Diagnostic methods for primary vitreoretinal lymphoma: A systematic review.

Primary vitreoretinal lymphoma is a potentially aggressive intraocular malignancy with poor systemic prognosis and sometimes significant diagnostic delays as it may masquerade as chronic uveitis. Despite the variety of diagnostic techniques, it is unclear which modality is most accurate in the diagnosis of PVRL. A systematic literature search was conducted on Ovid MEDLINE, EMBASE and the Cochrane Controlled Register of Trials for studies published between January, 2000, and June, 2023. Randomized controlled trials (RCTs) reporting on the following diagnostic tools used to diagnose patients with PVRL were included: cytology, flow cytometry, MYD88 L265P mutation, CD79B mutation, interleukin 10/interleukin-6 (IL-10/IL-6) ratio, polymerase chain reaction (PCR) for monoclonal immunoglobulin heavy chain (IgH) and immunoglobulin kappa light chain (IgK) rearrangements, and imaging findings. The aggregated sensitivity of each diagnostic modality was reported and compared using the chi-squared (χ2) test. A total of 662 eyes from 29 retrospective studies reporting on patients diagnosed with PVRL were included. An IL-10/IL-6 ratio greater than 1 had the highest sensitivity (89.39%, n = 278/311 eyes, n = 16 studies) for PVRL, where the sensitivity was not significantly different when only vitreous samples were drawn (88.89%, n = 232/261 eyes, n = 13 studies) compared to aqueous samples (83.33%, n = 20/24, n = 2) (p = 0.42). Flow cytometry of vitreous samples gave a positive result in 66/75 eyes (88.00%, n = 6 studies) with PVRL, and monoclonal IgH rearrangements on PCR gave a positive result in 354/416 eyes (85.10%, n = 20 studies) with PVRL. MYD88 L265P and CD79B mutation analysis performed poorly, yielding a positive result in 63/90 eyes (70.00%, n = 8 studies) with PVRL, and 20/57 eyes (35.09%, n = 4 studies) with PVRL, respectively. Overall, our systematic review found that an IL-10/IL-6 ratio greater or equal to one may provide the highest sensitivity in identifying patients with PVRL. Future studies are needed to employ multiple diagnostic tools to aid in the detection of PVRL and to further establish nuanced guidelines when determining the optimal diagnostic tool to use in diverse patient populations.

The Prognostic Significance of CD79B Mutation in Diffuse Large B-Cell Lymphoma: A Meta-analysis and Systematic Literature Review.

INTRODUCTION: Previous studies have shown that diffuse large B-cell lymphoma (DLBCL) subtype with both B-cell antigen receptor complex-associated protein beta chain (CD79B) and myeloid differentiation primary response 88 mutations (MYD88) had inferior outcome under standard immunochemotherapy. However, the prognostic significance of CD79B alone in DLBCL has not been fully elucidated. We conducted a meta-analysis to investigate the role of CD79B mutation on overall survival (OS) in patients with DLBCL. METHODS: We performed literature search in PubMed and Embase databases and followed PRISMA guidelines to select publications for analysis. The primary and secondary outcome was OS and progression-free survival (PFS) respectively. Hazard ratio (HR) for OS/PFS in CD79B mutant group with that in wild-type group in R-chemotherapy patients was either estimated using Cox proportional hazard model from the studies with individual participant level data or extracted from the original publication with aggregated results. RESULTS: Nine eligible studies with survival information according to CD79B mutation status were included in this meta-analysis. The pooled hazard ratio for OS was 1.38 (95% CI, 1.13-1.70; p = 0.0021) for CD79B mutation, providing evidence that CD79B mutation was unfavorable prognostic factor for survival in DLBCL patients treated with immunochemotherapy. We identified the inferior prognostic impact of CD79B mutation was independent from well-established prognostic model in DLBCL, International Prognostic Index. The predictive power of CD79B mutation was stronger than that of MYD88 mutation. CONCLUSION: This meta-analysis revealed that CD79B mutation could be a key biomarker for DLBCL disease progression and future mechanism-based target therapy in DLBCL needs to be studied.

Spatial transcriptome of a germinal center plasmablastic burst hints at MYD88/CD79B mutants-enriched diffuse large B-cell lymphomas.

The GC reaction results in the selection of B cells acquiring effector Ig secreting ability by progressing toward plasmablastic differentiation. This transition is associated with exclusion from the GC microenvironment. The aberrant expansion of plasmablastic elements within the GC fringes configures an atypical condition, the biological characteristics of which have not been defined yet. We investigated the in situ immunophenotypical and transcriptional characteristics of a nonclonal germinotropic expansion of plasmablastic elements (GEx) occurring in the tonsil of a young patient. Compared to neighboring GC and perifollicular regions, the GEx showed a distinctive signature featuring key regulators of plasmacytic differentiation, cytokine signaling, and cell metabolism. The GEx signature was tested in the setting of diffuse large B-cell lymphoma (DLBCL) as a prototypical model of lymphomagenesis encompassing transformation at different stages of GC and post-GC functional differentiation. The signature outlined DLBCL clusters with different immune microenvironment composition and enrichment in genetic subtypes. This report represents the first insight into the transcriptional features of a germinotropic plasmablastic burst, shedding light into the molecular hallmarks of B cells undergoing plasmablastic differentiation and aberrant expansion within the noncanonical setting of the GC microenvironment.

Discovery of a novel Igß and FcγRIIB cross-linking antibody, ASP2713, and its potential application in the treatment of systemic lupus erythematosus.

B cell-targeted therapies have evolved as established therapies for systemic lupus erythematosus (SLE); however, existing approaches still do not thoroughly satisfy clinical requirements due to limited efficacy against memory B cells, autoantibody-producing plasmablasts and disease heterogeneity. To provide a new treatment option for SLE, we created a novel anti-Igß antibody with enhanced affinity for Fc gamma receptor (FcγR) IIB called ASP2713. ASP2713 cross-reacted with both human and cynomolgus monkey Igß and showed increased binding affinity for human and monkey FcγRIIB compared to native human IgG1. This binding property allows dominant B cell binding and induction of intrinsic negative feedback signals. In human B cells, ASP2713 significantly and concentration-dependently induced FcγRIIB ITIM phosphorylation, while suppressing proliferation under B cell receptor stimulation. This pharmacological effect was also confirmed in in vitro B cell proliferation and antibody production assays using peripheral B cells isolated from patients with SLE. In a cynomolgus monkey tetanus toxoid-induced antibody production model, ASP2713 almost completely inhibited the increase in antigen-specific antibodies with superior efficacy to rituximab. Additionally, ASP2713 significantly suppressed recall antibody production in response to secondary tetanus toxoid immunization, indicating the memory B cell- and plasmablast-targeting potential of ASP2713. Our results suggest that ASP2713 may have therapeutic potential as a treatment for SLE, where B cells play a pathogenic role.

Characterising the Phenotypic Diversity of Antigen-Specific Memory B Cells Before and After Vaccination.

The diversity of B cell subsets and their contribution to vaccine-induced immunity in humans are not well elucidated but hold important implications for rational vaccine design. Prior studies demonstrate that B cell subsets distinguished by immunoglobulin (Ig) isotype expression exhibit divergent activation-induced fates. Here, the antigen-specific B cell response to tetanus toxoid (TTd) booster vaccination was examined in healthy adults, using a dual-TTd tetramer staining flow cytometry protocol. Unsupervised analyses of the data revealed that prior to vaccination, IgM-expressing CD27+ B cells accounted for the majority of TTd-binding B cells. 7 days following vaccination, there was an acute expansion of TTd-binding plasmablasts (PB) predominantly expressing IgG, and a minority expressing IgA or IgM. Frequencies of all PB subsets returned to baseline at days 14 and 21. TTd-binding IgG+ and IgA+ memory B cells (MBC) exhibited a steady and delayed maximal expansion compared to PB, peaking in frequencies at day 14. In contrast, the number of TTd-binding IgM+IgD+CD27+ B cells and IgM-only CD27+ B cells remain unchanged following vaccination. To examine TTd-binding capacity of IgG+ MBC and IgM+IgD+CD27+ B cells, surface TTd-tetramer was normalised to expression of the B cell receptor-associated CD79b subunit. CD79b-normalised TTd binding increased in IgG+ MBC, but remained unchanged in IgM+IgD+CD27+ B cells, and correlated with the functional affinity index of plasma TTd-specific IgG antibodies, following vaccination. Finally, frequencies of activated (PD-1+ICOS+) circulating follicular helper T cells (cTFH), particularly of the CXCR3-CCR6- cTFH2 cell phenotype, at their peak expansion, strongly predicted antigen-binding capacity of IgG+ MBC. These data highlight the phenotypic and functional diversity of the B cell memory compartment, in their temporal kinetics, antigen-binding capacities and association with cTFH cells, and are important parameters for consideration in assessing vaccine-induced immune responses.

Uncovering early events in primary Epstein-Barr virus infection using a rabbit model.

Epstein-Barr virus (EBV) is an oncogenic herpesvirus implicated in the pathogenesis of several malignant and non-malignant conditions. However, a number of fundamental aspects about the biology of EBV and the mechanism(s) by which this virus induces pathology remain unknown. One major obstacle has been the lack of a suitable animal model for EBV infection. In this study, using our recently established rabbit model of EBV infection, we examined the early events following primary EBV infection. We show that, both immunocompetent and immunosuppressed animals were readily susceptible to EBV infection. However, immunosuppressed animals showed marked splenomegaly and widespread infection. Following EBV infection, the virus primarily targeted naïve IgM+, CD20+, CD21+ and CD79a+ B cells. Infected cells expressed varying sets of viral latent/lytic gene products. Notably, co-expression of latent and lytic proteins in the same cell was not observed. Infected cells in type 0/1 latency (EBERs+), were small and proliferating (Ki67+). By contrast, cells in type 2/3 latency (LMP1+), were large, non-proliferating (Ki-67-) and p53+. Although infected B-cells were widely present in splenic follicles, they did not express germinal center marker, BCL-6. Taken together, this study shows for the first time, some of the early events following primary EBV infection.

Bruton's tyrosine kinase inhibition induces rewiring of proximal and distal B-cell receptor signaling in mice.

Bruton's tyrosine kinase (Btk) is a crucial signaling molecule in BCR signaling and a key regulator of B- cell differentiation and function. Btk inhibition has shown impressive clinical efficacy in various B-cell malignancies. However, it remains unknown whether inhibition additionally induces changes in BCR signaling due to feedback mechanisms, a phenomenon referred to as BCR rewiring. In this report, we studied the impact of Btk activity on major components of the BCR signaling pathway in mice. As expected, NF-κB and Akt/S6 signaling was decreased in Btk-deficient B cells. Unexpectedly, phosphorylation of several proximal signaling molecules, including CD79a, Syk, and PI3K, as well as the key Btk-effector PLCγ2 and the more downstream kinase Erk, were significantly increased. This pattern of BCR rewiring was essentially opposite in B cells from transgenic mice overexpressing Btk. Importantly, prolonged Btk inhibitor treatment of WT mice or mice engrafted with leukemic B cells also resulted in increased phosho-CD79a and phospho-PLCγ2 in B cells. Our findings show that Btk enzymatic function determines phosphorylation of proximal and distal BCR signaling molecules in B cells. We conclude that Btk inhibitor treatment results in rewiring of BCR signaling, which may affect both malignant and healthy B cells.

Composite CD79A/CD40 co-stimulatory endodomain enhances CD19CAR-T cell proliferation and survival.

Adoptively transferred CD19 chimeric antigen receptor (CAR) T cells have led to impressive clinical outcomes in B cell malignancies. Beyond induction of remission, the persistence of CAR-T cells is required to prevent relapse and provide long-term disease control. To improve CAR-T cell function and persistence, we developed a composite co-stimulatory domain of a B cell signaling moiety, CD79A/CD40, to induce a nuclear translocating signal, NF-κB, to synergize with other T cell signals and improve CAR-T cell function. CD79A/CD40 incorporating CD19CAR-T cells (CD19.79a.40z) exhibited higher NF-κB and p38 activity upon CD19 antigen exposure compared with the CD28 or 4-1BB incorporating CD19CAR-T cells (CD19.28z and CD19.BBz). Notably, we found that CD19.79a.40z CAR-T cells continued to suppress CD19+ target cells throughout the co-culture assay, whereas a tendency for tumor growth was observed with CD19.28z CAR-T cells. Moreover, CD19.79a.40z CAR-T cells exhibited robust T cell proliferation after culturing with CD19+ target cells, regardless of exogenous interleukin-2. In terms of in vivo efficiency, CD19.79a.40z demonstrated superior anti-tumor activity and in vivo CAR-T cell proliferation compared with CD19.28z and CD19.BBz CD19CAR-T cells in Raji-inoculated mice. Our data demonstrate that the CD79A/CD40 co-stimulatory domain endows CAR-T cells with enhanced proliferative capacity and improved anti-tumor efficacy in a murine model.

TNF receptor-associated factor 3 restrains B-cell receptor signaling in normal and malignant B cells.

TRAF3 has diverse signaling functions, which vary by cell type. Uniquely in B lymphocytes, TRAF3 inhibits homeostatic survival. Highlighting the role of TRAF3 as a tumor suppressor, loss-of-function TRAF3 mutations are associated with human B-cell malignancies, while B-cell-specific deletion of TRAF3 in mice leads to autoimmunity and lymphoma development. The role of TRAF3 in inhibiting noncanonical NF-κB activation, CD40 and BAFF-R signaling to B cells is well documented. In contrast, TRAF3 enhances many T-cell effector functions, through associating with and enhancing signaling by the T-cell receptor (TCR)-CD28 complex. The present study was designed to determine the role of TRAF3 in signaling via the B-cell antigen receptor (BCR). The BCR is crucial for antigen recognition, survival, proliferation, and antibody production, and defects in BCR signaling can promote abnormal survival of malignant B cells. Here, we show that TRAF3 is associated with both CD79B and the BCR-activated kinases Syk and Btk following BCR stimulation. BCR-induced phosphorylation of Syk and additional downstream kinases was increased in TRAF3-/- B cells, with regulation observed in both follicular and marginal zone B-cell subsets. BCR stimulation of TRAF3-/- B cells resulted in increased surface expression of MHC-II, CD80, and CD86 molecules. Interestingly, increased survival of TRAF3-/- primary B cells was resistant to inhibition of Btk, while TRAF3-deficient malignant B-cell lines showed enhanced sensitivity. TRAF3 serves to restrain normal and malignant BCR signaling, with important implications for its role in normal B-cell biology and abnormal survival of malignant B cells.

CD79a promotes CNS-infiltration and leukemia engraftment in pediatric B-cell precursor acute lymphoblastic leukemia.

Central nervous system (CNS) involvement remains a challenge in the diagnosis and treatment of acute lymphoblastic leukemia (ALL). In this study, we identify CD79a (also known as Igα), a signaling component of the preB cell receptor (preBCR), to be associated with CNS-infiltration and -relapse in B-cell precursor (BCP)-ALL patients. Furthermore, we show that downregulation of CD79a hampers the engraftment of leukemia cells in different murine xenograft models, particularly in the CNS.

Targeting CD79b for Chimeric Antigen Receptor T-Cell Therapy of B-Cell Lymphomas.

BACKGROUND: Although chimeric antigen receptor (CAR) T-cell therapy targeting antigens expressed in refractory and relapsed non-Hodgkin B-cell lymphoma, such as CD19 and CD22, has achieved encouraging clinical effects, some patients fail to attain remission, or relapse after CAR T-cell therapy, which has been ascribed to the loss of the target antigens. OBJECTIVE: To evaluate CD79b as an alternative target for CAR T-cell B-cell lymphoma therapy. PATIENT AND METHODS: The expression of CD79b in different B-cell lymphomas was determined. Anti-CD79b CAR T-cells expressing one of two different CARs were generated, and a series of in vitro and in vivo experiments were conducted to assess the CAR T-cell function. RESULTS: We found that CD79b was extensively expressed on the tumor cells of patients with various types of lymphoma regardless of stage, subtype, and cytogenetic and molecular features. Anti-CD79b CAR T-cells were highly specific and effective for the treatment of B-cell lymphomas. CONCLUSIONS: Our data indicate that CD79b could be used as a target for CAR T-cell therapy of B-cell lymphomas, and further clinical development is warranted.

Phosphoflow Protocol for Signaling Studies in Human and Murine B Cell Subpopulations.

BCR signaling, involving phosphorylation of various downstream molecules, including kinases, lipases, and linkers, is crucial for B cell selection, survival, proliferation, and differentiation. Phosphoflow cytometry (phosphoflow) is a single-cell-based technique to measure phosphorylated intracellular proteins, providing a more quantitative read-out than Western blotting. Recent advances in phosphoflow basically allow simultaneous analysis of protein phosphorylation in B cell (sub)populations, without prior cell sorting. However, fixation and permeabilization procedures required for phosphoflow often affect cell surface epitopes or mAb conjugates, precluding the evaluation of the phosphorylation status of signaling proteins across different B cell subpopulations present in a single sample. In this study, we report a versatile phosphoflow protocol allowing extensive staining of B cell subpopulations in human peripheral blood or various anatomical compartments in the mouse, starting from freshly isolated or frozen cell suspensions. Both human and mouse B cell subpopulations showed different basal and BCR stimulation-induced phosphorylation levels of downstream signaling proteins. For example, peritoneal B-1 cells and splenic marginal zone B cells exhibited significantly increased basal (ex vivo) signaling and increased responsiveness to in vitro BCR stimulation compared with peritoneal B-2 cells and splenic follicular B cells, respectively. In addition, whereas stimulation with anti-IgM or anti-Igκ L chain Abs resulted in strong pCD79a and pPLCγ2 signals, IgD stimulation only induced CD79a but not pPLCγ2 phosphorylation. In summary, the protocol is user friendly and quantifies BCR-mediated phosphorylation with high sensitivity at the single-cell level, in combination with extensive staining to identify individual B cell development and differentiation stages.

Molecular and phenotypic characterization of an early T-cell precursor acute lymphoblastic lymphoma harboring PICALM-MLLT10 fusion with aberrant expression of B-cell antigens.

T-cell acute lymphoblastic leukemia/lymphoma (T-ALL/LBL) is usually diagnosed based on the presence of immature lymphoid marker terminal deoxynucleotidyl transferase (TdT), and T-cell specific markers, specifically CD3, by immunohistochemistry (IHC) staining on bone marrow and/or extramedullary tissue. We present a novel, TdT and CD3 negative, aggressive early T-cell precursor LBL (ETP-LBL) initially misdiagnosed as a high grade B-cell lymphoma due to expression of CD79a and the erroneous detection of BCL2/IGH fusion. The patient was eventually evaluated using molecular diagnostic techniques, including fluorescence in situ hybridization (FISH) and next generation sequencing (NGS) assays that demonstrated PICALM-MLLT10 fusion and a NOTCH1 mutation in the absence of BCL2/IGH fusion. The use of NGS, specifically mate-pair sequencing (MPseq), subsequently confirmed an in-frame PICALM-MLLT10 fusion. Our retrospective analysis showed that PICALM-MLLT10 fusion has no association with CD3/TdT negativity, as 6/49 T-ALL/LBL cases from Mayo Clinic database (01/1998-09/2018), including this case, were noted to have PICALM-MLLT10 fusion; however, none of the other cases were associated with CD3/TdT negativity. We emphasize the importance of a comprehensive hematopathologic evaluation including multiple molecular studies for the appropriate interrogation and classification of a difficult acute leukemia diagnosis, and to prevent potential diagnostic errors of clinical significance.

Anaplastic variant of diffuse large B-cell lymphoma: Reappraisal as a nodal disease with sinusoidal involvement.

Anaplastic variant (av) of diffuse large B-cell lymphoma (DLBCL) is morphologically defined in the 2017 World Health Organization classification, but still an enigmatic disease in its clinicopathologic distinctiveness, posing the differential diagnostic problem from gray zone lymphoma (GZL) and classic Hodgkin lymphoma (cHL). Thirty-one cases previously diagnosed as avDLBCL were reassessed. Of these, 27 (87%) and 4 (13%) were node-based and extranodal diseases, respectively. They were further reclassified into nodal avDLBCL (n = 18), nodal CD30+ DLBCL with T-cell/histiocyte-rich large B-cell lymphoma-like features (CD30+ DLBCL-THRLBCL) (n = 6), GZL with features intermediate between DLBCL and cHL (n = 3) and CD30+ extranodal DLBCL, NOS (n = 4). The nodal avDLBCL cases had a sheet-like proliferation of large cells and/or Hodgkin/Reed-Sternberg (HRS)-like cells in 12 (67%) notably with a sinusoidal pattern in 16 (89%). They showed an expression of CD20 and/or CD79a in all and CD30 in 15 of 18. All of them were negative for PD-L1 on tumor cells, although HRS-like cells showed negativity or partial loss of other B-cell markers to varying degrees. The present study highlighted the distinctiveness of the nodal avDLBCL with sinusoidal pattern, but without neoplastic PD-L1 expression, which provide refined diagnostic criteria for a more precise pathologic and clinical characterization of this disease.

Classification, bacteriological findings, and analysis of sex hormone receptors and cytokine expression in mammary lesions of abattoir sows.

Mammary lesions in sows can prevent suckling piglets from consuming colostrum that provides fundamental nutrients and protective immunity. Although mammary gross lesions are frequently found in sows at farms or slaughterhouses, with the exception of mastitis, they have received little research attention. In this study, we investigated mammary lesions observed in South Korean sows between 2015 and 2016. Mammary tissue samples of 82 sows showing gross lesions during meat inspection were histologically classified and immunohistochemical analysis was conducted to assess the expression of estrogen receptor (ER)-α, ER-ß, and progesterone receptor (PR) for mammary hyperplastic lesions as well as that of cluster of differentiation (CD) 3, CD79a, interleukin (IL)-1α, IL-1ß, IL-6, and IL-8 for mastitis. Furthermore, 20 swab samples were cultured, and the isolated bacteria were identified using polymerase chain reactions for 16S ribosomal RNA genes. The lesions were classified as hyperplasia, mastitis, or hyperplasia with mastitis. Immunohistochemistry results revealed that there was neither expression of ER-α nor of ER-ß, but all examined hyperplastic samples expressed PR. In addition, there was a significant correlation between CD3 and IL-1ß expressions, as well as between IL-1ß and IL-6 expressions. Regarding the identity of the isolated bacteria, Pseudomonas spp. were most frequently detected. The results of this study have revealed the incidence and characteristics of porcine mammary lesions.

Intracranial Cell Lymphomas That Mimic Meningiomas: Case Report To Understand Complex Genetic, Radiologic, and Histopathologic Entities.

BACKGROUND: We describe a patient affected by a T-cell primary central nervous system lymphoma (PCNSL) with highly aberrant specific B-cell markers (CD79a and CD20). An unusual imaging presentation leads us to misdiagnose this lesion for a meningioma and perform surgical resection. CASE DESCRIPTION: We think that this infrequent anatomic presentation might be due to the aberrant specific B-cell markers (CD79a and CD20) genotype expression. We believe this case to be relevant in order to appreciate the diagnosis of cerebral lymphomas according to various presentations. We wonder whether it was not the aberrant genotype that contributed to this quirky presentation and ultimately if surgery in PCNSL should not be discussed? CONCLUSIONS: Furthermore, this case calls attention to the complexity of lineage assignment, imaging diagnosis, and treatment strategy in PCNSL.

MYD88, CARD11, and CD79B Oncogenic Mutations are Rare Events in the Indian Cohort of De Novo Nodal Diffuse Large B-Cell Lymphoma.

Diffuse large B-cell lymphoma (DLBCL) has a heterogenous biological behavior, and the western literature has reported activating oncogenic mutations in myeloid differentiation primary response gene 88 (MYD88), in conjunction with B-cell receptor signaling pathway genes, CARD11 and CD79B as the driving force for activating the NF-κB pathway implicated in the pathogenesis of DLBCL. The mutation profile of MYD88 genes was evaluated by Sanger sequencing in a cohort of 97 patients [DLBCL (N=55), non-DLBCL lymphomas (N=30), reactive lymphadenopathy (N=10), and 2 cases of lymphoplasmacytic lymphoma (positive control)]. The mutation profile of CARD11 and CD79B were evaluated in 70 patients [DLBCL (N=30), non-DLBCL lymphomas (N=30), and reactive lymphadenopathy (N=10). MYD88 and NF-κB mRNA expression was also evaluated by quantitative reverse transcriptase polymerase chain reaction. These 55 cases of DLBCL were classified into germinal center B-cell and activated B-cell phenotypes using Hans algorithm, of which 58% were of activated B-cell phenotype and 42% were of germinal center B-cell phenotype. MYD88 mutation was seen in 3.6% (2/55) of DLBCL cases, indicating a lower frequency in Indian de novo DLBCL. The mutations detected were novel 33 bp deletion g.7735_7767del (p.V294_S305del) and a splice-acceptor site mutation in exon 5 of MYD88, different from the reported hotspot mutation MYD88 L265P. CARD11 and CD79B mutations were absent in DLBCL and other lymphoma subtypes. MYD88 transcript expression did not correlate with mutational status. NF-κB showed significant overexpression in MYD88 mutation-negative (P=0.004) DLBCL cases indicating that its regulation is independent of MYD88, CARD11, and CD79B mutations, implying the existence of alternative activating pathways. In silico analysis of 2 novel mutations predicted disruptive structural changes in the B-B loop of the translated protein whose biological significance needs further evaluation.

Canine Splenic Nodular Lymphoid Lesions: Immunophenotyping, Proliferative Activity, and Clonality Assessment.

Canine splenic lymphoid nodules are currently classified as indolent lymphomas (marginal zone lymphoma [MZL], mantle cell lymphoma [MCL]) or nodular hyperplasia (lymphoid [LNH] or complex [CNH] type). Their differentiation can be difficult on morphology, because of similar histologic appearance and poorly defined diagnostic criteria. Thirty-five surgical samples of splenic lymphoid nodules were reviewed in order to assess the diagnostic contribution of immunophenotyping, proliferative activity and clonality (PARR) in differentiating between hyperplastic and neoplastic lesions. Proliferative activity was evaluated by double immunolabeling for Ki-67 and CD79a, in order to separately assess the proliferative activity of B cells and non-B cells. Definitive diagnoses were MZL ( n = 11), MCL ( n = 4), LNH ( n = 10), and CNH ( n = 10). The overall concordance between histology and PARR was above 90%. Lymphomas had a significantly higher percentage of CD79a-positive areas (mean, 36.30%; P = .0004) and a higher B-cell proliferative activity (median Ki-67 index, 5.49%; P = .0012). The threshold value most accurately predicting a diagnosis of lymphoma was ≥28% of B-cell areas, with a Ki-67 index above 3%. Dogs were monitored for a median follow-up time of 870 days (IQR, 569-1225), and no relapses were documented. Overall median survival time was 1282 days. The combination of histology, immunohistochemistry and PARR can improve the diagnostic accuracy for canine splenic lymphoid nodules, although the long-term behavior of these lesions appears similar.