Mutational and transcriptional landscape of pediatric B-cell precursor lymphoblastic lymphoma.

ABSTRACT: Pediatric B-cell precursor (BCP) lymphoblastic malignancies are neoplasms with manifestation either in the bone marrow or blood (BCP acute lymphoblastic leukemia [BCP-ALL]) or are less common in extramedullary tissue (BCP lymphoblastic lymphoma [BCP-LBL]). Although both presentations are similar in morphology and immunophenotype, molecular studies have been virtually restricted to BCP-ALL so far. The lack of molecular studies on BCP-LBL is due to its rarity and restriction on small, mostly formalin-fixed paraffin-embedded (FFPE) tissues. Here, to our knowledge, we present the first comprehensive mutational and transcriptional analysis of what we consider the largest BCP-LBL cohort described to date (n = 97). Whole-exome sequencing indicated a mutational spectrum of BCP-LBL, strikingly similar to that found in BCP-ALL. However, epigenetic modifiers were more frequently mutated in BCP-LBL, whereas BCP-ALL was more frequently affected by mutation in genes involved in B-cell development. Integrating copy number alterations, somatic mutations, and gene expression by RNA sequencing revealed that virtually all molecular subtypes originally defined in BCP-ALL are present in BCP-LBL, with only 7% of lymphomas that were not assigned to a subtype. Similar to BCP-ALL, the most frequent subtypes of BCP-LBL were high hyperdiploidy and ETV6::RUNX1. Tyrosine kinase/cytokine receptor rearrangements were detected in 7% of BCP-LBL. These results indicate that genetic subtypes can be identified in BCP-LBL using next-generation sequencing, even in FFPE tissue, and may be relevant to guide treatment.

EBV-driven lymphoid neoplasms associated with pediatric ALL maintenance therapy.

The development of a second malignancy after the diagnosis of childhood acute lymphoblastic leukemia (ALL) is a rare event. Certain second malignancies have been linked with specific elements of leukemia therapy, yet the etiology of most second neoplasms remains obscure and their optimal management strategies are unclear. This is a first comprehensive report of non-Hodgkin lymphomas (NHLs) following pediatric ALL therapy, excluding stem-cell transplantation. We analyzed data of patients who developed NHL following ALL diagnosis and were enrolled in 12 collaborative pediatric ALL trials between 1980-2018. Eighty-five patients developed NHL, with mature B-cell lymphoproliferations as the dominant subtype (56 of 85 cases). Forty-six of these 56 cases (82%) occurred during or within 6 months of maintenance therapy. The majority exhibited histopathological characteristics associated with immunodeficiency (65%), predominantly evidence of Epstein-Barr virus-driven lymphoproliferation. We investigated 66 cases of post-ALL immunodeficiency-associated lymphoid neoplasms, 52 from our study and 14 additional cases from a literature search. With a median follow-up of 4.9 years, the 5-year overall survival for the 66 patients with immunodeficiency-associated lymphoid neoplasms was 67.4% (95% confidence interval [CI], 56-81). Five-year cumulative risks of lymphoid neoplasm- and leukemia-related mortality were 20% (95% CI, 10.2-30) and 12.4% (95% CI, 2.7-22), respectively. Concurrent hemophagocytic lymphohistiocytosis was associated with increased mortality (hazard ratio, 7.32; 95% CI, 1.62-32.98; P = .01). A large proportion of post-ALL lymphoid neoplasms are associated with an immunodeficient state, likely precipitated by ALL maintenance therapy. Awareness of this underrecognized entity and pertinent diagnostic tests are crucial for early diagnosis and optimal therapy.

Non-Hodgkin lymphoma presenting with spinal cord compression: A population-based analysis of the NHL-BFM study group.

BACKGROUND: Spinal cord compression is a rare presentation of non-Hodgkin lymphoma (NHL) in children. We aimed to describe the prevalence, histological subtypes, clinical presentation, therapy, and outcome of those children in a population-based cohort. The chemotherapy regimen remained comparable over time. METHODS: We retrospectively identified all children and adolescents with paresis as initial manifestations of the NHL between January 1990 and December 2020 from the NHL-BFM database. Characteristics, therapy, and outcome data were gathered from the database and patient files. RESULTS: Fifty-seven of 4779 children (1.2%) presented with initial paresis due to spinal cord compression. The median age was 10.3 years (range, 3.1-18.0 years), and 33% were female. Initial symptoms were paresis/weakness (n = 50, 88%), back pain (n = 33, 58%), paresthesia (n = 23, 40%), and bladder dysfunction and/or constipation (n = 22, 39%), persisting for a median of 14 days before diagnosis. Subtype distribution was mature B-NHL (n = 41, 72%), precursor B-lymphoblastic lymphoma (LBL) (n = 12, 21%), anaplastic large cell lymphoma (ALCL) (n = 3, 5%), and T-LBL (n = 1, 2%). Initial emergency therapy included surgery (70%) and/or chemotherapy/steroids (63%). Five-year event-free survival and overall survival (80% ± 5% and 82% ± 5%, respectively) were comparable with all other NHL patients. Neurological symptoms persisted in approximately one-third of surviving patients at the last follow-up. CONCLUSION: 1.2% of pediatric NHL patients presented with paresis from spinal cord compression mainly due to B-cell lymphomas. Neurological sequelae were observed in one-third of surviving patients.

Stopping antibacterial prophylaxis in pediatric allogeneic hematopoietic cell transplantation: An internal audit.

BACKGROUND: Antibacterial prophylaxis in children and adolescents undergoing allogeneic hematopoietic cell transplantation (HCT) is controversial and not recommended by international guidelines. We analyzed relevant posttransplant outcomes following discontinuation of antibacterial prophylaxis at a major European pediatric transplant center. METHODS: The single-center retrospective audit included all pediatric allogeneic HCT patients (pts) transplanted between 2011 and 2020 before (≤2014) and after (≥2015) stopping routine antibacterial prophylaxis with penicillin, metronidazole, and ciprofloxacin upon start of the conditioning regimen. The primary endpoint was overall survival until the first hospital discharge. Secondary endpoints included the occurrence of fever; bacterial infections; and cumulative days with antibacterial agents until discharge. RESULTS: A total of 257 HCT procedures were performed in 249 pts (median age: 10 years, range, 0.2-22.5) for leukemia/lymphoma (n = 150) and nonmalignant disorders (n = 107). Of these, 104 procedures were performed before (cohort 1) and 153 after (cohort 2) stopping prophylaxis. Overall survival until discharge was 90.4% in cohort 1 and 96.1% in cohort 2 (p = .06). No differences were observed in the occurrence of fever (92.3 vs. 94.1%; p = .57) and bacterial infections (34.6 vs. 25.5%; p = .11). The median number of days on antibacterial agents was significantly lower in cohort 2 (39 vs. 34; p = .002). Detection rates of resistant organisms were overall low. CONCLUSION: In this single-center audit, the stop of routine antibacterial prophylaxis had no effect on the occurrence of fever, bacterial infections, resistant organisms, and GVHD. Overall antibiotic use was significantly reduced, and survival was noninferior to the historical control cohort.

The landscape of genomic alterations across childhood cancers.

Pan-cancer analyses that examine commonalities and differences among various cancer types have emerged as a powerful way to obtain novel insights into cancer biology. Here we present a comprehensive analysis of genetic alterations in a pan-cancer cohort including 961 tumours from children, adolescents, and young adults, comprising 24 distinct molecular types of cancer. Using a standardized workflow, we identified marked differences in terms of mutation frequency and significantly mutated genes in comparison to previously analysed adult cancers. Genetic alterations in 149 putative cancer driver genes separate the tumours into two classes: small mutation and structural/copy-number variant (correlating with germline variants). Structural variants, hyperdiploidy, and chromothripsis are linked to TP53 mutation status and mutational signatures. Our data suggest that 7-8% of the children in this cohort carry an unambiguous predisposing germline variant and that nearly 50% of paediatric neoplasms harbour a potentially druggable event, which is highly relevant for the design of future clinical trials.

Author Correction: The landscape of genomic alterations across childhood cancers.

In this Article, author Benedikt Brors was erroneously associated with affiliation number '8' (Department of Developmental Neurobiology, St Jude Children's Research Hospital, Memphis, Tennessee, USA); the author's two other affiliations (affiliations '3' and '7', both at the German Cancer Research Center (DKFZ)) were correct. This has been corrected online.

Integrative genomic analysis of pediatric T-cell lymphoblastic lymphoma reveals candidates of clinical significance.

T-cell lymphoblastic lymphoma (T-LBL) is a heterogeneous malignancy of lymphoblasts committed to T-cell lineage. The dismal outcomes (15%-30%) after T-LBL relapse warrant establishing risk-based treatment. To our knowledge, this study presents the first comprehensive, systematic, integrated, genome-wide analysis including relapsed cases that identifies molecular markers of prognostic relevance for T-LBL. NOTCH1 was identified as the putative driver for T-LBL. An activated NOTCH/PI3K-AKT signaling axis and alterations in cell cycle regulators constitute the core oncogenic program for T-LBL. Mutated KMT2D was identified as a prognostic marker. The cumulative incidence of relapse was 47% ± 17% in patients with KMT2D mutations, compared with 14% ± 3% in wild-type KMT2D. Structural analysis of the mutated domains of KMT2D revealed a plausible impact on structure and functional consequences. These findings provide new insights into the pathogenesis of T-LBL, including high translational potential. The ongoing LBL 2018 trial (www.clinicaltrials.gov #NCT04043494) allows for prospective validation and subsequent fine tuning of the stratification criteria for T-LBL risk groups to improve survival of pediatric patients.

18 F-FDG-PET/CT imaging in diagnostic workup of pediatric precursor B-cell lymphoblastic lymphoma.

18 F-fluorodeoxyglucose-positron emission tomography/computed tomography (PET/CT) imaging is currently not used in standard diagnostics for B-cell precursor lymphoblastic lymphoma (BCP-LBL), and it is unknown whether PET/CT imaging would lead to agreement between detection of lesions with the gold standard imaging methods. Therefore, we performed a retrospective cohort study in which we included 32 pediatric BCP-LBL patients and determined localizations by reviewing local imaging reports. There was a disagreement between protocol-based imaging and PET/CT in 59% of the patients, and the discrepancies mostly comprise of additional lesions detected with PET/CT, typically in lymph node and bone or the absence of bone marrow involvement with PET/CT. If PET/CT was leading in determining definite stage of disease, this would lead to a different stage and therapy branch in 31% and 28% of the patients, respectively.

Parvovirus B19 infection in pediatric allogeneic hematopoietic cell transplantation - Single-center experience and review.

BACKGROUND: Parvovirus B19 (B19V) infection following pediatric hematopoietic cell transplantation (HCT) is a rare complication and available data is scarce. Therefore, we present the experience with B19V Infection in allogeneic pediatric HCT recipients at our transplant center together with a systematic review of the literature. METHODS: Pediatric HCT patients with Parvovirus B19 infection treated at the University Children's Hospital Münster between 1999 and 2021 were retrospectively identified and clinical data were analyzed. Additionally, a systematic MEDLINE search to identify relevant articles was performed. RESULTS: We identified three out of 445 patients (0.6%) with B19V infection post-transplantation. B19V infection occurred in combination with other complications like Graft-versus-Host disease, additional infections, or autoimmune-mediated hemolysis potentially triggered by B19V. In one patient these complications lead to a fatal outcome. The review of the literature showed considerable morbidity of B19V infection with the potential for life-threatening complications. Most patients were treated by red blood cell transfusion and intravenous immunoglobulins (IVIG) with a high succession rate. CONCLUSION: Symptomatic B19V infection following HCT remains a rare but potentially challenging complication. A causal antiviral therapy does not exist as well as general recommendations on dosage and duration of IVIG therapy. Despite this, most patients are treated successfully with these measures. Additionally, transmission via blood or stem cell products is also rare and no general recommendations on B19V screenings exist.

Design of a targeted next-generation DNA sequencing panel for pediatric T-cell lymphoblastic lymphoma to unravel biology and optimize treatment.

Low incidence and molecular heterogeneity of pediatric T-cell lymphoblastic lymphoma (T-LBL) require an international, large-scale effort to identify novel clinical biomarkers. The ongoing international clinical trial LBL2018 (NCT04043494) represents an ideal opportunity to implement a common analytic approach. Targeted next-generation sequencing is well-suited for this purpose; however, selection of relevant target genes for T-LBL remains subject of ongoing debates. Our group has recently designed and evaluated a first target panel of 80 candidate genes for T-LBL. The present study aimed at developing a novel optimized gene panel for large-scale application and to promote an international agreement on a common core panel. Small sequence variants obtained from our former study were systematically analyzed and classified with regards to pathogenic relevance, to prioritize candidate genes. Additional genes were curated from literature and online databases for a more comprehensive analysis of relevant functions and signaling pathways. The new target panel TGP-T-LBL entails 84 candidate genes which are key actors in NOTCH, PI3K-AKT, JAK-STAT, RAS signaling, epigenetic regulation, transcription, DNA repair, cell cycle regulation, and ribosomal function. From our former gene panel, 35 out of 80 candidate genes were selected for the novel panel. Forty-six out of 84 genes are currently being analyzed in the ongoing international trial LBL2018. Exploratory analysis of prognostic relevance on mutation-level suggested a potential association of PIK3CA variants c.1624G>A(p.Glu542Lys) and c.1633G>A(p.Glu545Lys) to occurrence of relapse, emphasizing particular relevance of mutation analysis in PI3K-AKT signaling. Our approach promotes comprehensive and clinically relevant mutational profiling of pediatric T-LBL.

Epstein-Barr virus status of sporadic Burkitt lymphoma is associated with patient age and mutational features.

Sporadic Burkitt lymphoma (BL) is the most frequent tumour of children and adolescents but a rare subtype of lymphomas in adults. To date most molecular data have been obtained from lymphomas arising in the young. Recently, Epstein-Barr virus (EBV) positive and negative BL in young patients was shown to differ in molecular features. In the present study, we present a large age-overarching cohort of sporadic BL (n = 162) analysed by immunohistochemistry, translocations of MYC proto-oncogene, basic helix-loop-helix transcription factor (MYC), B-cell leukaemia/lymphoma 2 (BCL2) and B-cell leukaemia/lymphoma 6 (BCL6) and by targeted sequencing. We illustrate an age-associated inter-tumoral molecular heterogeneity in this disease. Mutations affecting inhibitor of DNA binding 3, HLH protein (ID3), transcription factor 3 (TCF3) and cyclin D3 (CCND3), which are highly recurrent in paediatric BL, and expression of sex determining region Y-box transcription factor 11 (SOX11) declined with patient age at diagnosis (P = 0·0204 and P = 0·0197 respectively). In contrast, EBV was more frequently detected in adult patients (P = 0·0262). Irrespective of age, EBV-positive sporadic BL showed significantly less frequent mutations in ID3/TCF3/CCND3 (P = 0·0088) but more often mutations of G protein subunit alpha 13 (GNA13; P = 0·0368) and forkhead box O1 (FOXO1; P = 0·0044) compared to EBV-negative tumours. Our findings suggest that among sporadic BL an EBV-positive subgroup of lymphomas increases with patient age that shows distinct pathogenic features reminiscent of EBV-positive endemic BL.

Progressive or relapsed Burkitt lymphoma or leukemia in children and adolescents after BFM-type first-line therapy.

Children with refractory or relapsed Burkitt lymphoma (BL) or Burkitt leukemia (B-AL) have a poor chance to survive. We describe characteristics, outcome, reinduction, and transplantation approaches and evaluate risk factors among children with progression of a BL/B-AL included in Non-Hodgkin's Lymphoma-Berlin-Frankfurt-Münster studies between 1986 and 2016. Treatment recommendation was reinduction including rituximab from the early 2000s followed by blood stem cell transplantation. The 3-year survival of the 157 children was 18.5 ± 3%. Survival significantly improved from 11 ± 3% before to 27 ± 5% after 2000 (P < .001), allowing for risk factor analyses among the latter 75 patients. Survival of 14 patients with relapse after initial therapy for low-risk disease (R1/R2) was 50 ± 13% compared with 21 ± 5% for 61 patients progressing after R3/R4 therapy (P < .02). A total of 25 of 28 patients with progression during first-line therapy, 31 of 32 with progression during reinduction, 15 of 16 not reaching a complete remission (CR) before transplantation, 9 of 10 treated with rituximab front-line, and all 13 patients not receiving rituximab during reinduction died. Forty-six patients received stem cell transplantation (20 autologous, 26 allogeneic). Survival after a regimen combining rituximab with continuous-infusion chemotherapy followed by allogeneic transplantation was 67 ± 12% compared with 18 ± 5% for all other regimen and transplantations (P = .003). Patients with relapsed BL/B-AL have a poor chance to survive after current effective front-line therapies. Progression during initial or reinduction chemotherapy and initial high-risk disease are risk factors in relapse. Time-condensed continuous-infusion reinduction followed by stem cell transplantation forms the basis for testing new drugs.

Patient parameters and response after administration of rituximab in pediatric mature B-cell non-Hodgkin lymphoma.

BACKGROUND: Mature aggressive B-cell lymphomas are heterogenous malignancies that make up more than half of all diagnosed non-Hodgkin lymphoma in children and adolescents. The overall survival rate increased over the last decades to 80%-90% due to fine tuning of polychemotherapy. However, new therapeutic implications are needed to further increase the overall survival. Current clinical trials analyze the therapeutic effect of rituximab in pediatric patients, while the mechanism of action in vivo is still not fully understood. METHODS: Effector molecules important for tumor defense were analyzed before and at day 5 after rituximab treatment via flow cytometry. Serum rituximab levels were measured with an ELISA. RESULTS: We evaluated patient parameters that may affect treatment response in relation to rituximab administration and serum rituximab levels. We indeed found a reduction of Fcγ receptor (FcγR) II levels after rituximab treatment in monocyte subtypes, whereas FcγRI expression was significantly increased. Serum levels of proinflammatory marker proteins S100A8/A9 and S100A12 significantly decreased after treatment to normal levels from an overall proinflammatory state before treatment. CD57, perforin, and granzyme B expression decreased after treatment, comprising a less cytolytic natural killer (NK) cell population. CONCLUSION: The highlighted effects of rituximab treatment on patient's immune response help in understanding the biology behind tumor defense mechanisms and effector function. After subsequent studies, these novel insights might be translated into patient care and could contribute to improve treatment of pediatric patients with mature aggressive B-cell lymphoma.

[Teacher's Health Promotion - Participation in Health-Promoting Interventions in the School Setting]. / Gesundheitsförderung für Lehrkräfte ­ Inanspruchnahme von gesundheitsförderlichen Maßnahmen im Setting Schule.

AIM: This study examined the participation in health-promoting measures by teachers and the perceived fit between offers and subjective needs from the teachers' perspective. METHODS: In the academic year 2017/18, questionnaire-based data were collected at schools in the German state of Brandenburg (n=830). The teachers answered questions about the use, offer and subjective need regarding health-promoting measures. RESULTS: 81.3% of teachers had participated in one or more health-promoting measures in the past 24 months. We found no significant differences in age, gender, type and sponsorship of school. In most subjects of health promotion, teachers indicated a considerably higher need for such measures compared to the perceived offer. From the teachers' point of view, there was a particular need for measures to change individual behavior and the health-promoting design of the schools and classrooms. CONCLUSION: When implementing prevention measures, the fit between offers and subjective needs from the teachers' point of view should be given greater consideration.

Primary post-transplant lymphoproliferative disorder of the central nervous system: characteristics, management and outcome in 25 paediatric patients.

Primary central nervous system (CNS) post-transplant lymphoproliferative disorder (PTLD) in childhood is rare. Twenty-five patients were retrieved from nine European Intergroup for Childhood Non-Hodgkin's Lymphoma and/or international Berlin-Frankfurt-Münster Study Group members. Types of allografts included kidney (n = 11), liver (n = 4), heart (n = 5), bowel (n = 1) and haematopoietic stem cells (n = 4). Eighteen were male, 16 ≥ 10 years old, 21 had monomorphic disease and 24 solid intracranial tumour masses. Four-year event-free and overall survival rates were 50% ± 10% and 74% ± 9% respectively. This report represents the largest paediatric series of CNS PTLD reported to date, showing favourable survival odds following systemic and intrathecal chemotherapy and rituximab administration.

The mutational landscape of Burkitt-like lymphoma with 11q aberration is distinct from that of Burkitt lymphoma.

The new recently described provisional lymphoma category Burkitt-like lymphoma with 11q aberration comprises cases similar to Burkitt lymphoma (BL) on morphological, immunophenotypic and gene-expression levels but lacking the IG-MYC translocation. They are characterized by a peculiar imbalance pattern on chromosome 11, but the landscape of mutations is not yet described. Thus, we investigated 15 MYC-negative Burkitt-like lymphoma with 11q aberration (mnBLL,11q,) cases by copy-number analysis and whole-exome sequencing. We refined the regions of 11q imbalance and identified the INO80 complex-associated gene NFRKB as a positional candidate in 11q24.3. Next to recurrent gains in 12q13.11-q24.32 and 7q34-qter as well as losses in 13q32.3-q34, we identified 47 genes recurrently affected by protein-changing mutations (each ≥3 of 15 cases). Strikingly, we did not detect recurrent mutations in genes of the ID3-TCF3 axis or the SWI/SNF complex that are frequently altered in BL, or in genes frequently mutated in germinal center-derived B-cell lymphomas like KMT2D or CREBBP An exception is GNA13, which was mutated in 7 of 15 cases. We conclude that the genomic landscape of mnBLL,11q, differs from that of BL both at the chromosomal and mutational levels. Our findings implicate that mnBLL,11q, is a lymphoma category distinct from BL at the molecular level.

Second malignancies after treatment of childhood non-Hodgkin lymphoma: a report of the Berlin-Frankfurt-Muenster study group.

Second malignant neoplasms pose a concern for survivors of childhood cancer. We evaluated incidence, type and risk factors for second malignant neoplasms in patients included in Berlin-Frankfurt-Muenster protocols for childhood non-Hodgkin lymphoma. 3590 patients <15 years of age at diagnosis registered between 01/1981 and 06/2010 were analyzed. Second malignant neoplasms were reported by the treating institutions and the German Childhood Cancer Registry. After median follow-up of 9.4 years (Quartile, Q1 6.7 and Q3 12.1) 95 second malignant neoplasms were registered (26 carcinomas including 9 basal cell carcinomas, 21 acute myeloid leukemias/myelodysplastic syndromes, 20 lymphoid malignancies, 12 CNS-tumors, and 16 other). Cumulative incidence at 20 years was 5.7±0.7%, standard incidence ratio excluding basal cell carcinomas was 19.8 (95% CI 14.5-26.5). Median time from initial diagnosis to second malignancy was 8.7 years (range: 0.2-30.3). Acute-lymphoblastic-leukemia-type therapy, cumulative anthracycline dose, and cranial radiotherapy for brain tumor-development were significant risk factors in univariate analysis only. In multivariate analysis including risk factors significant in univariate analysis, female sex (HR 1.87, 95% CI 1.23-2.86, p=0.004), CNS-involvement (HR 2.24, 95% CI 1.03-4.88, p=0.042), lymphoblastic lymphoma (HR 2.60, 95% CI 1.69-3.97, p<0.001), and cancer-predisposing condition (HR 11.2, 95% CI 5.52-22.75, p<0.001) retained an independent risk. Carcinomas were the most frequent second malignant neoplasms after non-Hodgkin lymphoma in childhood followed by acute myeloid leukemia and lymphoid malignancies. Female sex, lymphoblastic lymphoma, CNS-involvement, or/and known cancer-predisposing condition were risk factors for second malignant neoplasm-development. Our findings set the basis for individualized long-term follow-up and risk assessment of new therapies.

Molecular features of non-anaplastic peripheral T-cell lymphoma in children and adolescents.

Non-anaplasticperipheral T-cell lymphomas (PTCL) are rare tumors in children, adolescents, and young adults (CAYA) with poor prognosis and scarce genetic data. We analyzed lymphoma tissue from 36 patients up to 18 years old with PTCL, not otherwise specified (PTCL-NOS), hepatosplenic T-cell lymphoma, Epstein-Barr virus (EBV)-positive T-lymphoproliferative diseases, subcutaneous panniculitis-like T-cell lymphoma, and other PTCL types. Twenty-three patients (64%) had at least one genetic variant detectable, including TET2, KMT2C, PIK3D, and DMNT3A. TP53 and RHOA variants, commonly found in adults, were not identified. Eight of 20 (40%) CAYA PTCL-NOS had no detectable mutations. The genetic findings suggest that CAYA PTCL differ from adult cases.

Experience with provisional WHO-entities large B-cell lymphoma with IRF4-rearrangement and Burkitt-like lymphoma with 11q aberration in paediatric patients of the NHL-BFM group.

Large B-cell lymphoma with IRF4 rearrangement, and Burkitt-like lymphoma with 11q aberration are two provisional lymphoma entities in the 2017 revision of the WHO classification of lymphoid neoplasms. Despite being more frequent in young patients, knowledge regarding their true incidence and clinical features in unselected cohorts of paediatric and adolescent patients is limited. We screened for both entities among paediatric patients (<18 years of age) in the German NHL-BFM (Non-Hodgkin lymphoma Berlin-Frankfurt-Münster) group. Among follicular lymphomas and diffuse large B-cell lymphomas (DLBCL), 7/34 cases (21%) showed an IRF4 break-apart pattern by fluorescence in situ hybridisation (FISH) and are associated with stages I and II disease (P = 0·043). Among lymphomas morphologically resembling Burkitt lymphoma, DLBCL and high-grade B-cell lymphoma, unclassifiable, 13/102 cases (13%) lacked a MYC break-apart pattern but were positive for 11q proximal gain and telomeric loss by FISH. MYC-negative Burkitt-like lymphomas with the typical 11q gain-loss pattern by FISH were older (P = 0·004), showed less male predominance (P = 0·003), lower stage (P = 0·040), lower serum LDH level (P = 0·01) and less abdominal involvement (P = 0·008) compared to high grade B-cell lymphomas without 11q gain-loss pattern. Both entities showed excellent outcome with overall survival of 100% when managed according to NHL-BFM strategies and may provide candidates for future therapy de-escalation in clinical trials.

IG-MYC + neoplasms with precursor B-cell phenotype are molecularly distinct from Burkitt lymphomas.

The WHO Classification of Tumours of Haematopoietic and Lymphoid Tissue notes instances of Burkitt lymphoma/leukemia (BL) with IG-MYC rearrangement displaying a B-cell precursor immunophenotype (termed herein "preBLL"). To characterize the molecular pathogenesis of preBLL, we investigated 13 preBLL cases (including 1 cell line), of which 12 were analyzable using genome, exome, and targeted sequencing, imbalance mapping, and DNA methylation profiling. In 5 patients with reads across the IG-MYC breakpoint junctions, we found evidence that the translocation derived from an aberrant VDJ recombination, as is typical for IG translocations arising in B-cell precursors. Genomic changes like biallelic IGH translocations or VDJ rearrangements combined with translocation into the VDJ region on the second allele, potentially preventing expression of a productive immunoglobulin, were detected in 6 of 13 cases. We did not detect mutations in genes frequently altered in BL, but instead found activating NRAS and/or KRAS mutations in 7 of 12 preBLLs. Gains on 1q, recurrent in BL and preB lymphoblastic leukemia/lymphoma (pB-ALL/LBL), were detected in 7 of 12 preBLLs. DNA methylation profiling showed preBLL to cluster with precursor B cells and pB-ALL/LBL, but apart from BL. We conclude that preBLL genetically and epigenetically resembles pB-ALL/LBL rather than BL. Therefore, we propose that preBLL be considered as a pB-ALL/LBL with recurrent genetic abnormalities.