Clinical implications of nodal marginal zone B-cell lymphoma among Japanese: study of 65 cases

The clinical significance of increased large cells in marginal zone lymphoma

Marginal zone lymphoma (MZL) is a primary, indolent small B-cell lymphoma. Subtypes include nodal, splenic, and those of extranodal mucosa-associated lymphoid tissue (MALT). These are slow growing and generally exhibit low rates of transformation to diffuse large B-cell lymphoma (DLBCL). At initial diagnosis, there can be an increase in large cells (LCs) that does not meet criteria for DLBCL. Prior studies have noted this finding, but the clinical significance of these LCs has not been well established. A total of 161 cases of MZL from 1994 to 2021 were evaluated, including all subtypes. There were 33 cases with increased LCs (>10 LCs per high-power field [hpf]), with the majority containing >15 LCs/hpf (28/33) and 128 cases without increased LCs. Cases with increased LCs were significantly more likely to have a Ki-67 proliferation index of ≥30% (P < .0001). Overall survival was not significantly different between the groups but progression-free survival was significantly worse in the LC group (P < .0001). MZL with increased LCs was also associated with a higher stage at diagnosis (P = .0035), was more likely to transform to DLBCL (P = .0016), and had a greater frequency of relapse (P < .0001). Subgroup analysis showed that both nodal and MALT LC groups had a worse progression-free survival and a higher rate of relapse than their standard nodal and MALT lymphoma counterparts, but only within the MALT subgroup did the LC cases present at a higher stage and have a higher rate of transformation to DLBCL than the standard cases. Although larger studies are needed for validation, these results suggest that the presence of LCs in MZL may serve as a useful prognostic indicator and potentially help guide clinical decision-making.

Retrospective characterization of nodal marginal zone lymphoma

Nodal marginal zone lymphoma (NMZL) is a rare non-Hodgkin B-cell lymphoma that has historically been difficult to define, though is now formally recognized by the World Health Organization Classification. To better characterize the clinical outcomes of patients with NMZL, we reviewed a sequential cohort of 187 patients with NMZL to describe baseline characteristics, survival outcomes, and time-to-event data. Initial management strategies were classified into five categories: observation, radiation, anti-CD20 monoclonal antibody therapy, chemoimmunotherapy, or other. Baseline Follicular Lymphoma International Prognostic Index scores were calculated to evaluate prognosis. A total of 187 patients were analyzed. The five-year overall survival was 91% (95% confidence interval [CI], 87-95), with a median follow-up time of 71 months (range, 8-253) among survivors. A total of 139 patients received active treatment at any point, with a median follow-up time of 56 months (range, 13-253) among survivors who were never treated. The probability of remaining untreated at five years was 25% (95% CI, 19-33). For those initially observed, the median time to active treatment was 72 months (95% CI, 49-not reached). For those who received at least one active treatment, the cumulative incidence of receiving a second active treatment at 60 months was 37%. Transformation to large B-cell lymphoma was rare, with a cumulative incidence of 15% at 10 years. In summary, our series is a large cohort of uniformly diagnosed NMZL with detailed analyses of survival and time to event analyses. We showed that NMZL commonly presents as an indolent lymphoma for which initial observation is often a reasonable strategy.

Eosinophil-rich variant of nodal marginal zone lymphoma: a clinicopathological study of 11 cases

AIMS

Tissue eosinophilia is commonly observed in T-cell and classic Hodgkin lymphomas, but rarely in B-cell lymphomas. Herein, we present the first report of a case series on nodal marginal zone lymphoma (NMZL) with tissue eosinophilia.

METHODS AND RESULTS

All 11 patients in this study had nodal disease at primary presentation. The mean age at diagnosis was 64 years. The mean follow-up period was 39 months, and all patients were alive. Nine of the 11 patients (82%) showed no recurrence, but the other two patients experienced recurrence in the lymph nodes or skin. Marked eosinophilic infiltration was observed in all biopsied lymph nodes. Nine of the 11 patients had a preserved nodular architecture with expanded interfollicular areas. The other two patients showed diffuse lymphoma cell infiltration with effacement of nodal architecture. One of them was diagnosed as having diffuse large B-cell lymphoma transformed from NMZL because large cells accounted for >50% of the lymphoma cells and formed sheet-like patterns. Cells were positive for CD20 and BCL2 and negative for CD5, CD10, and BCL6. Some patients showed myeloid cell nuclear differentiation antigen (MNDA) positivity. All patients showed B-cell monoclonality via flow cytometry, southern blotting, and/or polymerase chain reaction (PCR).

CONCLUSION

All patients showed distinctive morphological features and could be misdiagnosed with peripheral T-cell lymphoma due to their eosinophil-rich backgrounds. The predominance of B cells, absence of histiocytes, and high endothelial venules in the interfollicular areas are key factors for diagnosis. B-cell monoclonality is the most reliable evidence of differentiation. We designated this type of lymphoma as an eosinophil-rich variant of NMZL.

Causes of Death in Low Grade B-Cell Lymphomas in the Rituximab Era: A Prospective Cohort Study

Mortality for patients with marginal zone and indolent B-cell lymphoma is largely unrelated to lymphoma in the first decade from diagnosis.

Early progression or retreatment within 24 months of diagnosis is strongly associated with increased risk of lymphoma-related mortality.

Low-grade B-cell lymphomas other than follicular and small lymphocytic lymphoma (LGBCL) account for 10% of all B-cell non-Hodgkin lymphomas. Despite improvements in survival outcomes for these patients, little is known about cause of death (COD) in the rituximab era. For a better understanding, we studied 822 newly diagnosed patients with marginal zone, lymphoplasmacytic, and unclassifiable low-grade B-cell lymphoma prospectively enrolled in the University of Iowa/Mayo Clinic Specialized Program of Research Excellence Molecular Epidemiology Resource from 2002 to 2015. COD was assigned based on medical record review using a standard protocol. At a median follow-up of 107 months, 219 (27%) patients had died. The incidence of lymphoma-related deaths when pooling across subtypes was lower than non–lymphoma-related deaths (10-year incidence, 8.0%; 95% confidence interval [CI]: 6.2-10.4 vs 13.6%; 95% CI: 11.2-16.6). The incidence of lymphoma-related deaths varied by subtype, ranging from 3.7% at 10 years in extranodal marginal zone lymphoma to 19.3% in lymphoplasmacytic lymphoma/Waldenström macroglobulinemia. Patients with early progression or retreatment events, defined using event-free survival at 24 months from diagnosis, had significantly higher likelihood of lymphoma-related death compared with patients without early events (10-year estimate: 19.1% vs 5.1%, respectively; P < .001), whereas the rates for non–lymphoma-related death were comparable in patients with or without early events (10-year estimates: 11.0% vs 15.3%, respectively). In conclusion, the most common COD in LGBCLs in the first decade after diagnosis was for causes other than lymphoma. Progression or retreatment within the first 2 years of diagnosis was a strong predictor for risk of lymphoma-related death.

Complexities in the diagnosis of large B-cell lymphomas, classic Hodgkin lymphomas and overlapping peripheral T-cell lymphomas simplified: An evidence-based guide

The diagnosis of a large B-cell lymphoma and classic Hodgkin lymphoma (CHL) is often straightforward. However, in select circumstances, these simple diagnoses can be quite complex. In part, diagnostic difficulty may be due to uncertainty in the evaluation of morphologic and immunophenotypic features along a biologic continuum, or alternatively arise from uncertainty in predicting the behavior and outcomes of patients. Here, we systematically discuss and review areas of diagnostic difficulty in the diagnosis of large B-cell lymphomas (LBCL), classic Hodgkin lymphomas (CHL) and peripheral T-cell lymphomas (PTCL). We provide careful data-driven analyses and evidence-based approaches to help guide pathologists and clinicians. We discuss: 1) marginal zone lymphomas with increased large cells versus diffuse large B-cell lymphoma (DLBCL), 2) chronic lymphocytic leukemia with expanded proliferation centers versus diffuse large B-cell lymphoma (DLBCL), 3) chronic lymphocytic leukemia with Hodgkin/Reed-Sternberg-like cells versus CHL arising from chronic lymphocytic leukemia, 4) complex cases of follicular lymphoma versus DLBCL, 5) PTCL with large B-cell proliferations versus PTCL with LBCL, 6) PTCL with Hodgkin/Reed-Sternberg-like cells versus CHL, and finally 7) blastoid/pleomorphic mantle cell lymphoma versus DLBCL. Our evidence and data driven approach may serve as a useful diagnostic guide.

Marginal zone B-cell lymphoma: lessons from Western and Eastern diagnostic approaches

Marginal zone B-cell lymphomas (MZLs) are a group of clinically indolent B-cell lymphomas postulated to derive from memory B lymphocytes in the 'marginal zone' of secondary lymphoid tissue. Today, MZL is recognised as a nosological umbrella term encompassing distinct entities with some shared phenotypic and genotypic features, including extranodal marginal zone B-cell lymphoma (EMZL) or mucosa-associated lymphoid tissue (MALT) lymphoma, splenic MZL, and nodal MZL, accounting for approximately 70%, 20%, and 10% of MZLs, respectively. These lymphomas share some phenotypic and genotypic features and have some variants and related provisional diseases, but are different in regards to their clinical and molecular characteristics. In addition, they are frequently associated with chronic antigenic stimulation represented either by infectious agents, particularly bacteria and viruses, or autoimmune diseases as exemplified by Sjögren syndrome, Hashimoto thyroiditis, and newly recognised IgG4-related disease. Furthermore, several chromosomal translocations have been identified in EMZL. In this review, we will focus on the updated histopathological criteria and the main problems with differential diagnoses in order to aid the diagnostic approach in our routine practice.

Antiphospholipid antibodies associated with nodal marginal zone lymphoma and its progression to diffuse large B-cell lymphoma-A case report

An association between autoimmune events, as well as the development of antiphospholipid (aPL) antibodies and lymphoproliferative disorders is well recognized. We present the patient with coagulation abnormalities and non-Hodgkin lymphoma (NHL), primarily diagnosed as nodal marginal zone B-cell lymphoma (NMZL), and in relapse as diffuse large B-cell lymphoma (DLBCL). In the follow-up period, the patient simultaneously developed different aPL antibodies. The presence of aPL antibodies in NHL is frequent but it is not common in the NMZL. The aim of the present case report is to highlight the possible underlying increase of aPL antibodies in NMZL patients with coagulation tests abnormalities.

The bendamustine plus rituximab regimen is active against primary nodal marginal zone B-cell lymphoma

Primary nodal marginal zone lymphoma (NMZL) is a rare disease. There is no current consensus on how to treat it. The bendamustine plus rituximab (BR) regimen is effective for the treatment of follicular and other indolent lymphomas, but its efficacy in NMZL is not known. We analyzed the outcome of 14 patients diagnosed with NMZL (median age 67 years) who were treated with 375 mg/m² of rituximab on day 1 and 90 mg/m² of bendamustine on days 1 and 2. The overall and complete response rates were 93% and 71%, respectively. Major toxicity (grade 3/4 neutropenia) occurred in 5% of treatment courses. After a median follow-up of 22 months (range: 18-55), the overall survival and the free survival rates were 100% and 93%, respectively. None of the patients showing a complete or partial response developed secondary myelodysplastic syndrome/acute myeloid leukemia. Bendamustine plus rituximab was found to be an active and well-tolerated regimen leading to the rapid control of disease.

The Comparative Diagnostic Features of Canine and Human Lymphoma

The non-Hodgkin lymphomas (NHLs) are a heterogeneous family of lymphoid malignancies that are among the most common neoplasms of both dogs and humans. Owing to shared molecular, signaling, incidence, and pathologic features, there is a strong framework supporting the utilization of canine lymphoma as a comparative, large animal model of human NHL. In alignment with the biologic similarities, the current approach towards the diagnosis and classification of canine lymphoma is based upon the human World Health Organization guidelines. While this approach has contributed to an increasing appreciation of the potential biological scope of canine lymphoma, it has also become apparent that the most appropriate diagnostic philosophy must be multimodal, namely by requiring knowledge of microscopic, immunophenotypic, and clinical features before establishing a final disease diagnosis. This review seeks to illustrate the comparative similarities and differences in the diagnosis of canine lymphoma through the presentation of the microscopic and immunophenotypic features of its most common forms.

Optimizing therapy for nodal marginal zone lymphoma

Nodal marginal zone lymphoma (NMZL) is a rare form of indolent small B-cell lymphoma which has only been clearly identified in the last 2 decades and which to date remains incurable. Progress in therapeutic management has been slow, largely due to the very small number of patients treated and the heterogeneity of treatments administered; thus, standard-of-care treatment is currently nonspecific for this lymphoma entity. In this review, treatments routinely used to manage adult NMZL patients are presented, principally based on immunochemotherapy (when treatment is needed). Biological research behind the key axes of agents currently under development is described; development of novel agents is heavily based on data from gene profiling and genome-wide sequencing research, uncovering a number of critical deregulated pathways specific to NMZL tumors. These include B-cell receptor, JAK/STAT, NF-κB, NOTCH, and Toll-like receptor signaling pathways, as well as intracellular processes such as the cell cycle, chromatin remodeling, and transcriptional regulation in terms of epigenetic modifiers, histones, or transcriptional co-repressors, along with immune escape via T-cell-mediated tumor surveillance. These pathways are examined in detail and a projection of how the field may evolve in the near future for an efficient personalized treatment approach for NMZL patients is presented.

Management of the marginal zone lymphomas

Marginal zone lymphomas (MZL) represent around 8 % of all non-Hodgkin lymphomas. During the last decades a number of studies have addressed the mechanisms underlying the disease development. Extranodal MZL lymphoma usually arises in mucosal sites where lymphocytes are not normally present from a background of either autoimmune processes, such as Hashimoto thyroiditis or Sjögren syndrome or chronic infectious conditions. In the context of a persistent antigenic stimulation, successive genetic abnormalities can progressively hit a B-cell clone among the reactive B-cells of the chronic inflammatory tissue and give rise to a MALT lymphoma. The best evidence of an etiopathogenetic link is available for the association between Helicobacter pylori-positive gastritis and gastric MALT lymphoma. Indeed, a successful eradication of this micro-organism with antibiotics can be followed by gastric MALT lymphoma regression in more than 2/3 of cases. Other microbial agents have been implicated in the pathogenesis of MZL arising in the skin (Borrelia burgdorferi), in the ocular adnexa (Chlamydophila psittaci), and in the small intestine (Campylobacter jejuni). The prevalence of hepatitis C virus (HCV) has also been reported higher in MZL patients (particularly of the splenic type) than in the control population, suggesting a possible causative role of the virus. In non-gastric MALT lymphoma and in splenic MZL the role of the antimicrobial therapy is, however, less clear. This review summarizes the recent advances in Marginal Zone Lymphomas, addressing the critical points in their diagnosis, staging and clinical management.

MicroRNA profiling of low-grade and transformed nodal marginal zone lymphoma reveals a similar signature pattern distinct from diffuse large B cell lymphoma

BACKGROUND/AIMS

As critical post-transcriptional regulators of gene expression, microRNAs are involved in several cellular processes of vital impact including cell growth and apoptosis. Many hematologic malignancies exhibit distinct microRNA signatures. MicroRNA implication in the pathogenesis of nodal marginal zone lymphoma (NMZL), however, remains widely elusive.

METHODS

Comprehensive morphologic, immunophenotypic and cytogenetic studies were carried out on a cohort of NMZL (n = 30) incorporating indolent as well as transformed MZL. In addition, microRNA signatures were generated, employing a quantitative real-time polymerase chain reaction approach. These were then compared to signatures from cases of diffuse large B cell lymphoma (DLBCL) alongside reactive lymph node controls.

RESULTS

While microRNA signatures of low-grade and transformed NMZL did not differ significantly, several microRNAs were differentially expressed between transformed NMZL and DLBCL, hinting at molecularly distinct mechanisms of lymphomagenesis and indicating the biological disparity of transformed NMZL from DLBCL.

CONCLUSION

In the light of the unresolved issue regarding the classification of marginal zone-derived transformed B-cell neoplasms, microRNAs may be a valuable aid in discriminating NMZL from DLBCL.

Recognizing nodal marginal zone lymphoma: recent advances and pitfalls. A systematic review

The diagnosis of nodal marginal zone lymphoma is one of the remaining problem areas in hematopathology. Because no established positive markers exist for this lymphoma, it is frequently a diagnosis of exclusion, making distinction from other low-grade B-cell lymphomas difficult or even impossible. This systematic review summarizes and discusses the current knowledge on nodal marginal zone lymphoma, including clinical features, epidemiology and etiology, histology, and cytogenetic and molecular features. In particular, recent advances in diagnostics and pathogenesis are discussed. New immunohistochemical markers have become available that could be used as positive markers for nodal marginal zone lymphoma. These markers could be used to ensure more homogeneous study groups in future research. Also, recent gene expression studies and studies describing specific gene mutations have provided clues to the pathogenesis of nodal marginal zone lymphoma, suggesting deregulation of the nuclear factor kappa B pathway. Nevertheless, nodal marginal zone lymphoma remains an enigmatic entity, requiring further study to define its pathogenesis to allow an accurate diagnosis and tailored treatment. However, recent data indicate that it is not related to splenic or extranodal lymphoma, and that it is also not related to lymphoplasmacytic lymphoma. Thus, even though the diagnosis is not always easy, it is clearly a separate entity.

The many faces of marginal zone lymphoma

Indolent B-cell lymphomas that are supposed to derive from the marginal zone (marginal zone lymphomas [MZLs]) include 3 specific entities: extranodal marginal zone lymphoma (EMZL) or mucosa-associated lymphatic tissue (MALT) lymphoma, splenic MZL (SMZL), and nodal MZL (NMZL). The clinical and molecular characteristics are different for each entity, with some shared phenotypic and genetic features. EMZL is the most common entity, accounting for approximately 70% of all MZLs. These neoplasms can arise at virtually any extranodal site and are commonly associated with chronic antigenic stimulation either as a result of infection (eg, Helicobacter pylori in the stomach) or autoimmune disease (eg, Sjögren syndrome and salivary glands). Several chromosomal translocations were also identified in EMZL, accounting in the aggregate for approximately one-third of all cases. SMZL accounts for approximately 20% of all MZLs. Patients typically present with an enlarged spleen and involvement of abdominal lymph nodes and BM. Approximately 40%-50% of SMZLs are associated with deletions of chromosome 7q. NMZL is the less common entity, representing approximately 10% of all MZLs. Patients with NMZL, by definition, have lymph node–based disease without involvement of the spleen or extranodal sites. The molecular pathogenesis of NMZL is still unknown.

Nodal marginal zone B cell lymphoma with prominent follicular colonization with deletion of chromosome 13

Nodal marginal zone B cell lymphoma is a rare type of malignant lymphoma and appears to be heterogeneous. Here we report a 60-year-old woman with stage I splenic type of nodal marginal zone B cell lymphoma with prominent follicular colonization. She was treated only by radiation therapy, and remained free of disease on examination for 4 years. The lymph node cells showed an abnormal chromosome of deletion 13, although neither bone marrow cells nor peripheral blood cells demonstrated the same abnormal chromosome. This type of chromosomal abnormality has not been previously reported and may be related to good prognosis in the present case.

Survival of patients with marginal zone lymphoma: analysis of the Surveillance, Epidemiology, and End Results database

BACKGROUND.: Prognostic factors and outcomes in patients with marginal zone lymphoma (MZL) have been studied in small cohort studies, which may not reflect the population at large. METHODS.: Clinical characteristics and survival outcomes of adult patients with MZL who were diagnosed between 1995 and 2009 were evaluated using the Surveillance, Epidemiology, and End Results (SEER) database. The authors generated clinical prognostic models for subtypes of MZL and compared survival during the periods of 1995 through 2000, 2001 through 2004, and 2005 through 2009. RESULTS.: The prognosis was significantly better for patients with mucosa-associated lymphoid tissue (MALT) lymphoma (5-year relative survival rate of 88.7%; P < .0001) compared with those with the splenic MZL (SMLZ)or nodal MZL (NMZL) subtypes (5-year relative survival rates of 79.7% and 76.5%, respectively). There was evidence of improved outcomes in patients with NMZL and MALT lymphomas between 1995 and 2009 (P < .0001), with no difference noted in patients with SMZL (P = .56). Advancing age and the presence of B symptoms had prognostic significance in all MZL subtypes. Male sex and stage of disease were significant only for the NMZL and MALT categories. Survival in patients with MALT lymphomas varied depending on the site of origin, with a worse prognosis noted in those with gastrointestinal and pulmonary locations of origin (5-year incidence rate of lymphoma-related death, 9.5%-14.3%) compared with ocular, cutaneous, and endocrine sites (4.5%-7.8%; P < .0001). CONCLUSIONS.: The survival for patients with SMZL is similar to that for those with NMZL, and unlike the NMZL and MALT subtypes, it has not improved over the past decade. The prognosis of patients with MALT lymphoma varies according to the anatomical site of origin.

Non-MALT marginal zone lymphoma

PURPOSE OF REVIEW

Non-MALT marginal zone lymphoma regroups two subtypes of lymphoma, the splenic marginal zone lymphoma (SMZL) and the nodal marginal zone lymphoma (NMZL). Although they share a common cell of origin from the 'marginal zone', they display different clinical characteristics, reflecting probable biological variations according to the organ.

RECENT FINDINGS

Within the past decade, new data regarding pathogenic mechanisms as well as therapeutic advances have been reported.

SUMMARY

SMZL and NMZL often present with disseminated disease at diagnosis, with specific clinical presentation, SMZL with predominant enlarged splenomegaly and NMZL with disseminated nodal involvement. Diagnosis may be difficult among the small B-cell lymphomas and criteria for diagnosis have been recently improved. The therapeutic approaches comprise splenectomy for SMZL, and immunochemotherapy for both of SMZL and NMZL, but with no consensus about the best treatment, except when associated with hepatitis C virus. This review addresses the current knowledge on the biological findings, clinical features and therapeutic approaches for the individual SMZLs and NMZLs.

Marginal zone lymphomas: factors that affect the final outcome

BACKGROUND

A retrospective review and analysis of 275 patients with marginal zone lymphoma (MZL) was performed to determine prognostic factors. An effort was also made to establish a specific prognostic score for patients with extranodal MZL.

METHODS

Patients were divided into 3 groups according to the type of MZL: extranodal, nodal, and splenic. Factors analyzed included age; gender; presence of B symptoms; Zubrod performance score; clinical stage; serum β(2)-microglobulin, lactate dehydrogenase, albumin, and hemoglobin levels; and presence of autoimmune disorder.

RESULTS

The 5-year overall survival rates of patients with extranodal, nodal, and splenic MZL were 87%, 89%, and 93%, respectively (P = .95). On multivariate analysis, splenic MZL patients had the best prognosis (hazard ratio, 0.18; P = .018). An elevated serum β(2)-microglobulin level (P = .010), B symptoms (P = .021), and male gender (P = .036) were found to be correlated with decreased recurrence-free survival (RFS) on multivariate analysis. Using these 3 variables, a 3-tier prognostic scoring system was created for patients with extranodal MZL: low-risk with no adverse factors, intermediate-risk with 1 adverse factor, and high-risk with ≥ 2 adverse factors. The 5-year RFS rates for the low-risk, intermediate-risk, and high-risk groups were 80%, 71%, and 44%, respectively (P = .01).

CONCLUSIONS

Patients with extranodal and nodal MZL have a similar prognosis, whereas patients with splenic MZL have a better prognosis despite the increased prevalence of negative prognostic indicators. With the use of 3 readily available factors, a prognostic scoring system was identified for patients with extranodal MZL.

Immunoarchitectural patterns in nodal marginal zone B-cell lymphoma: a study of 51 cases

Nodal marginal zone lymphoma (NMZL) represents a rare and heterogeneous group that lacks markers specific for the diagnosis. We evaluated morphologic and immunoarchitectural features of 51 NMZLs, and the following immunostains were performed: CD20, CD21, CD23, CD5, CD3, CD43, CD10, Ki-67, BCL1, BCL2, BCL6, HGAL, and LMO2. Four immunoarchitectural patterns were evident: diffuse (38 [75%]), well-formed nodular/follicular (5 [10%]), interfollicular (7 [14%]), and perifollicular (1 [2%]). Additional features included a monocytoid component (36 [71%]), admixed large cells (20 [39%]), plasma cells (24 [47%]), compartmentalizing stromal sclerosis (13 [25%]), and prominent blood vessel sclerosis (10 [20%]). CD21 highlighted disrupted follicular dendritic cell meshwork in 35 (71%) of 49 cases, and CD43 coexpression was present in 10 (24%) of 42 cases. A panel of germinal center-associated markers was helpful in eliminating cases of diffuse follicle center lymphoma. Our results highlight the histologic and immunoarchitectural spectrum of NMZL and the usefulness of immunohistochemical analysis for CD43, CD23, CD21, BCL6, HGAL, and LMO2 in the diagnosis of NMZL.

Patients with localized primary non-tonsillar oral diffuse large B-cell lymphoma exhibit favorable prognosis despite a non-germinal center B-cell-like phenotype

Diffuse large B-cell lymphomas are detected frequently in the oral cavity. Although tonsillar lymphomas have been rather well characterized, lymphomas originating from non-tonsillar regions, such as the gingiva, palate, and tongue, have not been well studied. We examined the pathology of clinical samples obtained from 21 patients with localized primary non-tonsillar oral diffuse large B-cell lymphoma. Immunohistological examination of CD10, Bcl-6, and MUM1 determined that 17 of 21 (81%) samples exhibited non-germinal center B-cell type, an increased proportion of non-germinal center B-cell type compared with previous reports in samples of tonsillar origin (P<0.05). The four remaining samples exhibited germinal center B-cell type, although one sample expressed MUM1. Follow-up clinical survival data were obtained from the 17 patients over a range from 4 to 173 months (mean 52 months). All patients were treated with chemotherapies, irradiation, or surgical resection. Sixteen patients achieved complete remission and two patients relapsed, but no patient has died of disease. Extranodal diffuse large B-cell lymphomas of non-germinal center B-cell type are generally characterized by poor prognosis, regardless of localized disease. Interestingly, our results indicate that, unlike similar lymphomas of tonsillar origin, localized primary non-tonsillar oral diffuse large B-cell lymphomas exhibit favorable prognosis, suggesting that these lymphomas may be clinicopathologically distinct.

Mucosa-associated lymphoid tissue lymphoma: molecular pathogenesis and clinicopathological significance

Mucosa-associated lymphoid tissue (MALT) lymphoma is a low-grade tumor closely associated with chronic inflammation such as that of Helicobacter pylori gastritis, Sjogren's syndrome, and Hashimoto's thyroiditis. Tumor regression by H. pylori eradication alone is well known in gastric MALT lymphoma, but some tumors occur in the absence of pre-existing chronic inflammation. The understanding of MALT lymphoma biology has significantly improved, and recurrent cytogenetic alterations have been detected. These include the trisomies 3 and 18, and the translocations t(11;18)(q21;q21), t(1;14)(p22;q32), t(14;18)(q32;q21), and t(3;14)(p14.1;q32). At least some of these alterations result in the constitutive activation of the nuclear factor (NF)-kappaB pathway, and may exert anti-apoptotic action. Apoptosis inhibitor 2-MALT lymphoma-associated translocation 1 (API12-MALT1) fusion, resulting from t(11;18)(q21;q21), is specific to, and is the most common in, MALT lymphomas, and its clinicopathological significance has been studied extensively. The focus of the present review is on the recent progress made in elucidating MALT lymphomagenesis and its clinicopathological impact, especially in terms of the effect of API2-MALT1 fusion on this unique tumor.