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Kabuki syndrome is a well-recognized syndrome characterized by facial dysmorphism and developmental delay/intellectual disability and in the majority of patients a germline variant in KMT2D is found. As somatic KMT2D variants can be found in 5–10% of tumors a tumor predisposition in Kabuki syndrome is discussed. So far less than 20 patients with Kabuki syndrome and a concomitant malignancy have been published. Here we report on a female patient with Kabuki syndrome and a c.2558_2559delCT germline variant in KMT2D who developed an embryonal rhabdomyosarcoma (ERMS) at 10 years. On tumor tissue we performed DNA-methylation profiling and exome sequencing (ES). Copy number analyses revealed aneuploidies typical for ERMS including (partial) gains of chromosomes 2, 3, 7, 8, 12, 15, and 20 and 3 focal deletions of chromosome 11p. DNA methylation profiling mapped the case to ERMS by a DNA methylation-based sarcoma classifier. Sequencing suggested gain of the wild-type KMT2D allele in the trisomy 12. Including our patient literature review identified 18 patients with Kabuki syndrome and a malignancy. Overall, the landscape of malignancies in patients with Kabuki syndrome was reminiscent of that of the pediatric population in general. Histopathological and molecular data were only infrequently reported and no report included next generation sequencing and/or DNA-methylation profiling. Although we found no strong arguments pointing towards KS as a tumor predisposition syndrome, based on the small numbers any relation cannot be fully excluded. Further planned studies including profiling of additional tumors and long term follow-up of KS-patients into adulthood could provide further insights.

B cells have the unique property to somatically alter their immunoglobulin (IG) genes by V(D)J recombination, somatic hypermutation (SHM) and class-switch recombination (CSR). Aberrant targeting of these mechanisms is implicated in lymphomagenesis, but the mutational processes are poorly understood. By performing whole genome and transcriptome sequencing of 181 germinal center derived B-cell lymphomas (gcBCL) we identified distinct mutational signatures linked to SHM and CSR. We show that not only SHM, but presumably also CSR causes off-target mutations in non-IG genes. Kataegis clusters with high mutational density mainly affected early replicating regions and were enriched for SHM- and CSR-mediated off-target mutations. Moreover, they often co-occurred in loci physically interacting in the nucleus, suggesting that mutation hotspots promote increased mutation targeting of spatially co-localized loci (termed hypermutation by proxy). Only around 1% of somatic small variants were in protein coding sequences, but in about half of the driver genes, a contribution of B-cell specific mutational processes to their mutations was found. The B-cell-specific mutational processes contribute to both lymphoma initiation and intratumoral heterogeneity. Overall, we demonstrate that mutational processes involved in the development of gcBCL are more complex than previously appreciated, and that B cell-specific mutational processes contribute via diverse mechanisms to lymphomagenesis. This study has been supported by the German Ministry of Science and Education (BMBF) in the framework of the ICGC MMML-Seq project (01KU1002A-J) the MMML-MYC-SYS project (036166B) and the project ICGC DE-MINING (01KU1505E), the European Union in the framework of the BLUEPRINT Project (HEALTH-F5-2011-282510) and the KinderKrebsInitiative Buchholz/Holm-Seppensen. This work was supported by the BMBF-funded Heidelberg Center for Human Bioinformatics (HD-HuB) within the German Network for Bioinformatics Infrastructure (de.NBI) (#031A537A, #031A537C). Former grant support of MMML by the Deutsche Krebshilfe (2003–2011) is gratefully acknowledged. We acknowledge COSMIC and use of Cancer Gene Census. Part of the work was performed in association with SFB1074 (particularly subproject B1) funded by DFG. We wish to thank Barbara Hutter, Ivo Buchhalter, Zuguang Gu, and Natalie Jäger for skillful technical assistance. We thank the High-Throughput Sequencing Unit of the Genome and Proteome Core Facility and the Omics IT and Data Management Core Facility of the German Cancer Research Center (DKFZ, Heidelberg) as well as the Institute of Clinical Molecular Biology (IKMB, Christian-Albrechts-University Kiel) for excellent technical support and expertise. DH is a member of the Hartmut Hoffmann-Berling International Graduate School of Molecular and Cellular Biology (HBIGS) and of the MD/PhD-program of the University of Heidelberg. KK and UHT are funded by the Helmholtz International Graduate School for Cancer Research at the German Cancer Research Center. SHB, HK, and SH acknowledge support by LIFE (Leipzig Research Center for Civilization Diseases), Leipzig University. LIFE is funded by the European Union, the European Regional Development Fund (ERDF), the European Social Fund (ESF), and the Free State of Saxony. This work has been carried out with the help of the Interdisciplinary Bank of Biomaterials and Data of the University Hospital of Würzburg and the Julius Maximilian University of Würzburg (idbw). Peer Reviewed "Article signat per 70 autors/es:Daniel Hübschmann, Kortine Kleinheinz, Rabea Wagener, Stephan H. Bernhart, Cristina López, Umut H. Toprak, Stephanie Sungalee, Naveed Ishaque, Helene Kretzmer, Markus Kreuz, Sebastian M. Waszak, Nagarajan Paramasivam, Ole Ammerpohl, Sietse M. Aukema, Renée Beekman, Anke K. Bergmann, Matthias Bieg, Hans Binder, Arndt Borkhardt, Christoph Borst, Benedikt Brors, Philipp Bruns, Enrique Carrillo de Santa Pau, Alexander Claviez, Gero Doose, Andrea Haake, Dennis Karsch, Siegfried Haas, Martin-Leo Hansmann, Jessica I. Hoell, Volker Hovestadt, Bingding Huang, Michael Hummel, Christina Jäger-Schmidt, Jules N. A. Kerssemakers, Jan O. Korbel, Dieter Kube, Chris Lawerenz, Dido Lenze, Joost H. A. Martens, German Ott, Bernhard Radlwimmer, Eva Reisinger, Julia Richter, Daniel Rico, Philip Rosenstiel, Andreas Rosenwald, Markus Schillhabel, Stephan Stilgenbauer, Peter F. Stadler, José I. Martín-Subero, Monika Szczepanowski, Gregor Warsow, Marc A. Weniger, Marc Zapatka, Alfonso Valencia, Hendrik G. Stunnenberg, Peter Lichter, Peter Möller, Markus Loeffler, Roland Eils, Wolfram Klapper, Steve Hoffmann, Lorenz Trümper, ICGC MMML-Seq consortium, ICGC DE-Mining consortium, BLUEPRINT consortium, Ralf Küppers, Matthias Schlesner & Reiner Siebert"

The etiology of nonimmune hydrops fetalis is extensive and includes genetic disorders. We describe a term-born female neonate with late onset extensive nonimmune hydrops, that is, polyhydramnios, edema, and congenital bilateral chylothorax. This newborn was successfully treated with repetitive thoracocentesis, total parenteral feeding, octreotide intravenously and finally surgical pleurodesis and corticosteroids. A genetic cause seemed plausible as the maternal history revealed a fatal nonimmune hydrops fetalis. A homozygous truncating variant inGDF2(c.451C>T, p.(Arg151*)) was detected with exome sequencing. Genetic analysis of tissue obtained from the deceased fetal sibling revealed the same homozygous variant. The parents and two healthy siblings were heterozygous for theGDF2variant. Skin and lung biopsies in the index patient, as well as the revised lung biopsy of the deceased fetal sibling, showed lymphatic dysplasia and lymphangiectasia. To the best of our knowledge, this is the first report of an association between a homozygous variant inGDF2with lymphatic dysplasia, hydrothorax and nonimmune hydrops fetalis.

Chromosomal breakpoints involving the MYC gene locus, frequently referred to as MYC rearrangements (MYC - R+), are a diagnostic hallmark of Burkitt lymphoma and recurrent in many other subtypes of B-cell lymphomas including follicular lymphoma, diffuse large B-cell lymphoma and other high-grade B-cell lymphomas and are associated with an aggressive clinical course. In remarkable contrast, in MCL, only few MYC - R+ cases have yet been described. In the current study, we have retrospectively analysed 16 samples (MYC - R+, n = 15, MYC - R-, n = 1) from 13 patients and describe their morphological, immunophenotypic and (molecular) genetic features and clonal evolution patterns. Thirteen out of fifteen MYC - R+ samples showed a non-classical cytology including pleomorphic (centroblastic, immunoblastic), anaplastic or blastoid. MYC translocation partners were IG-loci in 4/11 and non-IG loci in 7/11 analysed cases. The involved IG-loci included IGH in 3 cases and IGL in one case. PAX5 was the non-IG partner in 2/7 patients. The MYC - R+ MCL reported herein frequently displayed characteristics associated with an aggressive clinical course including high genomic-complexity (6/7 samples), frequent deletions involving the CDKN2A locus (7/10 samples), high Ki-67 proliferation index (12/13 samples) and frequent P53 expression (13/13 samples). Of note, in 4/14 samples, SOX11 was not or only focally expressed and 3/13 samples showed focal or diffuse TdT-positivity presenting a diagnostic challenge as these features could point to a differential diagnosis of diffuse large B-cell lymphoma and/or lymphoblastic lymphoma/leukaemia.

Currently, prediction of time to treatment failure (TTF) and overall survival (OS) in mantle cell lymphoma (MCL) is based on the clinical factors included in the Mantle Cell Lymphoma International Prognostic Index (MIPI), and proliferation is assessed by Ki67. However, TP53 and SOX11 immunohistochemistry might improve risk stratification. We performed SOX11 and TP53 immunohistochemistry on the so far largest published cohort of lymphoma specimens (n = 365). All patients were treated in prospective trials of the European MCL Network. In multivariate analyses, including MIPI and Ki67, SOX11 expression was not associated with TTF, but patients with low SOX11 expression had shorter OS. On the contrary, high TP53 expression was a strong predictor of TTF and inferior OS compared with low TP53 expression in univariate and multivariate analyses adjusting for MIPI score and Ki-67 index (hazard ratio [HR], 2.0; P = .0054 for TTF, and HR, 2.1; P = .068 for OS). In particular, patients with high TP53 expression (>50% positive lymphoma cells) had a shorter TTF and poor OS independent of both MIPI score and Ki-67 index. Thus, TP53 immunohistochemistry is a suitable test for routine diagnostic practice to assess MCL prognosis.

AimsLow-grade follicular lymphoma (FL) (grade 1/2, FL1/2) has an annual risk of transformation of approximate to 3%, which is associated with aberrations in CDKN2A/B, TP53, and MYC. As in diffuse large B-cell lymphoma, high MYC expression in transformed FL (tFL) might predict a MYC breakpoint.Methods and resultsWe quantified MYC expression by immunohistochemistry and digital analysis in 41 paired biopsies from 20 patients with FL1/2 with subsequent transformation and in four isolated biopsies of tFL. As controls, 28 biopsies of FL1/2 without transformation (median follow-up of 105 months) and nine biopsies of FL3A/B were analysed. In the 20 FL1/2-tFL pairs, MYC expression was significantly higher in tFL than in the initial FL1/2 biopsies (median 54% versus 6%; 7% in FL3A, and 35% in FL3B). MYC breaks (MYC-R) were detected in eight of 21 (38%) tFLs analysed by fluorescence in-situ hybridization (FISH), with a median MYC score of 86%. In two of the analysed tFL cases, the translocation was already detected in antecedent FL1/2. MYC partners were immunoglobulin (IG) loci in three of eight cases (one IGL, one IGH, and one IGK) and non-IG in five of eight cases (two PAX5, one BCL6, and two unknown). Of the eight MYC-R+ cases, six were BCL2+/MYC+ double-hit, one was BCL2+/BCL6+/MYC+ triple-hit, and one was MYC+ single-hit. All three IG-MYC+ cases showed a MYC expression level of >85%, whereas the five cases with a non-IG MYC partner had a wider range of expression (median 68%, range 13-86%). Among the 13 MYC-R- tFLs, two groups with almost dichotomous MYC expression could be observed (three cases showed 90% MYC expression), suggesting alternative mechanisms of MYC activation.Conclusionswe show an increase in MYC expression from FL1/2 to tFL. MYC breakpoints were present in approximate to 40% of the cases, which is markedly higher than in de novo DLBCL. MYC expression was uniformly high in cases with an IG-MYC translocation but much more heterogeneous and in part independent of the presence of a MYC break in non-IG-MYC and MYC-negative cases.

The incidence of diffuse large B-cell lymphoma (DLBCL) increases with age being patient age at diagnosis an adverse prognostic factor. However, elderly patients are often underrepresented in common studies. To investigate the effect between age and biological characteristics in DLBCL, we analyzed data of 1534 patients encompassing all adult age groups, enriched for the age ≥75 years. Follicular lymphoma (FL) grade 3B with histopathological characteristics of DLBCLs were included. Gender, centroblastic cytology, FL grade 3B morphology, CD10 expression, and ABC/non-GCB-subtype were significantly associated with age after correction for multiple testing and after adjusting for cohorts. Analysis of a subgroup points towards an association of MYC expression with age. Our data indicate that biological features of DLBCL and FL grade 3B are associated with increasing age among adult patients. The prevalence of the ABC/non-GCB-subtype in elderly patients suggests that therapies targeting this molecular subtype should be specifically explored in this subgroup.

The t(11;14) translocation that juxtaposes the Cyclin D1 (CCND1) gene to the immunoglobulin heavy chain gene is considered a hallmark of mantel cell lymphoma (MCL).1 Immunohistochemical (IHC) analysis of CCND1 expression in formalin-fixed paraffin-embedded (FFPE) tissue sections of material from patients with suspected MCL is therefore the most obvious and effective diagnostic tool.2 We identified two cases of MCL based on morphology, expression of CD20, CD5 and SOX11 and absence of CD23 expression. Notably, both cases were negative for nuclear CCND1 staining by IHC (Figure 1G,J), despite being positive for the t(11;14)(q13;q32) translocation using fluorescence in situ hybridization (FISH, Figure 1H,L). Patient A was a 81-year-old female presenting with Ann Arbor stage IIIA. After six cycles of R-CHOP (rituximab, clorambucil, vincristine, prednisolone) and two additional cycles of rituximab, she achieved complete remission until last follow up 15 months after initial diagnosis. Patient B was an 87-year-old female with lymphadenopathy on both sides of the diaphragm, but staging remained incomplete. Due to comorbidities and patients' refusal of chemotherapy, rituximab mono-therapy was initiated until last follow up after two months. Surgical excision biopsies of an inguinal (patient A) and cervical (patient B) lymph node were submitted for consultation. In order to investigate if the lack of CCND1 immunostaining was due to low CCND1 expression, we performed quantitative PCR analysis of CCND1 expression in total RNA from patient A and patient B compared to CCND1 expression observed in two classical CCND1-positive MCL cases and two normal lymph nodes. The expression of CCND2 was also investigate as it is known that CCND2 can compensate for CCND1 in some cases.3 As shown in Figure 2A, both patients have CCND1 expression levels similar or higher to that observed in classical MCL samples and much higher than the expression observed in normal lymph nodes. These data are in line with the presence of a t(11;14) translocation in biopsies of the two patients and suggest that the lack of CCND1 immunostaining in patient A and patient B is not due to a defect in mRNA expression.

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.

The differential diagnosis between Burkitt lymphoma (BL) and diffuse large B-cell lymphoma (DLBCL) can be challenging. BL has been reported to express less BCL2 than DLBCL, but this issue has not been analysed systematically. BL expressing BCL2 can be considered to be MYC/BCL2 co-expressors, a feature that is associated with poorer outcome in DLBCL but that has not been correlated with outcome in BL so far. We analysed the expression of BCL2 in 150 cases of conventionally diagnosed BL using two different BCL2 antibodies. BCL2 expression was detected in 23% of the cases, though the expression varied in intensity and number of positive cells. We did not detect any relevant differences in clinical presentation and outcome between BCL2-positive and BCL2-negative BL in a subgroup of 43 cases for which detailed clinical data were available. An independent cohort of 17 BL with expression of BCL2 were analysed molecularly, with 13 of 17 cases classified as molecularly defined BL (Burkitt Lymphoma) using gene expression profiling on formalin-fixed paraffin-embedded tissues. The four lymphomas diagnosed molecularly as intermediates did not differ in clinical presentation and outcome from molecularly defined BL.

The genetic hallmark of Burkitt lymphoma is the translocation t(8;14)(q24;q32), or one of its light chain variants, resulting in IG-MYC juxtaposition. However, these translocations alone are insufficient to drive lymphomagenesis, which requires additional genetic changes for malignant transformation. Recent studies of Burkitt lymphoma using next generation sequencing approaches have identified various recurrently mutated genes including ID3, TCF3, CCND3, and TP53. Here, by using similar approaches, we show that PCBP1 is a recurrently mutated gene in Burkitt lymphoma. By whole-genome sequencing, we identified somatic mutations in PCBP1 in 3/17 (18%) Burkitt lymphomas. We confirmed the recurrence of PCBP1 mutations by Sanger sequencing in an independent validation cohort, finding mutations in 3/28 (11%) Burkitt lymphomas and in 6/16 (38%) Burkitt lymphoma cell lines. PCBP1 is an intron-less gene encoding the 356 amino acid poly(rC) binding protein 1, which contains three K-Homology (KH) domains and two nuclear localization signals. The mutations predominantly (10/12, 83%) affect the KH III domain, either by complete domain loss or amino acid changes. Thus, these changes are predicted to alter the various functions of PCBP1, including nuclear trafficking and pre-mRNA splicing. Remarkably, all six primary Burkitt lymphomas with a PCBP1 mutation expressed MUM1/IRF4, which is otherwise detected in around 20-40% of Burkitt lymphomas. We conclude that PCBP1 mutations are recurrent in Burkitt lymphomas and might contribute, in cooperation with other mutations, to its pathogenesis.

Summary We present the largest series of diffuse large B-cell lymphoma (DLBCL) in patients younger than 18 years analysed to date by gene expression profiling using Nanostring technology to identify molecular subtypes and fluorescent in situ hybridization for translocations of MYC. We show that the activated B cell-like subtype of DLBCL is exceedingly rare in children and – in contrast to adults- not associated with outcome. Furthermore, we review the current literature and demonstrate that MYC translocations are not more frequent in paediatric compared to adult DLBCL. A prognostic role of MYC in the paediatric age groups seems unlikely.

Chromosomal translocations affecting the MYC oncogene are the biological hallmark of Burkitt lymphomas but also occur in a subset of other mature B-cell lymphomas. If accompanied by a chromosomal break targeting the BCL2 and/or BCL6 oncogene these MYC translocation-positive (MYC(+)) lymphomas are called double-hit lymphomas, otherwise the term single-hit lymphomas is applied. In order to characterize the biological features of these MYC(+) lymphomas other than Burkitt lymphoma we explored, after exclusion of molecular Burkitt lymphoma as defined by gene expression profiling, the molecular, pathological and clinical aspects of 80 MYC-translocation-positive lymphomas (31 single-hit, 46 double-hit and 3 MYC(+)-lymphomas with unknown BCL6 status). Comparison of single-hit and double-hit lymphomas revealed no difference in MYC partner (IG/non-IG), genomic complexity, MYC expression or gene expression profile. Double-hit lymphomas more frequently showed a germinal center B-cell-like gene expression profile and had higher IGH and MYC mutation frequencies. Gene expression profiling revealed 130 differentially expressed genes between BCL6(+)/MYC(+) and BCL2(+)/MYC(+) double-hit lymphomas. BCL2(+)/MYC(+) double-hit lymphomas more frequently showed a germinal center B-like gene expression profile. Analysis of all lymphomas according to MYC partner (IG/non-IG) revealed no substantial differences. In this series of lymphomas, in which immunochemotherapy was administered in only a minority of cases, single-hit and double-hit lymphomas had a similar poor outcome in contrast to the outcome of molecular Burkitt lymphoma and lymphomas without the MYC break. Our data suggest that, after excluding molecular Burkitt lymphoma and pediatric cases, MYC(+) lymphomas are biologically quite homogeneous with single-hit and double-hit lymphomas as well as IG-MYC and non-IG-MYC(+) lymphomas sharing various molecular characteristics. peerReviewed

Mantle cell lymphoma (MCL) is a mature B-cell lymphoma characterized by poor clinical outcome. Recent studies revealed the importance of B-cell receptor (BCR) signaling in maintaining MCL survival. However, it remains unclear which role MALT1, an essential component of the CARD11-BCL10-MALT1 complex that links BCR signaling to the NF-κB pathway, plays in the biology of MCL. Here we show that a subset of MCLs is addicted to MALT1, as its inhibition by either RNA or pharmacologic interference induced cytotoxicity both in vitro and in vivo. Gene expression profiling following MALT1 inhibition demonstrated that MALT1 controls an MYC-driven gene expression network predominantly through increasing MYC protein stability. Thus, our analyses identify a previously unappreciated regulatory mechanism of MYC expression. Investigating primary mouse splenocytes, we could demonstrate that MALT1-induced MYC regulation is not restricted to MCL, but represents a common mechanism. MYC itself is pivotal for MCL survival because its downregulation and pharmacologic inhibition induced cytotoxicity in all MCL models. Collectively, these results provide a strong mechanistic rationale to investigate the therapeutic efficacy of targeting the MALT1-MYC axis in MCL patients.

In many B-cell lymphomas, chromosomal translocations are biologic and diagnostic hallmarks of disease. An intriguing subset is formed by the so-called double- hit (DH) lymphomas that are defined by a chromosomal breakpoint affecting the MYC/8q24 locus in combination with another recurrent breakpoint, mainly a t(14;18)(q32;q21) involving BCL2. Recently, these lymphomas have received increased attention, which contributed to the introduction of a novel category of lymphomas in the 2008 WHO classification, “B cell lymphoma unclassifiable with features intermediate between DLBCL and BL.” In this review we explore the existing literature for the most recurrent types of DH B-cell lymphomas and the involved genes with their functions, as well as their pathology and clinical aspects including therapy and prognosis. The incidence of aggressive B-cell lymphomas other than Burkitt lymphoma with a MYC breakpoint and in particular a double hit is difficult to assess, because screening by methods like FISH has not been applied on large, unselected series, and the published cytogenetic data may be biased to specific categories of lymphomas. DH lymphomas have been classified heterogeneously but mostly as DLBCL, the majority having a germinal center phenotype and expression of BCL2. Patients with DH lymphomas often present with poor prognostic parameters, including elevated LDH, bone marrow and CNS involvement, and a high IPI score. All studies on larger series of patients suggest a poor prognosis, also if treated with RCHOP or high-intensity treatment modalities. Importantly, this poor outcome cannot be accounted for by the mere presence of a MYC/8q24 breakpoint. Likely, the combination of MYC and BCL2 expression and/or a related high genomic complexity are more important. Compared to these DH lymphomas, BCL6+/MYC+ DH lymphomas are far less common, and in fact most of these cases represent BCL2+/BCL6+/MYC+ triple-hit lymphomas with involvement of BCL2 as well. CCND1+/MYC+ DH lymphomas with involvement of 11q13 may also be relatively frequent, the great majority being classified as aggressive variants of mantle cell lymphoma. This suggests that activation of MYC might be an important progression pathway in mantle cell lymphoma as well. Based on clinical significance and the fact that no other solid diagnostic tools are available to identify DH lymphomas, it seems advisable to test all diffuse large B-cell and related lymphomas for MYC and other breakpoints.

Typical Burkitt lymphoma is characterized by an IG-MYC translocation and overall low genomic complexity. Clinically, Burkitt lymphoma has a favourable prognosis with very few relapses. However, the few patients experiencing disease progression and/or relapse have a dismal outcome. Here we report cytogenetic findings of seven cases of Burkitt lymphoma in which sequential karyotyping was performed at time of diagnosis and/or disease progression/relapse(s). After case selection, karyotype re-review and additional molecular analyses were performed in six paediatric cases, treated in Berlin-Frankfurt-Munster-Non-Hodgkin lymphoma study group trials, and one additional adult patient. Moreover, we analysed 18 cases of Burkitt lymphoma from the Mitelman database in which sequential karyotyping was performed. Our findings show secondary karyotypes to have a significant increase in load of cytogenetic aberrations with a mean number of 2, 5 and 8 aberrations for primary, secondary and third investigations. Importantly, this increase in karyotype complexity seemed to result from recurrent secondary chromosomal changes involving mainly trisomy 21, gains of 1q and 7q, losses of 6q, 11q, 13q, and 17p. In addition, our findings indicate a linear clonal evolution to be the predominant manner of cytogenetic evolution. Our data may provide a biological framework for the dismal outcome of progressive and relapsing Burkitt lymphoma.

The WHO classification of lymphomas allows for a group of diseases that have features intermediate between those of Burkitt lymphoma and diffuse large B-cell lymphoma. These are a diverse group of diseases whose genetics and clinical course are yet to be fully described. We report an unusual case of high grade B-cell lymphoma, intermediate between DLBCL and BL, lacking CD10 expression in which the chromosomal translocation t(3;8)(q27;q24) was found to be the sole chromosomal abnormality. FISH analysis demonstrated juxtaposition of theBCL6andMYCloci without obvious involvement of theIGHlocus, suggesting constitutiveMYCexpression due to promoter substitution. The patient responded to intensive chemotherapy and remains in remission two years after finishing therapy.