymphoma (MGZL) has been used for these tumors, which are included in the World Health Organization classification as "B-cell lymphoma, unclassifiable, with features intermediate between diffuse large B-cell lymphoma and classic Hodgkin lymphoma." Although several studies have evaluated different therapeutic strategies in PMBL and CHL-NS, there is a paucity of prospective experience treating MGZL, given its rarity and relatively recent recognition. Historically, diseases that today would be categorized as MGZL were probably called "anaplastic large-cell lymphoma Hodgkin-like," and their outcome with standard approaches was poor, with short overall survivals. In this review-following a discussion of the biology and clinical features of MGZL, and how they compare to PMBL and CHL-NS-we outline how the treatment of PMBL and CHL-NS has evolved in recent years, and how we believe MGZL should be approached therapeutically.

Outcome and pathologic classification of children and adolescents with mediastinal large B-cell lymphoma treated with FAB/LMB96 mature B-NHL therapy

Mediastinal large B-cell lymphoma (MLBL) represents 2% of mature B-cell non-Hodgkin lymphoma in patients ≤ 18 years of age. We analyzed data from childhood and adolescent patients with stage III MLBL (n = 42) and non-MLBL DLBCL (n = 69) treated with Group B therapy in the French-American-British/Lymphome Malins de Burkitt (FAB/LMB) 96 study. MLBL patients had a male/female 26/16; median age, 15.7 years (range, 12.5-19.7); and LDH < 2 versus ≥ 2 × the upper limit of normal, 23:19. Six MLBL patients (14%) had < a 20% response to initial COP (cyclophosphamide, vincristine, and prednisone) therapy. Central pathology revealed approximately 50% with classical features of primary MLBL. Five-year event-free survival for the stage III MLBL and non-MLBL DLBCL groups was 66% (95% confidence interval [CI], 49%-78%) and 85% (95% CI, 71%-92%), respectively (P < .001; 14%). The 5-year overall survival in the 42 MLBL patients was 73% (95% CI, 56%-84%). We conclude that MLBL in adolescent patients is associated with significantly inferior event-free survival compared with stage III non-MLBL DLBCL and can be of multiple histologies. Alternate treatment strategies should be investigated in the future taking into account both adult MLBL approaches and more recent biologic findings in adult MLBL.