A Lucky Mistake: The Splenic Glands of Marcello Malpighi

PURPOSE OF THE REVIEW: More than 50% of all gynaecological cancers can be classified as rare tumours (defined as an annual incidence of <6 per 100,000) and such tumours represent an important challenge for clinicians. RECENT FINDINGS: Rare cancers account for more than one fifth of all new cancer diagnoses, more than any of the single common cancers alone. Reviewing the RARECAREnet database, some of the tumours occur infrequently, whilst others because of their natural history have a high prevalence, and therefore appear to be more common, although their incidence is also rare. Harmonization of medical practice, guidelines and novel trials are needed to identify rare tumours and facilitate the development of new treatments. Ovarian tumours are the focus of this review, but we comment on other rare gynaecological tumours, as the diagnosis and treatment challenges faced are similar. FUTURE: This requires European collaboration, international partnerships, harmonization of treatment and collaboration to overcome the regulatory barriers to conduct international trials. Whilst randomized trials can be done in many tumour types, there are some for which conducting even single arm studies may be challenging. For these tumours alternative study designs, robust collection of data through national registries and audits could lead to improvements in the treatment of rare tumours. In addition, concentring the care of patients with rare tumours into a limited number of centres will help to build expertise, facilitate trials and improve outcomes

The effects of hematopoietic stem cell transplant on splenic extramedullary hematopoiesis in patients with myeloproliferative neoplasm-associated myelofibrosis

Background/objective: Hematopoietic stem cell transplant (HSCT) is the only curative treatment for myeloproliferative neoplasm-associated myelofibrosis (MPN-MF). The main clinical manifestation of MPN-MF is splenomegaly secondary to extramedullary hematopoiesis (EMH). The effects of HSCT on splenic EMH and associated vascular and stromal changes are unknown. This study compares the findings seen in spleens following HSCT with those of nontransplanted patients, normal controls, and matched bone marrow (BM) samples. Methods: This study included three transplanted MPN-MF spleens, three nontransplanted MPN-MF spleens, and three normal controls. Spleens were assessed for: (a) presence/extent of EMH; (b) presence of Gamna–Gandy bodies; (c) splenic fibrosis; (d) CD34-positive microvessel density; (e) CD8-positive sinusoids; (f) frequency of smooth muscle actin-positive myoid cells; and (g) nerve growth factor receptor-positive adventitial reticulum cells. In two cases, matched BM samples were assessed for cellularity, presence of atypical megakaryocytes, and fibrosis. Results: Compared with normal controls, all MPN-MF spleens were larger in size, had EMH, red pulp fibrosis, higher CD34-positive microvessel density, and decreased CD8-positive sinusoids. Compared with nontransplanted cases, post-HSCT spleens showed disappearance or reduction of EMH. Gamna–Gandy bodies were increased; no differences in the remaining parameters were found. A reduction of splenic EMH was associated with normalization of BM cellularity and megakaryopoiesis. Conclusion: HSCT reduces/abrogates splenic EMH and is associated with an increased number of Gamna–Gandy bodies, which may suggest vascular damage. The lack of stromal changes in spleens removed shortly after transplant is in line with similar observations in the BM, where a longer interval is often necessary for resolution of fibrosis. Keywords: Hematopoietic stem cell transplant, Myelofibrosis, Myeloproliferative neoplasms, Splee

Clinical Significance of PTEN Deletion, Mutation, and Loss of PTEN Expression in De Novo Diffuse Large B-Cell Lymphoma

PTEN loss has been associated with poorer prognosis in many solid tumors. However, such investigation in lymphomas is limited. In this study, PTEN cytoplasmic and nuclear expression, PTEN gene deletion, and PTEN mutations were evaluated in two independent cohorts of diffuse large B-cell lymphoma (DLBCL). Cytoplasmic PTEN expression was found in approximately 67% of total 747 DLBCL cases, more frequently in the activated B-cell-like subtype. Nuclear PTEN expression was less frequent and at lower levels, which significantly correlated with higher PTEN mRNA expression. Remarkably, loss of PTEN protein expression was associated with poorer survival only in DLBCL with AKT hyperactivation. In contrast, high PTEN expression was associated with Myc expression and poorer survival in cases without abnormal AKT activation. Genetic and epigenetic mechanisms for loss of PTEN expression were investigated. PTEN deletions (mostly heterozygous) were detected in 11.3% of DLBCL, and showed opposite prognostic effects in patients with AKT hyperactivation and in MYC rearranged DLBCL patients. PTEN mutations, detected in 10.6% of patients, were associated with upregulation of genes involved in central nervous system function, metabolism, and AKT/mTOR signaling regulation. Loss of PTEN cytoplasmic expression was also associated with TP53 mutations, higher PTEN-targeting microRNA expression, and lower PD-L1 expression. Remarkably, low PTEN mRNA expression was associated with down-regulation of a group of genes involved in immune responses and B-cell development/differentiation, and poorer survival in DLBCL independent of AKT activation. Collectively, multi-levels of PTEN abnormalities and dysregulation may play important roles in PTEN expression and loss, and that loss of PTEN tumor-suppressor function contributes to the poor survival of DLBCL patients with AKT hyperactivation

<html>Prognostic impact of concurrent <i>MYC</i> and <i>BCL6</i> rearrangements and expression in <i>de novo</i> diffuse large B-cell lymphoma</html>

Double-hit B-cell lymphoma is a common designation for a group of tumors characterized by concurrent translocations of MYC and BCL2, BCL6, or other genes. The prognosis of concurrent MYC and BCL6 translocations is not well known. In this study, we assessed rearrangements and expression of MYC, BCL2 and BCL6 in 898 patients with de novo diffuse large B-cell lymphoma treated with standard chemotherapy (cyclophosphamide, doxorubicin, vincristine, and prednisone plus rituximab). Neither BCL6 translocation alone (more frequent in activated B-cell like diffuse large B-cell lymphoma) nor in combination with MYC translocation (observed in 2.0% of diffuse large B-cell lymphoma) predicted poorer survival in diffuse large B-cell lymphoma patients. Diffuse large B-cell lymphoma patients with MYC/BCL6 co-expression did have significantly poorer survival, however, MYC/BCL6 co-expression had no effect on prognosis in the absence of MYC/BCL2 co-expression, and had no additive impact in MYC+/BCL2+ cases. The isolated MYC+/BCL6+/BCL2− subset, more frequent in germinal center B-cell like diffuse large B-cell lymphoma, had significantly better survival compared with the isolated MYC+/BCL2+/BCL6− subset (more frequent in activated B-cell like diffuse large B-cell lymphoma). In summary, diffuse large B-cell lymphoma patients with either MYC/BCL6 rearrangements or MYC/BCL6 co-expression did not always have poorer prognosis; MYC expression levels should be evaluated simultaneously; and double-hit B-cell lymphoma needs to be refined based on the specific genetic abnormalities present in these tumors

p63 expression confers significantly better survival outcomes in high-risk diffuse large B-cell lymphoma and demonstrates p53-like and p53-independent tumor suppressor function

The role of p53 family member, p63 in oncogenesis is the subject of controversy. Limited research has been done on the clinical implications of p63 expression in diffuse large B-cell lymphoma (DLBCL). In this study, we assessed p63 expression in de novo DLBCL samples (n=795) by immunohistochemistry with a pan-p63-monoclonal antibody and correlated it with other clinicopathologic factors and clinical outcomes. p63 expression was observed in 42.5% of DLBCL, did not correlate with p53 levels, but correlated with p21, MDM2, p16INK4A, Ki-67, Bcl-6, IRF4/MUM-1 and CD30 expression, REL gains, and BCL6 translocation. p63 was an independent favorable prognostic factor in DLBCL, which was most significant in patients with International Prognostic Index (IPI) >2, and in activated-B-cell–like DLBCL patients with wide-type TP53. The prognostic impact in germinal-center-B-cell–like DLBCL was not apparent, which was likely due to the association of p63 expression with high-risk IPI, and potential presence of ∆Np63 isoform in TP63 rearranged patients (a mere speculation). Gene expression profiling suggested that p63 has both overlapping and distinct functions compared with p53, and that p63 and mutated p53 antagonize each other. In summary, p63 has p53-like and p53-independent functions and favorable prognostic impact, however this protective effect can be abolished by TP53 mutations

Erratum: Clinical and biological significance of de novo CD5+ diffuse large B-cell lymphoma in Western countries

CD5 is a pan-T-cell surface marker and is rarely expressed in diffuse large B-cell lymphoma (DLBCL). Large-scale studies of de novo CD5+ DLBCL are lacking in Western countries. In this study by the DLBCL Rituximab-CHOP Consortium, CD5 was expressed in 5.5% of 879 DLBCL patients from Western countries. CD5+ DLBCL was associated with higher frequencies of >1 ECOG performance status, bone marrow involvement, central nervous system relapse, activated B-cell–like subtype, Bcl-2 overexpression, and STAT3 and NF-κB activation, whereas rarely expressed single-stranded DNA-binding protein 2 (SSBP2), CD30 or had MYC mutations. With standard R-CHOP chemotherapy, CD5+ DLBCL patients had significantly worse overall survival (median, 25.3 months vs. not reached, P< .0001) and progression-free survival (median, 21.3 vs. 85.8 months, P< .0001) than CD5− DLBCL patients, which was independent of Bcl-2, STAT3, NF-κB and the International Prognostic Index. Interestingly, SSBP2 expression abolished the prognostic significance of CD5 expression, suggesting a tumor-suppressor role of SSBP2 for CD5 signaling. Gene-expression profiling demonstrated that B-cell receptor signaling dysfunction and microenvironment alterations are the important mechanisms underlying the clinical impact of CD5 expression. This study shows the distinctive clinical and biological features of CD5+ DLBCL patients in Western countries and underscores important pathways with therapeutic implications

Prognostic impact of c-Rel nuclear expression and REL amplification and crosstalk between c-Rel and the p53 pathway in diffuse large B-cell lymphoma

Dysregulated NF-κB signaling is critical for lymphomagenesis. The regulation, function, and clinical relevance of c-Rel/NF-κB activation in diffuse large B-cell lymphoma (DLBCL) have not been well studied. In this study we analyzed the prognostic significance and gene-expression signature of c-Rel nuclear expression as surrogate of c-Rel activation in 460 patients with de novo DLBCL. Nuclear c-Rel expression, observed in 137 (26.3%) DLBCL patients frequently associated with extranoal origin, did not show significantly prognostic impact in the overall- or germinal center B-like-DLBCL cohort, likely due to decreased pAKT and Myc levels, up-regulation of FOXP3, FOXO3, MEG3 and other tumor suppressors coincided with c-Rel nuclear expression, as well as the complicated relationships between NF-κB members and their overlapping function. However, c-Rel nuclear expression correlated with significantly poorer survival in p63+ and BCL-2− activated B-cell-like-DLBCL, and in DLBCL patients with TP53 mutations. Multivariate analysis indicated that after adjusting clinical parameters, c-Rel positivity was a significantly adverse prognostic factor in DLBCL patients with wild type TP53. Gene expression profiling suggested dysregulations of cell cycle, metabolism, adhesion, and migration associated with c-Rel activation. In contrast, REL amplification did not correlate with c-Rel nuclear expression and patient survival, likely due to co-amplification of genes that negatively regulate NF-κB activation. These insights into the expression, prognostic impact, regulation and function of c-Rel as well as its crosstalk with the p53 pathway underscore the importance of c-Rel and have significant therapeutic implications

Age cutoff for Epstein-Barr virus-positive diffuse large B-cell lymphoma&#x2013;is it necessary

Epstein-Barr virus-positive diffuse large B-cell lymphoma of the elderly (EBV+ DLBCL-e) is a molecularly distinct variant of DLBCL, characterized by a monoclonal B-cell proliferation that occurs in patients >50 years of age without a history or clinicopathologic evidence of immunodeficiency. However, patients with EBV+ DLBCL younger than 50-years-old also exist in Western countries. We evaluated the clinicopathologic, immunophenotypic and genetic features in Cacausian patients with EBV+ DLBCL who are ≤50 years of age and compared this patient group to patients who are >50 years. In patients who are ≤50 years, less frequent expression of BCL6 and a trend of more frequent expression of CD30 and pSTAT3 were found in patients with EBV+ DLBCL. In patients who are >50 years, common expression of CD30, p50, pSTAT3 and less frequent expression of BCL6 were observed. Older patients also more commonly had a poor performance status (ECOG≥2). Comparing EBV+ DLBCL patients in ≤50 years versus >50 years, both groups had similar clinicopathologic, immunophenotypic and genetic features. Gene expression profiling, microRNA profiling and treatment outcome of the younger patients with EBV+ DLBCL was not distinctive from tumors in older patients. Based on our data, we suggest that the arbitrary age cutoff for EBV+ DLBCL is unnecessary and should be eliminated in the WHO lymphoma classification scheme

2009

ABSTRACT © F e r r a t a S t o r t i F o u n d a t i o n BCL2 translocations are more frequently found in the GCB subtype, whereas 18q21 locus amplification is more common in the ABC subtype of DLBCL. 3, Design and Methods Patients We studied 327 cases of previously untreated de novo DLBCL, diagnosed between January 2002 and October 2009, and collected as part of the International DLBCL Rituxan-CHOP Consortium Program Study. These cases were analyzed for Bcl-2 protein expression, and BCL2 and MYC gene abnormalities, and gene expression profiling (GEP) was performed. All cases were reviewed by a group of hematopathologists (SMM, MAP, MBM, AT, and KHY), and the diagnoses were confirmed based on World Health Organization classification criteria. Patients with transformation from low grade lymphoma, those with composite follicular lymphoma, primary mediastinal large B-cell lymphoma, primary cutaneous and primary central nervous system DLBCL were excluded from the analysis due to the unique biological features of these types of lymphoma. All patients were adults who were negative for human immunodeficiency virus and had sufficient clinical data and clinical follow-up. Patients in this study were treated with R-CHOP (n=291, 89%) or R-CHOP-like regimens (n=36, 11%; CHOP scheme adopting different anthracyclines i.e. novantrone or epirubicin). All patients with advanced stage disease received six (92%) or eight (8%) cycles, every 21 days, with or without radiotherapy for residual disease or initial bulky disease; localized cases received at least three cycles followed by radiotherapy or six cycles without radiotherapy. The current study was approved by each of the participating centers&apos; Institutional Review Boards, and the overall collaborative study was approved by the Institutional Review Board at The University of Texas MD Anderson Cancer Center in Houston, Texas, USA. Immunohistochemistry for Bcl-2 and cut-off determination Bcl-2 protein expression was evaluated in all patients using a monoclonal anti-Bcl-2 antibody (Clone-124, Dako, Carpinteria, CA, USA) and standard immunohistochemical methods. The formalin-fixed, paraffin-embedded tissue slides underwent deparaffinization and heat-induced antigen retrieval techniques. An endogenous biotin-blocking kit (Ventana) was used to decrease background staining. Following antigen retrieval and primary antibody incubation, the reaction was completed in a Ventana ES instrument using a diaminobenzidine immunoperoxidase detection kit (Ventana). Immunoreactivity was determined without knowledge of the patients&apos; survival, clinical data, or GEP data. The samples were analyzed independently by a group of four hematopathologists/pathologists in addition to the hematopathologist of each of the contributing centers, and disagreements were resolved by joint review at a multi-headed microscope. An average of 300-400 cells in four to five fields were counted in the tissue microarray cores. A percentage of tumor cell staining ≥50% was considered positive after receiver operating characteristic (ROC) curve analysis was implemented to assess the discriminatory accuracy of Bcl-2 protein in recognizing patients with different overall survival (OS) and progression-free survival (PFS). The 50% value was established from the analysis of the area under the ROC curve (AUROC) and had the maximum specificity and sensibility for OS and PFS discrimination in our patients (AUROC=0.564, P=0.017 for OS and AUROC=0.564, P=0.015 for PFS). 31 Gene expression profiling analysis RNA was extracted from 327 formalin-fixed, paraffin-embedded tissue samples using a HighPure Paraffin RNA Extraction Kit (Roche Applied Science). Fifty nanograms of RNA were transcribed into cDNA, linearly amplified using the WT-Ovation™ FFPE System (Nugen), and biotin-labeled using FL-Ovation™ cDNA Biotin Module V2 (Nugen) in all cases. For GeneChip hybridization, 5 μg of WT-Ovation amplified cDNA were applied to HG-U133 Plus 2.0 GeneChips (Affymetrix) and hybridized overnight. GeneChips were washed, stained, and scanned using the Fluidic Station 450 and GeneChip Scanner 3000 (Affymetrix) according to the manufacturer&apos;s recommendations. For data analysis and classification, the microarray DQN (trimmed mean of differences of perfect match and mismatch intensities with quantile normalization) signals were generated and normalized to the quantiles of beta distribution with parameters p=1.2 and q=3 as previously described. 32 A Bayesian model was also utilized to determine the class probability. The classification model was built on the 47 paired formalin-fixed, paraffin-embedded tissue sample dataset previously generated with a confidence rate of 90-100% in fresh frozen tissue and 92-100% in formalin-fixed, paraffinembedded tissue. The same methodology developed during this study has been validated and demonstrated to be applicable by using the LLMPP dataset in the Gene Expression Omnibus (GEO) database GSE#10846 that has 181 CHOP-treated and 233 R-CHOP-treated DLBCL patients with fresh-frozen samples. 3, Validation set To validate our observations in predicting survival in an independent series of cases, we analyzed a second group of 120 archival DLBCL cases studied similarly to the first cohort except for MYC analysis that was not available (GCB 49%, ABC 40%, unclassified 11%; BCL2 translocations in 18%; Bcl-2 overexpression in 54%). All these patients had been treated with R-CHOP and the same selection criteria as those for the first cohort were applied. The clinical characteristics at presentation of the patients in the validation set were not significantly different from those of the patients in the test set. Statistical analysis Following pre-defined criteria, 33 PFS was measured from the time of diagnosis to the time of progression or death from any cause. OS was measured from the time of diagnosis to last followup or death from any cause. Only patients with a follow-up of longer than 12 months were included in the survival analysis. The actuarial probabilities of PFS and OS were determined using the Kaplan-Meier method, and differences were compared using the log-rank test. A Cox proportional-hazards model was used for multivariate analysis. The χ 2 test or Mann-Whitney test was applied to assess differences between variables. The interobserver agreement for FISH was assessed using the κ statistic; a κ value of &gt;0.75 implied excellent agreement. All statistical calculations, except for ROC and the κ statistic which were performed with SPSS 18.0 (SPSS Inc., Chicago, IL, USA), were conducted using StatView (Abacus Concepts, Berkeley, CA, USA). Results Patients&apos; characteristics and outcome The median age of the patients at diagnosis was 62 years (range, 18-86). Their clinical characteristics are reported in BCL2 and MYC genes in the subgroups defined by gene expression profiling Sixty patients (18.3%) had DLBCL with BCL2 gene translocations, and 50 (15.3%) had BCL2 gene amplifications. The presence of BCL2 translocations was not associated with any clinical prognostic variable at diagnosis, except for Ann Arbor Stage (70% versus 49% with stage III-IV, P=0.004), as shown in The OS and PFS rates of patients with BCL2 translocations were similar to those of patients without BCL2 translocations, irrespectively of MYC status. When we restricted the analysis to the GCB subtype, patients with BCL2 translocations alone, in the absence of MYC breaks, had a significantly worse outcome than GCB patients without BCL2 translocations (3-year PFS of 53% versus 76%, respectively; P=0.0002). The outcome of patients with BCL2 rearranged GCB subtype was similar to that of the patients with the ABC subtype of DLBCL (52%, P=0.30), but still better than that of the patients with double hit lymphomas (P&lt;0.0001, The presence of MYC breaks alone in the 19 patients without concomitant BCL2 translocations was not associated with impaired PFS (P=0.70) or OS (P=0.66) in the whole cohort, but was associated with inferior OS (P=0.03), but not PFS (P=0.22), in patients with GCB-DLBCL (only 9 with isolated MYC breaks). As shown in BCL2 gains were not prognostic in any of the subgroups of patients. Particular consideration of high-level amplifications was of no additional prognostic value. Bcl-2 protein expression, clinical characteristics, fluorescence in situ hybridization and gene expression profiling None of the common clinical characteristics of our patients at the time of presentation was significantly associated with Bcl-2 protein expression except age, with older patients more often being Bcl-2 positive (≥60 years old, P=0.02). Bcl-2 protein expression in GEP-and FISHdefined subgroups is shown in © F e r r a t a S t o r t i F o u n d a t i o n patients without the BCL2 translocation (range, 0-100%; median 60%). Bcl-2 protein expression was significantly associated with worse PFS (P=0.01) and OS (P=0.02) in the whole cohort, but when patients were divided according to GEPdefined subtypes, we observed that higher Bcl-2 expression was associated with significantly inferior PFS in the GCB subgroup (P=0.04), but not in the ABC subgroup (P=0.57), as shown in Multivariate analysis Multivariate analysis of all 137 patients with the GCB subtype of DLBCL showed that BCL2 translocations (HR 0.40, 95% CI: 0.18-0.89; P=0.02), but not Bcl-2 expression (HR 1.01, 95% CI: 0.45-2.21; P=0.98), MYC breaks (HR 0.25, 95% CI: 0.10-0.59; P=0.001), and IPI score (HR 0.41, 95% CI: 0.20-0.84; P=0.01), were independently associated with patients&apos; outcome. Results were not modified after each molecular feature was computed with age as a continuous parameter. C. Visco et al. 258 haematologica | 2013; 98(2) Overall survival Progression-free survival Four-hundred and forty-four genes were found to be differentially expressed (&gt;1.5 fold and P&lt;0.005) in DLBCL patients with or without BCL2 translocations including both GCB and ABC subtypes. In the GCB group, however, only 43 genes were differentially expressed among patients with and without BCL2 translocations ( Interestingly, a number of genes overexpressed in the BCL2 translocated group are involved in the control of angiogenesis and the inflammatory response (AIMP1, PPIA, and ALOX), while others are involved in promoting apoptosis or regulating B-cell signaling (STK17A, RAL-GPS2, NCOA3, STRBP, and ZNF117). 35-37 C. Visco et al. 260 haematologica | 2013; 98(2) © F e r r a t a S t o r t i F o u n d a t i o n Discussion We addressed the clinical impact of BCL2 aberrations and their relationship to Bcl-2 protein expression in a large series of patients with DLBCL homogeneously treated with R-CHOP, with known MYC gene status and molecularly characterized according to GEP analysis. We were able to establish the role of the BCL2 gene in different subtypes of DLBCL, irrespectively of concomitant MYC aberrations. We found that isolated BCL2 translocations, in the absence of MYC breaks, were associated with a poor outcome in the subset of patients with GCB-DLBCL, and that the prognosis of these patients was similar to that of patients with ABC-DLBCL. The concomitant presence of MYC breaks (double hit lymphoma) further worsened the outcome of these patients. The role of Bcl-2 protein expression appeared dependent on its association with BCL2 translocations, as outlined by multivariate analysis and survival curves As determined by FISH break apart probe analysis, the overall frequency of BCL2 translocations in de novo DLBCL was 18.3%. The BCL2 translocations were almost exclusively associated with GCB-DLBCL, found in 34.5% of cases The impact of BCL2 translocations on survival in our series could not be explained by differences in the clinical features of the patients because there was no association between the presence of BCL2 translocations and IPI risk groups (P=0.90, A C B FIGURE A COLORI SOLO ONLINE © F e r r a t a S t o r t i F o u n d a t i o n with isolated BCL2 or MYC lesions. Confirming previous findings, In this series, Bcl-2 protein was overexpressed in half of the patients with GCB-DLBCL and in 72% of patients with ABC-DLBCL 18,39 However, Bcl-2 overexpression had prognostic value only in the GCB subtype, as already observed by others in the era of R-CHOP therapy. Iqbal et al. 22 Secondly, Bcl-2 protein expression in Iqbal&apos;s study was significantly associated with adverse clinical prognostic factors (stage III-IV, elevated lactate dehydrogenase, high IPI risk group) in GCB-DLBCL, which was not the case in our study. Finally, no mention was made about exclusion of possibly confounding DLBCL subtypes such as double hit lymphoma, primary cutaneous or primary central nervous system DLBCL. We also acknowledge that different findings in the literature regarding BCL2 rearrangements or protein expression could very well be related to lack of uniformity between different studies in terms of Bcl-2 staining and scoring. Moreover, patients&apos; characteristics in the different series, differences in the management of the cases as they were not in clinical trials, data collection regarding outcome, and sometimes short follow-up times may also have contributed to different results. Our GEP analysis revealed that patients with BCL2 translocations substantially differed with respect to important recurrent oncogenic events, which may contribute to the adverse outcome of the subgroup of GCB-DLBCL patients with BCL2 translocations. Up-regulation of the BCL11A gene occurred exclusively in the group of patients with BCL2 translocations We confirm that the outcome of GCB-DLBCL patients should be interpreted in the context of abnormalities of the MYC and BCL2 genes. While the MYC rearrangement is quite rare, it is rarely found as the sole genetic abnormality, and its clinical relevance is mainly related to a double hit mechanism, BCL2 rearrangements are present in a considerable fraction of patients with the GCB subtype who have similar outcomes to those of patients with the ABC subtype. Our results confirm that the GCB and ABC subtypes of DLBCL have distinct pathogeneses, and support the rationale for further classification of different subgroups. © F e r r a t a S t o r t i F o u n d a t i o n Funding CV is a hematologist supported by Sa