Clinicopathological features of double‐hit B‐cell lymphomas with MYC and BCL2, BCL6 or CCND1 rearrangements

Double‐hit (DH) lymphomas are B‐cell lymphomas characterized by chromosomal rearrangements, specifically of MYC and either BCL2, BCL6 or CCND1. We reviewed 22 cases of DH lymphomas. BCL2/MYC DH lymphomas constituted the majority of these DH lymphomas (17 cases; 77%), followed by BCL6/MYC (2 cases; 9%) lymphomas. Assessing morphological features using the 2008 World Health Organization classification system, 15 cases (68%) were determined to be B‐cell lymphoma, unclassifiable with features intermediate between diffuse large B‐cell lymphoma (DLBCL) and Burkitt lymphoma (BCLU) (10 cases; 45%), or as DLBCL (5 cases; 23%), and 2 cases (9%) were classified as morphologically untransformed follicular lymphoma. Burkitt lymphoma was rare (1 case; 5%) among DH lymphomas. Nineteen cases were treated with R‐CHOP or a high dose chemotherapy regimen. After a median follow‐up of 11 months, 7 patients had died, and the 1‐year survival rate was 62.5%. High dose chemotherapy did not improve the outcome. We suggest that screening of genetic variations to detect DH lymphomas is required in diagnosing all lymphomas, even those determined morphologically to be follicular lymphoma.     

The expression of Bcl‐2 by proliferating cells varies in different categories of B‐cell lymphoma

Masir N, Jones M, Lee A M, Goff L K, Clear A J, Lister A, Marafioti T & Mason D Y
(2010) Histopathology 56 , 617–626 The expression of Bcl‐2 by proliferating cells varies in different categories of B‐cell lymphoma Aims: To investigate the relationship between Bcl‐2 protein expression and cell proliferation at single‐cell level in B‐cell lymphomas using double‐labelling techniques. Methods and results: The relationship between Bcl‐2 protein expression and cell proliferation was explored in 124 cases of B‐cell lymphoma using double immunofluorescence labelling for Bcl‐2 and Ki67. In follicular lymphoma, marginal zone lymphoma and a subset of chronic lymphocytic leukaemia/small lymphocytic lymphoma (CLL/SLL), neoplastic cells tended to lose Bcl‐2 when they are in cell cycle. This pattern is usually maintained in both follicular lymphoma and CLL/SLL when they undergo high‐grade transformation. In mantle cell lymphoma, diffuse large B‐cell lymphoma and a subset of CLL/SLL, the inverse relationship (between Bcl‐2 and Ki67) was not observed, i.e. the proliferating cells tended to show co‐expression of Bcl‐2. Conclusions: In low‐grade lymphomas, including those that are transformed, Bcl‐2 expression is lost when cell proliferate. However, in more aggressive tumours (i.e. mantle cell and de novo diffuse large B‐cell lymphomas) the inverse Bcl‐2/Ki67 relationship was not observed. It would be of interest to explore the clinical implications in lymphoma of the presence and absence of the inverse Bcl‐2/Ki67 pattern.     

Differential expression of Toll-like receptors in follicular lymphoma,diffuse large B-cell lymphoma and peripheral T-cell lymphoma

Although Toll-like receptors (TLRs) in mammals are well-known to play important roles in innate immunity, newer roles for the TLRs have suggested that cells with aberrant TLR expression may have a survival advantage over normal cells. Lymphocytes are one of a small number of cell types that express many of the TLRs, suggesting that abnormal TLR levels/signaling may potentially influence the progression of malignant lymphomas. Thus, frozen samples of 51 lymph nodes from patients with follicular lymphoma (FL), diffuse large B-cell lymphoma (DLBCL) and peripheral T-cell lymphoma (PTCL) were analyzed for the expression of TLR1 to 9 using quantitative real-time PCR, and compared to those in reactive lymphadenopathy (RL) samples. TLR2 was over-expressed in both DLBCL and PTCL but not in FL when compared to RL. TLR1 and TLR4 expression was up-regulated in PTCL, while TLR8 was highly expressed in DLBCL. Although TLR5 showed lower expression in FL, expression of TLR3, TLR6, TLR7 and TLR9 did not vary significantly between different lymphoma subtypes. Double immunostaining revealed an increase in the number of TLR2 and/or TLR8 expressing lymphoma cells in DLBCL. In PTCL, TLR2 and TLR4 expression was localized to neoplastic T cells. TLR expression is highly variable among lymphoma subtypes. However, despite this some significant differences exist that may prove useful in the development of novel therapeutic strategies.     

IgM expression in paraffin sections distinguishes follicular lymphoma from reactive follicular hyperplasia

The trapping of IgM-containing immune complexes (ICs) by follicular dendritic cells (FDCs) serves as an important step in promoting germinal center (GC) formation. Thus, the deposition of IgM-containing ICs on FDCs can be detected by antibodies recognizing IgM. The present investigation provides the first comprehensive report on the IgM staining pattern in follicular lymphoma (FL, n = 60), with comparisons to reactive follicular hyperplasias (RFH, n = 25), demonstrating that immunohistochemical staining for IgM in paraffin-embedded sections seems to be an additional tool for differentiating between FL and RFH. In RFH, IgM highlighted processes of FDCs, with stronger and more compact staining in light than in dark zones, with occasional very dim staining of GC B cells. In FL, IgM expression patterns were of three types. Pattern I (38 cases) stained tumor cells within neoplastic follicles, with no staining of FDCs. Pattern II (15 cases) stained neither tumor cells nor FDCs. Pattern III (7 cases) stained tumor cells with (3 cases) or without (4 cases) IgM expression; however, variable and attenuated IgM expression was observed on FDCs in each case. Interestingly, significant numbers of IgD+ mantle cells were preserved around the neoplastic follicles in these 7 cases. The data suggested that a complete or considerable loss of IgM expression in FDCs, reflecting the loss of IgM-containing ICs in FDCs, is a typical feature of FL. Increased IgM expression by GC B cells can also serve as an indicator of immunophenotypic abnormality in FL.     

Characterization of ectopic lymphoid structures in different types of acute renal allograft rejection

We hypothesize that T cells such as interleukin (IL)‐21⁺B cell lymphoma 6 (BCL6)⁺ T follicular helper cells can regulate B cell‐mediated immunity within the allograft during acute T cell‐mediated rejection; this process may feed chronic allograft rejection in the long term. To investigate this mechanism, we determined the presence and activation status of organized T and B cells in so‐called ectopic lymphoid structures (ELSs) in different types of acute renal allograft rejection. Biopsies showing the following primary diagnosis were included: acute/active antibody‐mediated rejection, C4d⁺ (a/aABMR), acute T cell‐mediated rejection grade I (aTCMRI) and acute T cell‐mediated rejection grade II (aTCMRII). Paraffin sections were stained for T cells (CD3 and CD4), B cells (CD20), follicular dendritic cells (FDCs, CD23), activated B cells (CD79A), immunoglobulin (Ig)D, cell proliferation (Ki67) and double immunofluorescent stainings for IL‐21 and BCL6 were performed. Infiltrates of T cells were detected in all biopsies. In aTCMRI, B cells formed aggregates surrounded by T cells. In these aggregates, FDCs, IgD and Ki67 were detected, suggesting the presence of ELSs. In contrast, a/aABMR and aTCMRII showed diffuse infiltrates of T and B cells but no FDCs and IgD. IL‐21 was present in all biopsies. However, co‐localization with BCL6 was observed mainly in aTCMRI biopsies. In conclusion, ELSs with an activated phenotype are found predominantly in aTCMRI where T cells co‐localize with B cells. These findings suggest a direct pathway of B cell alloactivation at the graft site during T cell mediated rejection.     

A case of diffuse large B‐cell lymphoma transformed from primary duodenal follicular lymphoma

Primary intestinal follicular lymphoma (FL) is a variant of FL characterized by frequent duodenal involvement and a very indolent clinical behavior without therapy. Unlike nodal FL, there have been no reports of histologic transformation (HT) or death attributable to primary intestinal FL. Here, we report the first case of primary duodenal FL showing HT. A Grade 1 FL in the duodenum was incidentally detected in a 73‐year‐old man. A watch‐and‐wait strategy was adopted because the disease was stage IE. Six months later, bone marrow involvement was suspected. The intestinal lesions had not changed during the first year since the initial diagnosis. Sixty‐two months after the initial diagnosis, a biopsy specimen showed diffuse large B‐cell lymphoma (DLBCL). A perforation of the intestine occurred before chemotherapy was started. Partial resection was performed and subsequent chemotherapy was administered. The clone of the initial FL and DLBCL were identical according to PCR analysis, indicating that the primary intestinal FL had transformed into DLBCL. Although HT is rare, it could occur in some patients with primary intestinal FL. Based on this case, it may be necessary to re‐evaluate the clinical watch‐and‐wait strategy for primary intestinal FL in some patients.     

Nodular lymphocyte predominant Hodgkin lymphoma and diffuse large B-cell lymphoma: a study of six cases concurrently involving the same site

Cotta C V, Coleman J F, Li S & Hsi E D
(2011) Histopathology  59 , 1194–1203
Nodular lymphocyte predominant Hodgkin lymphoma and diffuse large B‐cell lymphoma: a study of six cases concurrently involving the same site Aims: Nodular lymphocyte‐predominant Hodgkin lymphoma (NLPHL) is a slowly progressing neoplasm with a favourable prognosis. However, in a minority of cases (3–12%) it progresses to a clonally related diffuse large B‐cell lymphoma (DLBCL), diagnosed between 6 months and 24 years after NLPHL. This study investigated six cases of NLPHL and DLBCL at the same location. Methods and results: The patients were five men and one woman. In four cases, the site was an axillary lymph node, and in two it was inguinal. In all cases, NLPHL areas had typical morphological and immunophenotypic features. DLBCL involvement was multifocal, diffuse, and characterized by large centroblastic and anaplastic cells. Immunohistochemical studies showed DLBCL cells to be positive for CD20, CD45, and BCL6. In one case, DLBCL cells were positive for BCL2, and in two cases they were positive for MUM‐1. There were no networks of follicular dendritic cells (FDC) associated with DLBCL. Rosettes of PD‐1‐positive and CD57‐positive cells surrounding malignant cells in NLPHL were absent in DLBCL. All the cases were negative for Epstein–Barr virus. No translocations involving MYC were identified in DLBCL. Treatment and outcome were known in four cases. All of these patients were treated with rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R‐CHOP), and this was followed by clinical remission (CR). Conclusions: In adequately sampled tumors, DLBCL can be associated with NLPHL at diagnosis. Diffuse architecture, loss of FDC networks, sometimes immunophenotype shift are characteristics of DLBCL associated with NLPHL. Treatment with R‐CHOP usually leads to CR.     

Amplification of 2p as a genomic marker for transformation in lymphoma

To outline further genetic mechanisms of transformation from follicular lymphoma (FL) to diffuse large B‐cell lymphoma (DLBCL), we have performed whole genome array‐CGH in 81 tumors from 60 patients [29 de novo DLBCL (dnDLBCL), 31 transformed DLBCL (tDLBCL), and 21 antecedent FL]. In 15 patients, paired tumor samples (primary FL and a subsequent tDLBCL) were available, among which three possessed more than two subsequent tumors, allowing us to follow specific genetic alterations acquired before, during, and after the transformation. Gain of 2p15–16.1 encompassing, among others, the REL, BCL11A, USP34, COMMD1, and OTX1 genes was found to be more common in the tDLBCL compared with dnDLBCL (P < 0.001). Furthermore, a high‐level amplification of 2p15–16.1 was also detected in the FL stage prior to transformation, indicating its importance during the transformation event. Quantitative real‐time PCR showed a higher level of amplification of REL, USP34, and COMMD1 (all involved in the NFκΒ‐pathway) compared with BCL11A, which indicates that the altered genes disrupting the NFκΒ pathway may be the driver genes of transformation rather than the previously suggested BCL11A. Moreover, a 17q21.33 amplification was exclusively found in tDLBCL, never in FL (P < 0.04) or dnDLBCL, indicating an upregulation of genes of importance during the later phase of transformation. Taken together, our study demonstrates potential genomic markers for disease progression to clinically more aggressive forms. We also confirm the importance of the TP53‐, CDKN2A‐, and NFκΒ‐pathways for the transformation from FL to DLBCL. © 2014 Wiley Periodicals, Inc.     

AA‐type amyloidosis in association with non‐Hodgkin's lymphoma following CMV viremia: Autopsy case

Amyloidosis in non‐Hodgkin's lymphoma (NHL) is known to be of the AL type, and AA‐type amyloidosis in NHL is extremely rare. Herein is reported an autopsy case of follicular lymphoma that transformed to diffuse large B‐cell lymphoma (DLBCL) in a relapse associated with systemic AA amyloidosis. CMV infection in an immunocompromised state with chemotherapy against DLBCL may have been involved in amyloid accumulation. The serum amyloid A (SAA)1 gene polymorphism, SAA1.2/1.3, might have also been another factor in this case, considering the risk of AA amyloidosis in Japanese patients with rheumatoid arthritis.     

Lymphotoxin α1β2 expression on B cells is required for follicular dendritic cell activation during the germinal center response

CD19‐deficient mice were used as a model to study follicular dendritic cell (FDC) activation because these mice have normal numbers of FDC‐containing primary follicles, but lack the ability to activate FDCs or form GCs. It was hypothesized that CD19 expression is necessary for B‐cell activation and upregulation of membrane lymphotoxin (mLT) expression, which promotes FDC activation. Using VCAM‐1 and FcγRII/III as FDC activation markers, it was determined that the adoptive transfer of CD19⁺ wild‐type B cells into CD19‐deficient hosts rescued GC formation and FDC activation, demonstrating that CD19 expression on B cells is required for FDC activation. In contrast, CD19⁺ donor B cells lacking mLT were unable to induce VCAM‐1 expression on FDCs, furthermore FcγRII/III upregulation was impaired in FDCs stimulated with mLT‐deficient B cells. VCAM‐1 expression on FDCs, but not FcγRII/III, was rescued when CD19‐deficient B cells expressing transgenic mLT were cotransferred into recipient mice with CD19⁺, mLT‐deficient B cells, suggesting that FDC activation requires the CD19‐dependent upregulation of mLT on activated B cells. Collectively, these data demonstrate that activated B cells are responsible for the initiation of FDC activation resulting in a microenvironment supportive of GC development and maintenance.     

Diffuse large B cell lymphoma with an interfollicular pattern of proliferation shows a favourable prognosis: a study of the Osaka Lymphoma Study Group

Wada N, Zaki M A A, Kohara M, Ogawa H, Sugiyama H, Nomura S, Matsumura I, Hino M, Kanakura Y, Inagaki H, Morii E & Aozasa K
(2012) Histopathology  60, 924–932
Diffuse large B cell lymphoma with an interfollicular pattern of proliferation shows a favourable prognosis: a study of the Osaka Lymphoma Study Group Aims: ]Diffuse large B cell lymphoma (DLBCL) occasionally shows an interfollicular pattern of proliferation (DLBCL‐IF) preserving lymphoid follicles. In this study, clinicopathological findings in 31 cases of DLBCL‐IF were analysed. Methods and results: The study group comprised 20 males and 11 females, with ages ranging from 41 to 87 (median 69) years. The primary site was lymph node in 25 cases, and unknown in six due to advanced stage at diagnosis. Eight cases were clinical Stage I, 10 were Stage II, four Stage III, and nine Stage IV. A polymorphous pattern of proliferation containing large B cells and inflammatory cells was found in about 60% of cases. The overall survival rate of the DLBCL‐IF patients was better than that of a DLBCL control group (log‐rank test; P < 0.05). Multivariate analysis revealed that an interfollicular pattern of proliferation showed marginal significance for favourable prognosis (P = 0.069). Immunohistochemical double staining with antibodies for HLA‐DR/CD68 (markers for M1‐tumour‐associated macrophage [M1‐TAM]) or CD163/CD68 (M2‐TAM) revealed that all DLBCL‐IF patients with a low M2 count were alive at the end of observation. Conclusions: These findings suggest that DLBCL‐IF is a clinicopathological entity distinct from ordinary DLBCL. The possible origin of tumour cells in DLBCL‐IF from marginal zone B cells is discussed.     

At diagnosis,diffuse large B‐cell lymphoma patients show impaired rituximab‐mediated NK‐cell cytotoxicity

Diffuse large B‐cell lymphoma (DLBCL) is the most common subtype of non‐Hodgkin's lymphoma in adults. It is generally treated by a combination of chemotherapy and CD20‐specific mAbs, such as rituximab, which act, at least partially, by activating antibody‐dependent cell‐mediated cytotoxicity (ADCC). ADCC involves NK cells, particularly the CD56^dim NK‐cell subset expressing CD16, the low affinity Fcγ receptor. Here, we show that CD16 expression levels are decreased in a cohort of 36 newly diagnosed DLBCL patients compared with those in 20 healthy controls (HCs). CD137, a co‐stimulatory molecule expressed on activated NK cells, was also expressed at lower levels in patients compared with controls. Cells sampled from our cohort also showed severely reduced degranulation activity when challenged with rituximab‐coated tumor cells, which could not be corrected by stimulation with high doses of IL‐2. These results suggest that rituximab‐induced NK‐cell ADCC could be defective in some DLBCL patients at diagnosis. These patients should be closely monitored and attempts made to improve their NK‐cell function.     

High‐resolution loss of heterozygosity screening implicates PTPRJ as a potential tumor suppressor gene that affects susceptibility to non‐hodgkin's lymphoma

We employed a Hidden‐Markov‐Model (HMM) algorithm in loss of heterozygosity (LOH) analysis of high‐density single nucleotide polymorphism (SNP) array data from Non‐Hodgkin's lymphoma (NHL) entities, follicular lymphoma (FL), and diffuse large B‐cell lymphoma (DLBCL). This revealed a high frequency of LOH over the chromosomal region 11p11.2, containing the gene encoding the protein tyrosine phosphatase receptor type J (PTPRJ). Although PTPRJ regulates components of key survival pathways in B‐cells (i.e., BCR, MAPK, and PI3K signaling), its role in B‐cell development is poorly understood. LOH of PTPRJ has been described in several types of cancer but not in any hematological malignancy. Interestingly, FL cases with LOH exhibited down‐regulation of PTPRJ, in contrast no significant variation of expression was shown in DLBCLs. In addition, sequence screening in Exons 5 and 13 of PTPRJ identified the G973A (rs2270993), T1054C (rs2270992), A1182C (rs1566734), and G2971C (rs4752904) coding SNPs (cSNPs). The A1182 allele was significantly more frequent in FLs and in NHLs with LOH. Significant over‐representation of the C1054 (rs2270992) and the C2971 (rs4752904) alleles were also observed in LOH cases. A haplotype analysis also revealed a significant lower frequency of haplotype GTCG in NHL cases, but it was only detected in cases with retention. Conversely, haplotype GCAC was over‐representated in cases with LOH. Altogether, these results indicate that the inactivation of PTPRJ may be a common lymphomagenic mechanism in these NHL subtypes and that haplotypes in PTPRJ gene may play a role in susceptibility to NHL, by affecting activation of PTPRJ in these B‐cell lymphomas. © 2013 Wiley Periodicals, Inc.     

B细胞特异性激活蛋白Pax-5在淋巴瘤组织中的表达

目的探讨B细胞特异性激活蛋白(BSAP)／Pax-5在淋巴瘤的表达情况及应用价值。方法按2001年WHO关于淋巴造血组织肿瘤分类标准收集102例弥漫性大B细胞淋巴瘤(DLBCL)、3例滤泡型淋巴瘤(FL)、3例黏膜相关淋巴组织结外边缘区B细胞淋巴瘤(MALT淋巴瘤)、1例结节性淋巴细胞为主型的霍奇金淋巴瘤(NLPHL)、10例间变性大细胞淋巴瘤(ALCL)和10例浆细胞瘤,用免疫组织化学LSAB法同步检测比较BSAP与CD20的表达情况。结果102例DLBCL全部表达CD20,100例表达BSAP,3例FL、3例MALT淋巴瘤和1例NLPHL BSAP和CD20全部阳性表达,10例ALCL、10例浆细胞瘤BSAP和CD20全部阴性表达。BSAP与CD20的表达差异无统计学意义。结论。BSAP/Pax-5是一种新的B细胞标记,阳性信号定位于细胞核,抗BSAP抗体在常规外科病理诊断工作中的应用价值有限。     

Polymorphisms in pattern‐recognition genes in the innate immunity system and risk of non‐Hodgkin lymphoma

The pattern‐recognition pathway plays an important role in infection recognition and immune responses, and previous studies have suggested an association between genetic variation in innate immunity genes and non‐Hodgkin lymphoma (NHL). We evaluated NHL risk associated with genetic variation in pattern‐recognition genes using data from a case–control study of NHL conducted in Connecticut women. Single nucleotide polymorphisms (SNPs) in 27 pattern‐recognition genes were genotyped in 432 Caucasian incident NHL cases and 494 frequency‐matched controls. Unconditional logistic regression was used to compute odds ratios (ORs) for NHL and common NHL subtypes in relation to individual SNPs and haplotypes. A gene‐based analysis that adjusted for the number of tagSNPs genotyped in each gene showed a significant association with overall NHL for the MBP gene (P = 0.028), with the diffuse large B‐cell lymphoma (DLBCL) subtype for the MASP2 gene (P = 0.011), and with the follicular lymphoma (FL) subtype for DEFB126 (P = 0.041). A SNP‐based analysis showed that MBP rs8094402 was associated with decreased risks of overall NHL (allele risk OR = 0.72, P‐trend = 0.0018), DLBCL (allele risk OR = 0.72, P‐trend = 0.036), and FL (allele risk OR = 0.67, P‐trend = 0.021), while MASP2 rs12711521 was associated with a decreased risk of DLBCL (allele risk OR = 0.57, P‐trend = 0.0042). We also observed an increased risk of FL for DEFB126 rs6054706 (allele risk OR = 1.39, P‐trend = 0.033). Our results suggest that genetic variation in pattern‐recognition genes is associated with the risk of NHL or specific NHL subtypes, but these preliminary findings require replication in larger studies. Mol. Mutagen. 2013. © 2012 Wiley Periodicals, Inc.     

Activation of the NF-kappaB signalling pathway in diffuse large B-cell lymphoma: clinical implications

Aim: To characterize the activation of the nuclear factor (NF)‐κB pathway in diffuse large B‐cell lymphoma (DLBCL) by immunohistochemistry. Methods and results: Sixty‐six DLBCLs treated with anthracycline‐containing chemotherapy were evaluated with antibodies against phosphorylated p65 (P‐p65), p65, p50, p52, IKKα, and phosphorylated IκB (P‐IκB). NF‐κB activation was based on the expression of P‐p65, P‐IκB, and nuclear expression of p65 or p52 in the tumour cells. P‐p65 and P‐IκB were expressed in 13 (20%) and 17 cases (26%), respectively. p65, p52 and IKKα were found in the cytoplasm. A correlation was found between expression of P‐p65 and P‐IκB (P < 0.0001), but not between the two subtypes of DLBCL [germinal centre B cell and non‐germinal centre (GC)]. P‐p65+ tumours showed a better response to chemotherapy (P = 0.025) and a trend to increased event‐free survival (P = 0.08). However, P‐IκB expression was not associated with either clinical response or survival. Bcl‐2 was not preferentially expressed on DLBCL tumours with NF‐κB activation, as determined by expression of P‐p65 and P‐IκB proteins. Conclusions: NF‐κB activation in DLBCL is preferentially mediated through the classical pathway and a novel mechanism involving phosphorylation of p65. Activation of NF‐κB by P‐p65 is associated with good prognosis. NF‐κB activation is not confined to non‐GC DLBCL exclusively.     

Focal follicular features in tonsillar diffuse large B-cell lymphomas: follicular lymphoma with diffuse areas or follicular colonization

Focal follicular features in diffuse large B-cell lymphomas (DLBCLs) are bound to raise the question of follicular lymphoma (FL) with diffuse areas, because the diagnosis of FL is based on the presence of follicular areas, even though focal. We report 7 cases of primary tonsillar DLBCLs with focal follicular features that presented with morphologic, immunohistochemical, and biological features distinct from those of FL. Histologically, these tumors were characterized by involvement of pericryptal follicles with adjacent dominant diffuse areas. Monomorphous large tumor cells were evenly spaced with abundant, often clear cytoplasm, and blastoid nuclei often with a delicate nuclear membrane. Importantly, residual germinal centers (GCs) were present in the form of either an intrafollicular GC remnant or an isolated GC in the midst of diffuse tumor. An extrafollicular and/or parafollicular growth pattern was also observed. Bcl-6 staining revealed a predominantly sporadic occurrence of Bcl-6(+) cells, comprising <50% of tumor cells, and none displayed diffusely dense collections (>75%) of Bcl-6(+) tumor cells characteristic of the GC or FL. Staining for CD10 was negative in 6 cases. Five of 7 patients were younger than 60, the median age of other patients with primary tonsillar DLBCL. No extratonsillar involvement was seen at 18 months after diagnosis. After chemotherapy or radiotherapy, complete remission was achieved with ease in all patients, but 2 patients who were treated with chemotherapy alone relapsed at 24 and 30 months. In conclusion, tonsillar DLBCL includes a small (10%) but distinct subgroup that warrants distinction from FL with predominant diffuse areas or de novo DLBCL. It appears that the focal follicular features in tonsillar DLBCL likely represent follicular colonization of marginal zone B-cell lymphoma, probably high-grade, if the possibility of FL is excluded.     

CXCR4 expression enhances diffuse large B cell lymphoma dissemination and decreases patient survival

The chemokine receptor CXCR4 has been implicated in the migration and trafficking of malignant B cells in several haematological malignancies. Over‐expression of CXCR4 has been identified in haematological tumours, but data concerning the role of this receptor in diffuse large B cell lymphoma (DLBCL) are lacking. CXCR4 is a marker of poor prognosis in various neoplasms, correlating with metastatic disease and decreased survival of patients. We studied CXCR4 involvement in cell migration in vitro and dissemination in vivo. We also evaluated the prognostic significance of CXCR4 in 94 biopsies of DLBCL patients. We observed that the level of expression of CXCR4 in DLBCL cell lines correlated positively with in vitro migration. Expression of the receptor was also associated with increased engraftment and dissemination, and decreased survival time in NOD/SCID mice. Furthermore, administration of a specific CXCR4 antagonist, AMD3100, decreased dissemination of DLBCL cells in a xenograft mouse model. In addition, we found that CXCR4 expression is an independent prognostic factor for shorter overall survival and progression‐free survival in DLBCL patients. These results show that CXCR4 mediates dissemination of DLBCL cells and define for the first time its value as an independent prognostic marker in DLBCL patients. Copyright © 2014 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd     

Recurrent mutations of NOTCH genes in follicular lymphoma identify a distinctive subset of tumours

Follicular lymphoma (FL) is one of the most common malignant lymphomas. The t(14;18)(q32;q21) translocation is found in about 80% of cases and plays an important role in lymphomagenesis. However, the molecular mechanisms involved in the development and transformation of this lymphoma are not fully understood. Gain‐of‐function mutations of NOTCH1 or NOTCH2 have recently been reported in several B cell lymphoid neoplasms but the role of these mutations in FL is not known. In this study we investigated the mutational status of these genes in 112 FLs. NOTCH1 and NOTCH2 mutations were identified in five and two cases, respectively (total 7/112, 6.3%). All mutations predicted for truncated protein in the PEST domain and were identical to those identified in other B cell lymphoid neoplasms. NOTCH‐mutated FL cases were characterized by lower frequency of t(14;18) (14% versus 69%, p = 0.01), higher incidence of splenic involvement (71% versus 25%, p = 0.02) and female predominance (100% versus 55%, p = 0.04). A diffuse large B cell lymphoma (DLBCL) component was more frequently identified in NOTCH‐mutated FL than in wild‐type cases (57% versus 18%, p = 0.03). These results indicate that NOTCH mutations are uncommon in FL but may occur in a subset of cases with distinctive, characteristic, clinicopathological features. Copyright © 2014 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.