MALT1 and BCL10 aberrations in MALT lymphomas and their effect on the expression of BCL10 in the tumour cells

Primary MALT lymphoma of the breast: pathological and radiological characteristics

PURPOSE

Primary Mucosa-associated lymphoid tissue (MALT) lymphoma is a rare diagnosis in the breast, and clinical diagnosis based on radiological features is often challenging. This study aimed to evaluate the clinicopathological, and radiological characteristics of the patients diagnosed with primary breast MALT lymphoma.

METHODS

This study examined 18 cases of primary MALT lymphoma of the breast diagnosed at a single tertiary center between January 2002 to December 2020. Medical charts, radiological imaging and original pathology slides were reviewed for each case.

RESULTS

All cases were female (gender assigned at birth) and presented with a palpable mass or an incidental imaging finding. Imaging presentation ranged from mammographic asymmetries, circumscribed masses, and ultrasound masses lacking suspicious features. Seventeen cases were biopsied under ultrasound; one received a diagnostic excision biopsy. Microscopic examination of the breast specimens demonstrated atypical small lymphocyte infiltration with plasmacytoid differentiation and rare lymphoepithelial lesions. Immunohistochemistry was performed in all cases and established the diagnosis. Most patients were treated with radiotherapy, and only three were treated with chemotherapy. The median follow-up period was 4 years and 7.5 months, and all patients were alive at the last follow-up.

CONCLUSION

Primary MALT breast lymphomas are usually indolent and non-systemic, and local radiotherapy may effectively alleviate local symptoms. Radiological findings show overlap with benign morphological features, which can delay the diagnosis of this unusual etiology. Although further studies involving a larger cohort could help establish the clinical and radiological characteristics of primary breast MALT lymphomas, pathology remains the primary method of diagnosis.

TRIAL REGISTRATION NUMBER

University Health Network Ethics Committee (CAPCR/UHN REB number 19-5844), retrospectively registered.

Role of non-Helicobacter pylori gastric Helicobacters in helicobacter pylori-negative gastric mucosa-associated lymphoid tissue lymphoma

Marginal zone lymphomas rank as the third most prevalent form of non-Hodgkin B-cell lymphoma, trailing behind diffuse large B-cell lymphoma and follicular lymphoma. Gastric mucosa-associated lymphoid tissue lymphoma (GML) is a low-grade B-cell neoplasia frequently correlated with Helicobacter pylori (H. pylori)-induced chronic gastritis. On the other hand, a specific subset of individuals diagnosed with GML does not exhibit H. pylori infection. In contrast to its H. pylori-positive counterpart, it was previously believed that H. pylori-negative GML was less likely to respond to antimicrobial therapy. Despite this, surprisingly, in-creasing evidence supports that a considerable proportion of patients with H. pylori-negative GML show complete histopathological remission after bacterial eradication therapy. Nonetheless, the precise mechanisms underlying this treatment responsiveness are not yet fully comprehended. In recent years, there has been growing interest in investigating the role of non-H. pylori gastric helicobacters (NHPHs) in the pathogenesis of H. pylori-negative GML. However, additional research is required to establish the causal relationship between NHPHs and GML. In this minireview, we examined the current understanding and proposed prospects on the involvement of NHPHs in H. pylori-negative GML, as well as their potential response to bacterial eradication therapy.

Management of Extranodal Marginal Zone Lymphoma: Present and Upcoming Perspectives

Simple Summary

Extranodal marginal zone lymphoma distinguishes itself from other indolent lymphomas due to its unique pathophysiology and natural history. This is reflected in its management, where next to traditional treatment strategies such as observation, radiotherapy or chemotherapy, eradication of the causal agent and even surgery represent important aspects of therapy. This review focuses on the particular aspects of this indolent lymphoma that affect management and summarizes the current evidence and different guidelines.

Abstract

Extranodal marginal zone lymphoma (EMZL) encompasses a subgroup of non-Hodgkin lymphomas that often present with localized involvement and may manifest in a diversity of organs and tissues. EMZL pathogenesis is in some cases linked to chronic inflammation/infection, which may impose additional diagnostic and clinical challenges. The most studied and established connection is the presence of Helicobacter pylori in gastric EMZL. Due to its heterogeneity of presentation and intricate pathological features, treatment can be complex, and staging systems are decisive for the choice of therapy. Nevertheless, there is no consensus regarding the most suitable staging system, and recommendations vary among different countries. As a rule of thumb, in limited stages, a local therapy with surgery or radiation is the preferred option, and it is potentially curative. Of note, eradicating the causal agent may be an important step of treatment, especially in gastric EMZL, in which Helicobacter pylori eradication remains the first-line therapy for the majority of patients. In patients with more advanced stages, watch-and-wait is a valuable option, especially amongst those without clear indications for systemic therapy, and it may be carried on for several years. If watch-and-wait is not an option, systemic therapy may be needed. Even though several agents have been tested as monotherapy or in combination in recent years, there is no consensus regarding the first-line therapy, and decisions can vary depending on individual factors, such as age, clinical performance and stage. This review aims to discuss the several aspects of EMZL, including genetic milieu, pathogenesis and staging systems, that may influence the choice of therapy. In addition, we present a summary of evidence of several systemic therapies, compare different recommendations worldwide and discuss future perspectives and novelties in its therapy.

MALT Lymphoma as a Model of Chronic Inflammation-Induced Gastric Tumor Development

Mucosa-associated lymphoid tissue (MALT) lymphoma, or extranodal marginal zone lymphoma of MALT, is an indolent B-cell non-Hodgkin lymphoma linked with preexisting chronic inflammation. The stomach is the most commonly affected organ and the MALT lymphoma pathogenesis is clearly associated with Helicobacter pylori gastroduodenitis. Inflammation induces the lymphoid infiltrates in extranodal sites, where the lymphoma then subsequently develops. Genetic aberrations arise through the release of reactive oxygen species (ROS), H. pylori-induced endonucleases, and other effects. The involvement of nuclear factor kappa B (NF-κB) pathway activation, a critical regulator of pro-inflammatory responses, further highlights the role of inflammation in gastric MALT lymphoma. The NF-κB pathway regulates key elements of normal lymphocyte function, including the transcription of proliferation-promoting and anti-apoptotic genes. Aberrant constitutive activation of NF-κB signaling can lead to autoimmunity and malignancy. NF-κB pathway activation can happen through both the canonical and non-canonical pathways and can be caused by multiple genetic aberrations such as t(11;18)(q12;q21), t(1;14)(p22;q32), and t(14;18)(q32;q21) translocations, chronic inflammation and even directly by H. pylori-associated mechanisms. Gastric MALT lymphoma is considered one of the best models of how inflammation initiates genetic events that lead to oncogenesis, determines tumor biology, dictates clinical behavior and leads to viable therapeutic targets. The purpose of this review is to present gastric MALT lymphoma as an outstanding example of the close pathogenetic link between chronic inflammation and tumor development and to describe how this information can be integrated into daily clinical practice.

Diffuse large B-cell lymphoma: can genomics improve treatment options for a curable cancer?

Gene-expression profiling and next-generation sequencing have defined diffuse large B-cell lymphoma (DLBCL), the most common lymphoma diagnosis, as a heterogeneous group of subentities. Despite ongoing explosions of data illuminating disparate pathogenic mechanisms, however, the five-drug chemoimmunotherapy combination R-CHOP remains the frontline standard treatment. This has not changed in 15 years, since the anti-CD20 monoclonal antibody rituximab was added to the CHOP backbone, which first entered use in the 1970s. At least a third of patients are not cured by R-CHOP, and relapsed or refractory DLBCL is fatal in ∼90%. Targeted small-molecule inhibitors against distinct molecular pathways activated in different subgroups of DLBCL have so far translated poorly into the clinic, justifying the ongoing reliance on R-CHOP and other long-established chemotherapy-driven combinations. New drugs and improved identification of biomarkers in real time, however, show potential to change the situation eventually, despite some recent setbacks. Here, we review established and putative molecular drivers of DLBCL identified through large-scale genomics, highlighting among other things the care that must be taken when differentiating drivers from passengers, which is influenced by the promiscuity of activation-induced cytidine deaminase. Furthermore, we discuss why, despite having so much genomic data available, it has been difficult to move toward personalized medicine for this umbrella disorder and some steps that may be taken to hasten the process.

Novel developments in the pathogenesis and diagnosis of extranodal marginal zone lymphoma

Extranodal marginal zone lymphoma (EMZL), mostly represented by mucosa-associated lymphoid tissue (MALT) type, also referred to as MALT lymphoma, is a clinically heterogeneous entity within the group of low-grade B cell lymphomas that arises in a wide range of different extranodal sites, including the stomach, lung, ocular adnexa, and skin. It represents the third most common non-Hodgkin lymphoma in the Western world, and the median age of occurrence is around 60 years. One characteristic aspect in a subset of EMZL detectable in about 25% of the cases is the presence of specific chromosomal translocations involving the genes MALT1 and BCL10, which lead to activation of the NF-κB signaling pathway. Another unique aspect is that several infectious agents, such as Helicobacter pylori in the case of gastric EMZL, and autoimmune disorders, like Sjögren syndrome, have been implicated in the pathogenesis of this cancer. Recent findings as summarized in this review have further improved our understanding of the complex pathobiology of this disease and have been essential to better define novel treatment strategies. In addition, many of these specific features are currently being implemented for the diagnosis of EMZL.

Molecular pathogenesis of lymphomas of mucosa-associated lymphoid tissue--from (auto)antigen driven selection to the activation of NF-κB signaling

Lymphomas of mucosa-associated lymphoid tissue (MALT) are typically present at sites such as the stomach, lung or urinary tract, where lymphoid tissues scatter in mucosa lamina propria, intra- or sub-epithelial cells. The infection of certain pathogens, such as Helicobacter pylori, Chlamydophila psittaci, Borrelia burgdorferi, hepatitis C virus, or certain autoantigens cause these sites to generate a germinal center called the "acquired lymphoid tissue". The molecular pathogenesis of MALT lymphoma is a multi-step process. Receptor signaling, such as the contact stimulation of B cell receptors and CD4 positive T cells mediated by CD40/CD40-ligand and T helper cell type 2 cytokines like interleukin-4, contributes to tumor cell proliferation. A number of genetic alterations have been identified in MALT lymphoma, and among them are important translocations, such as t(11;18)(q21;q21), t(1;14)(p22;q32), t(14;18)(q32;q21) and t(3;14)(p13;q32). Fusion proteins generated by these translocations share the same NF-κB signaling pathway, which is activated by the caspase activation and recruitment domain containing molecules of the membrane associated guanylate kinase family, B cell lymphoma-10 and MALT1 (CBM) protein complex. They act downstream of cell surface receptors, such as B cell receptors, T cell receptors, B cell activating factors and Toll-like receptors, and participate in the biological process of MALT lymphoma. The discovery of therapeutic drugs that exclusively inhibit the antigen receptor signaling pathway will be beneficial for the treatment of B cell lymphomas in the future.

Clinicopathologic Study of Chromosomal Aberrations in Ocular Adnexal Lymphomas of Korean Patients

Purpose

The incidence and clinical correlation of MALT1 translocation and chromosomal numerical aberrations in Korean patients with ocular adnexal mucosa associated lymphoid tissue (MALT) lymphoma have not yet been reported. We investigated the incidence and clinicopathologic relationship of these chromosomal aberrations in ocular adnexal MALT lymphomas in a Korean population.

Methods

Thirty ocular adnexal MALT lymphomas were investigated for the t(11;18) API2-MALT1, t(14;18) IgH-MALT1 translocations and chromosomes 3 and 18 aneuploidies using fluorescence in situ hybridization. Patient medical records were reviewed retrospectively for information on demographics and clinical characteristics, including treatment response.

Results

The MALT1 gene rearrangement was found in one out of 30 cases. The t(14;18) IgH-MALT1 translocation was demonstrated in only one case (3.3%), and the t(11;18) API2-MALT1 translocation was not found in any of the cases. Trisomy 3 was observed in three ocular adnexal MALT lymphomas (10.0%), and five cases showed trisomy 18 (16.7%). Translocation positive cases also showed trisomy 18. One case of tumor relapse showed trisomy 18 only in the recurrent biopsies. There were no statistically significant correlations between chromosomal aberrations and clinical characteristics and treatment responses.

Conclusions

Translocations involving the MALT1 gene are not common in Korean ocular adnexal MALT lymphomas. The t(14;18) translocation was detected in only one out of 30 cases, and the t(11;18) translocation was not found at all. Furthermore, the chromosomal aberrations found in this study had no prognostic implications.

T(14;18)(q32;q21) involving MALT1 and IGH genes occurs in extranodal diffuse large B-cell lymphomas of the breast and testis

Primary B-cell lymphoma of the testis, breast and thyroid are rare and data concerning cytogenetic aberrations at these extranodal sites are scarce. We examined the presence of extranodal marginal zone lymphoma-associated translocations, t(11;18)(q21;q21), t(1;14)(p22;q32), t(14;18)(q32;q21), t(3;14)(p14.1;q32) and numerical aberrations of chromosomes 1, 3, 12 and 18 by fluorescence in situ hybridization in 6 extranodal marginal zone lymphomas and 24 diffuse large B-cell lymphomas with (n=9) or without (n=15) marginal zone lymphoma components, with primary localizations in the breast (n=15), testis (n=9) and thyroid (n=6). We found t(14;18)(q32;q21), with breakpoints in IGH and MALT1, in one testicular diffuse large B-cell lymphoma and in two diffuse large B-cell lymphomas of the breast. No other translocations, amplifications or deletions involving IGH, BCL-10, BCL-2, MALT1 and IAP2 were detected. Numerical aberrations occurred in 67% of the lymphomas, 67% of extranodal marginal zone lymphomas, 56% of diffuse large B-cell lymphomas with marginal zone lymphoma components and in 73% of 'de novo' diffuse large B-cell lymphomas. These included 78% of testis, 67% of thyroid and 60% of breast lymphomas, and included mainly trisomy 18 (n=16), trisomy 3 (n=8) and trisomy 1 (n=3). One testicular diffuse large B-cell lymphoma harbored both t(14;18)(q32;q21) and trisomy 3. Our results indicate that at least a few cases of diffuse large B-cell lymphoma of the testis and the breast belong to the spectrum of extranodal marginal zone lymphoma.

Gastrointestinal B-cell lymphomas: From understanding B-cell physiology to classification and molecular pathology

The gut is the most common extranodal site where lymphomas arise. Although all histological lymphoma types may develop in the gut, small and large B-cell lymphomas predominate. The sometimes unexpected finding of a lymphoid lesion in an endoscopic biopsy of the gut may challenge both the clinician (who is not always familiar with lymphoma pathogenesis) and the pathologist (who will often be hampered in his/her diagnostic skill by the limited amount of available tissue). Moreover, the past 2 decades have spawned an avalanche of new data that encompasses both the function of the reactive B-cell as well as the pathogenic pathways that lead to its neoplastic counterpart, the B-cell lymphoma. Therefore, this review aims to offer clinicians an overview of B-cell lymphomas in the gut, and their pertinent molecular features that have led to new insights regarding lymphomagenesis. It addresses the question as how to incorporate all presently available information on normal and neoplastic B-cell differentiation, and how this knowledge can be applied in daily clinical practice (e.g., diagnostic tools, prognostic biomarkers or therapeutic targets) to optimalise the managment of this heterogeneous group of neoplasms.

Thymic mucosa-associated lymphoid tissue lymphoma in an adolescent girl

Mucosa-associated lymphoid tissue (MALT) lymphoma is very rare in children. We report the first case of pediatric thymic MALT lymphoma in an adolescent Asian girl. She presented with chest pain, dyspnea, and low-grade fever. A large anterior mediastinal mass was biopsied that confirmed the diagnosis of MALT lymphoma with trisomy 18. The patient had secondary immunodeficiency with low NK cell count and high IgA and IgG levels. Because of the advanced stage and the presence of trisomy 18, she was treated with cyclophosphamide, vincristine, prednisone, and rituximab, followed by involved-field radiotherapy. She is currently undergoing maintenance therapy with rituximab and remains in complete remission at 13 months from diagnosis. Thymic MALT lymphoma should be suspected in any Asian child with a cystic thymic mass and autoimmune disease or hyperglobinemia. Because of the slow proliferation rate of this type of lymphoma, a long-term follow-up is needed.

Analysis of microsatellite instability in gastric mucosa-associated lymphoid tissue lymphoma

In Helicobacter pylori gastritis, constant antigenic stimulation triggers a sustained B-cell proliferation. Errors made during this continuous DNA replication are supposed to be corrected by the DNA mismatch repair mechanism. Failure of this mismatch repair mechanism has been described in hereditary non-polyposis colorectal cancer (HNPCC) and results in a replication error phenotype. Inherent to their instability during replication, microsatellites are the best markers of this replication error phenotype. We aimed to evaluate the role of defects in the DNA mismatch repair (MMR) mechanism and microsatellite instability (MSI) in relation to the most frequent genetic anomaly, translocation t(11;18)(q21;q21), in gastric mucosa-associated lymphoid tissue (MALT) lymphoma. Therefore, we examined 10 microsatellite loci (BAT25, BAT26, D5S346, D17S250, D2S123, TGFB, BAT40, D18S58, D17S787 and D18S69) for instability in 28 patients with MALT lymphomas. In addition, these tumors were also immunostained for MLH1, MSH2, MSH6 and PMS2, as well as screened for the presence of t(11;18)(q21;q21) by real-time polymerase chain reaction (RT-PCR). We found MSI in 5/28 (18%) lymphomas, with MSI occurring in both t(11;18)(q21;q21)-positive and -negative tumors. One tumor displayed high levels of instability, and, remarkably, this was the only case displaying features of a diffuse large B-cell lymphoma. All microsatellite unstable lymphomas showed a loss of MSH6 expression. In conclusion, our data suggest that a MMR-defect may be involved in the development of gastric MALT lymphomas, and that a defect of MSH6 might be associated with those MSI-driven gastric lymphomas.

T(11;18)(q21;q21)-positive gastrointestinal MALT lymphomas are heterogeneous with respect to the VH gene mutation status

AIM: To investigate how t(11;18)(q21;q21)-positive gastrointestinal MALT lymphomas relate to other marginal zone lymphomas with respect to the somatic mutation pattern of the V_H genes and the expression of the marker CD27.

METHODS: The V_H gene of 7 t(11;18)(q21;q21)-positive gastrointestinal MALT lymphomas was amplified by PCR using family specific V_H primers and a consensus J_H primer. PCR products were sequenced and mutation analysis of the CDR and the FR regions was performed. All cases were immunostained for CD27.

RESULTS: One case showed unmutated V_H genes while the others showed mutated V_H genes with mutation frequencies ranging from 1.3 to 14.7% and with evidence of antigen selection in 2 cases. These data suggest that the translocation t(11;18)(q21;q21) can target either B-cells at different stages of differentiation or naive B-cells that retain the capacity to differentiate upon antigen stimulation. All cases but one displayed weak to strong CD27 expression which did not correlate with the V_H gene mutation status.

CONCLUSION: t(11;18)(q21;q21)-positive gastrointestinal MALT lymphomas are heterogeneous with respect to the V_H mutation status and CD27 is not a marker of somatically mutated B-cells.

[Systemic mastocytosis--definition of an internal disease]

Systemic mastocytosis comprises disorders characterized by an accumulation of genetically altered mast cells in all organs and tissues due to an increased proliferation rate and reduced apoptosis of those pathologic mast cells. Release of their mediators can effectively influence organ function and can lead to systemic effects without inducing traces in routinely used laboratory parameters or imaging methods. In most cases, little invasive investigations allow diagnosing the disease and, hence, an appropriate therapy consisting of a basic medication with antihistamine and mast cell membrane-stabilizing compounds that should be supplemented, if required, by a medication adapted to individual symptoms, can be initiated. Because of the probably high prevalence of the disorder, systemic mastocytosis should be considered as a differential diagnosis in particular in the case of chronic gastrointestinal complaints such as abdominal pain/discomfort possibly associated with diarrhea, at an early stage.

The basis and rational use of molecular genetic testing in mature B-cell lymphomas

An increasing number of neoplasms are associated with variably specific genetic abnormalities. This is best exemplified by hematological malignancies, in which there is a growing list of entities that are defined by their genetic lesion(s); this is not (yet) the case in mature B-cell lymphomas. However, enhanced insights into the pathogenesis of this large and diverse group of lymphomas have emerged with the ongoing unraveling of a plethora of fascinating genetic abnormalities. The purpose of this review is to synthesize well-recognized data and nascent discoveries in our understanding of the genetic basis of a spectrum of mature B-cell lymphomas, and how this may be applied to contemporary clinical practice. Despite the explosion of new and exciting knowledge in this arena, with the potential for enhanced diagnostic and prognostic strategies, it is essential to remain cognizant of the limitations (and complexity) of genetic investigations, so that assays can be developed and used both judiciously and rationally.

Ocular adnexal lymphomas: a review

Ocular adnexal lymphomas comprise 1% to 2% of all non-Hodgkin lymphomas and about 8% of extranodal lymphomas. They are a heterogeneous group of malignancies, the majority of which are primary extranodal lymphoma with most (up to 80%) of the marginal zone of mucosa associated lymphoid tissue type (MALT lymphoma). This review will encompass the incidence, histology, immunophenotyping, recent advances in molecular and cytogenetics, clinical features including outcome, and prognostic factors. The association with Chlamydia psittaci and the very recently recognized occurrence in the context of IgG4-related sclerosing disease will be discussed. Finally, traditional (surgery, radiotherapy, chemotherapy) and newer forms of therapy (immunotherapy and radioimmunotherapy) will be reviewed.

Gastric MALT lymphoma: a model of chronic inflammation-induced tumor development

Mucosa-associated lymphoid tissue (MALT) lymphoma, or extranodal marginal zone lymphoma of MALT, is an indolent B-cell non-Hodgkin lymphoma arising in lymphoid infiltrates that are induced by chronic inflammation in extranodal sites. The stomach is the most commonly affected organ, in which MALT lymphoma pathogenesis is clearly associated with Helicobacter pylori gastroduodenitis. Gastric MALT lymphoma has attracted attention because of the involvement of genetic aberrations in the nuclear factor kappaB (NFkappaB) pathway, one of the most investigated pathways in the fields of immunology and oncology. This Review presents gastric MALT lymphoma as an outstanding example of the close pathogenetic link between chronic inflammation and tumor development, and describes how this information can be integrated into daily clinical practice. Gastric MALT lymphoma is considered one of the best models of how genetic events lead to oncogenesis, determine tumor biology, dictate clinical behavior and represent viable therapeutic targets. Moreover, in view of the association of gastric MALT lymphoma with dysregulation of the NFkappaB pathway, this signaling pathway will be discussed in depth in both normal and pathological conditions, highlighting strategies to identify new therapeutic targets in this lymphoma.

Comparative expressed sequence hybridization studies of t(11;18)(q21;q21)-positive and -negative gastric MALT lymphomas reveal both unique and overlapping gene programs

Among the genetic abnormalities reported to occur in MALT lymphomas, the translocation t(11;18)(q21;q21) is of particular interest because it is exclusively documented in MALT lymphomas, mainly with gastrointestinal location. It results in the creation of a fusion protein API2-MALT1 that activates the transcription factor NF-kappaB through enhanced IKK gamma polyubiquitination. Here, we apply the recently developed molecular technique termed comparative expressed sequence hybridization to identify differentially expressed chromosomal regions related to the pathogenesis of gastric MALT lymphomas. By comparing t(11;18)(q21;q21)-positive gastric MALT lymphomas to their t(11;18)(q21;q21)-negative counterparts, we found that the location of the MALT1 break point determines a difference in expression pattern within the t(11;18)(q21;q21)-positive group. Moreover, we could define a gastric MALT lymphoma signature, which most likely comprises the regions and genes with significance in the development of MALT lymphomas, by comparing both t(11;18)(q21;q21)-positive and -negative MALT lymphomas to normal lymphoid tissue. Finally, a significant imprint of the marginal zone signature, established by comparing microdissected, splenic B follicles with and without marginal zone, was evident in the expression profile of MALT lymphoma, further supporting a marginal zone origin for this type of B-cell non-Hodgkin's lymphoma.

Chronic inflammatory disease, lymphoid tissue neogenesis and extranodal marginal zone B-cell lymphomas

Chronic autoimmune or pathogen-induced immune reactions resulting in lymphoid neogenesis are associated with development of malignant lymphomas, mostly extranodal marginal zone B-cell lymphomas (MZBCLs). In this review we address (i) chemokines and adhesion molecules involved in lymphoid neogenesis; (ii) the autoimmune diseases and pathogens which are associated with development of B-cell lymphomas; (iii) the molecular mechanisms involved in the initiation and progression of MZBCL; and (iv) 'potential' mouse models for MZBCL.

Primary mucosa-associated lymphoid tissue lymphoma of the gallbladder: report of a case harboring API2/MALT1 gene fusion

The genetic alterations underlying extranodal marginal zone B-cell lymphomas of mucosa-associated lymphoid tissue type are heterogeneous and show variation according to the tumor site. Here, we report a case of mucosa-associated lymphoid tissue lymphoma of the gallbladder with genetic characterization. This lymphoma, diagnosed in a 75-year-old woman who underwent cholecystectomy for suspected acute cholecystitis, presented as diffuse thickening of the gallbladder wall. The morphology was typical of mucosa-associated lymphoid tissue lymphoma, and by immunophenotype, the tumor cells were CD20+ CD5- CD10- CD23- CD43- BCL6- BCL2+ IgM+ IgD- lambda+, with moderate nuclear expression of BCL10. Interphase fluorescence in situ hybridization analysis on paraffin sections, using a fusion probe for API2/MALT1, demonstrated 2 fusion signals in most nuclei, bringing the first documentation of a t(11;18)(q21;q21) in this exceptional primary disease location.

Germline variations of the MALT1 gene as risk factors in the development of primary gastric B-cell lymphoma

Gastric mucosa-associated lymphoid tissue (MALT) lymphoma is a histologically distinct tumour derived from MALT acquired as a result of Helicobacter pylori infection. The genetic susceptibility to develop primary gastric B-cell lymphoma in patients with chronic H. pylori infection is unknown. MALT1 plays a key role in malignant B-cell transformation and lymphoma progression. Thus, we investigated germline variations of MALT1 as risk factors for gastric lymphoma in a large cohort from a European multicentre study and in total 214 lymphoma patients, 593 H. pylori infected controls and 348 healthy blood donors were genotyped for four single nucleotide polymorphisms (SNPs) covering the MALT1 locus by Taqman technology. Haplotype and single marker analyses were conducted for association testing in a case-control setting. A distinct haplotype was identified that showed a trend towards protection from high-grade and low-grade lymphomas. In single marker analysis individuals homozygous for the rare allele G of SNP3 (rs12969413) were significantly protected only from gastric high-grade lymphoma compared with controls (p=0.002, odds ratio (OR): 0.2, Wald 95% confidence interval (CI): 0.1<OR<0.6). This association could not be confirmed in a second independent cohort of high-grade lymphoma patients from the Lymph node registry in Kiel (p=0.531, OR: 0.8, Wald 95% CI: 0.4<OR<1.5). Due to the fact that SNPs 2, 3 and 4 are arranged in one LD block exhibiting nearly complete linkage disequilibrium it is rather unlikely that germline variations of MALT1 might be involved in the pathogenesis of gastric lymphoma. This is the first genetic association study that investigated polymorphisms of MALT1 as genetic risk factors in the development of primary gastric lymphoma.

Ophthalmic lymphoma: epidemiology and pathogenesis

With a lifetime risk of 1% and 700 new cases per year, Non-Hodgkin lymphoma (NHL) is the seventh most frequent type of cancer in Denmark. The incidence of NHL has increased considerably in Western countries over the last decades; consequently, NHL is an increasing clinical problem. Ophthalmic lymphoma, (lymphoma localized in the ocular region, i.e. eyelid, conjunctiva, lacrimal sac, lacrimal gland, orbit, or intraocularly) is relatively uncommon, accounting for 5%-10% of all extranodal lymphomas. It is, however, the most common orbital malignancy. The purpose of this thesis was to review specimens from all Danish patients with a diagnosis of ophthalmic lymphoma during the period 1980-2005, in order to determine the distribution of lymphoma subtypes, and the incidence- and time trends in incidence for ophthalmic lymphoma. Furthermore, an extended analysis of the most frequent subtype, extranodal marginal zone lymphoma (MALT lymphoma), was done to analyse clinical factors and cytogenetic changes with influence on prognosis. A total of 228 Danish patients with a biopsy-reviewed verified diagnosis of ocular adnexal-, orbital-, or intraocular lymphoma were identified. We found that more than 50% of orbital- and ocular adnexal lymphomas were of the MALT lymphoma subtype, whereas diffuse large B-cell lymphoma (DLBCL) predominated intraocularly (Sjo et al. 2008a). Furthermore, lymphoma arising in the lacrimal sac was surprisingly predominantly DLBCL (Sjo et al. 2006). Incidence rates were highly dependent on patient age. There was an increase in incidence rates for the whole population from 1980 to 2005, corresponding to an annual average increase of 3.4% (Sjo et al. 2008a). MALT lymphoma arising in the ocular region was found in 116 patients (Sjo et al. 2008b). One third of patients had a relapse or progression of disease after initial therapy and relapses were frequently found at extra-ocular sites. Overall survival, however, was not significantly poorer for patients with relapse. Furthermore, we found that the frequency of translocations involving the MALT1- and IGH-gene loci is low in ocular region MALT lymphoma (2 of 42, 5%), but may predict increased risk of relapse (Sjo et al. 2008b). In conclusion the incidence of ophthalmic lymphoma is increasing at a high rate in Denmark. Ophthalmic lymphoma consists primarily of MALT lymphoma. The molecular pathogenesis of MALT lymphoma arising in the ocular region rarely involves translocations in the MALT1- and IGH-gene loci.

[Chromosomal abnormalities and Waldenström macroglobulinemia]

Waldenström macroglobulinemia (WM) is now defined as an uncommon lymphoplasmocytic proliferation associated with an immunoglobulin M peak. The associated chromosomal abnormalities are not specific to the disease, and changes in the diagnostic criteria and techniques used as well as low-level abnormal cell proliferation made their analysis difficult. A literature review however, shows that if specific abnormalities were not recognized until now, it is the frequency of some chromosomal abnormalities (for instance partial deletion of the long arm of chromosome 6 and trisomy 4) that distinguishes WM from other chronic malignant B-cell proliferations. The data collected in the present review show directions for future research which will benefit from use of more recent techniques such as fluorescent in situ hybridization, comparative genomic hybridization and expression microarrays.

Extranodal lymphoma

Lymphomas arising in extranodal sites are intriguing. The types of lymphomas encountered vary widely from one extranodal site to another. For many types of extranodal lymphomas, there are distinctive clinicopathologic features, sometimes including association with an underlying immunodeficiency syndrome, autoimmune disease, infection, or other immunologic disorder, or a predilection to affect patients of certain ethnic origins. Presented below is a review of lymphomas that are encountered most often in extranodal sites.

Lymphoma of the ocular adnexa: A study of 353 cases

We studied the cases of 353 patients with lymphoma involving the ocular adnexa diagnosed at the Massachusetts General Hospital between 1974 and 2005. The patients included 153 males and 200 females, aged 7 to 95 years, with a mean age of 64 years. In 277 cases, there was no known history of lymphoma. Seventy-six patients had a history of lymphoma, with the ocular adnexa being involved at relapse or with progression of the previously diagnosed lymphoma. The patients had marginal zone lymphoma (182 cases), follicular lymphoma (80 cases), mantle cell lymphoma (18 cases), small lymphocytic lymphoma/chronic lymphocytic leukemia (13 cases), lymphoplasmacytic lymphoma (4 cases), splenic marginal zone lymphoma (2 cases), low-grade B cell, not subclassified (19 cases), precursor B lymphoblastic lymphoma (3 cases), diffuse large B-cell lymphoma (26 cases), and 1 case each of high-grade B-cell lymphoma, not subclassified, peripheral T-cell lymphoma, unspecified type, extranodal NK/T-cell lymphoma, nasal type, and Hodgkin lymphoma, nodular sclerosis type. Almost all marginal zone lymphoma patients (168 of 182, 92%) had primary ocular adnexal lymphoma. Fourteen marginal zone lymphoma patients (8%) had a prior history of lymphoma, usually arising in another extranodal site. Twenty-five of 80 (31%) follicular lymphoma patients had a prior history of lymphoma, usually arising in lymph nodes. Patients with mantle cell lymphoma, chronic lymphocytic leukemia, lymphoplasmacytic lymphoma, and splenic marginal zone lymphoma almost always had a prior history of lymphoma or were known to have widespread disease at the time of diagnosis of ocular adnexal lymphoma. A subset of the diffuse large B-cell lymphomas were associated with large destructive masses involving adjacent structures such as paranasal sinuses, raising the possibility that they may have arisen from one of the adjacent structures and involved the ocular adnexa by direct extension. The relatively high proportion of low-grade lymphoma, not subclassified, highlights the difficulty that may arise in distinguishing different types of low-grade lymphoma, particularly when biopsies are small and artifactually distorted. Ocular adnexal lymphoma is primarily a disease of older adults, with a slight female preponderance. Most lymphomas are low-grade B-cell lymphomas, with marginal zone lymphoma being by far the most common type. Marginal zone lymphoma typically involves the ocular adnexa primarily, whereas other types of low-grade B-cell lymphoma often involve the ocular adnexa secondarily. High-grade B-cell lymphomas only occasionally involve the ocular adnexa, and T-cell lymphoma, NK-cell lymphoma, and Hodgkin lymphoma are only rarely encountered in this site.

The pathogenesis of MALT lymphomas: where do we stand?

Mucosa-associated lymphoid tissue (MALT) lymphoma is a heterogeneous form of a B-cell non-Hodgkin's lymphoma with extranodal location. The gastrointestinal tract is the most common site of disease, but involvement of multiple other organ systems has been documented. Four translocations, t(11;18)(q21;q21), t(1;14)(p22;q32), t(14;18)(q32;q21) and t(3;14)(p13;q32), are specifically associated with MALT lymphoma. Remarkably, the genes targeted by at least three of these translocations are involved in one and the same pathway, leading to the activation of nuclear factor-kappaB (NF-kappaB). This review presents MALT lymphoma as a model of how sustained inflammation increases the risk of genotoxic insults and how these genetic events initiate oncogenesis.

MALT1 gene rearrangements and NF-kappaB activation involving p65 and p50 are absent or rare in primary MALT lymphomas of the breast

Mucosa associated lymphoid tissue (MALT) lymphomas arising in the breast are uncommon and few cases have been assessed for MALT lymphoma-associated translocations, BCL-10 expression, or NF-kappaB activation. In this study, we analyzed eight cases of primary breast MALT lymphoma. We also included 14 cases of primary breast diffuse large B-cell lymphoma since some of these may represent transformation of MALT lymphoma, known to occur at extra-mammary MALT sites. All cases were assessed for MALT1 gene rearrangements by fluorescence in situ hybridization (FISH). Using immunohistochemical methods, all cases were assessed for BCL-10, and subsets were assessed for NF-kappaB p65 and p50. None of the cases had MALT1 gene rearrangements by FISH. Of eight MALT lymphomas, BCL-10 was positive in seven (88%), with moderate nuclear and cytoplasmic staining in six, and a weak cytoplasmic staining in one. NF-kappaB p65 (n=8) and p50 (n=5) were negative or showed only cytoplasmic staining (ie inactivated) in all cases. Of 14 diffuse large B-cell lymphoma cases, BCL-10 was positive in 12 (87%), with weak-to-moderate cytoplasmic staining in 10, weak cytoplasmic and focally nuclear staining in one, and a moderate-to-strong nuclear and cytoplasmic staining in one. NF-kappaB p65 (n=11) showed cytoplasmic staining in all cases, whereas p50 (n=8) showed nuclear positivity (ie activated) in two (25%) cases. We conclude that MALT1 gene rearrangements are absent or rare in primary breast MALT lymphoma and diffuse large B-cell lymphoma. In MALT lymphomas, the moderate BCL-10 nuclear expression in six neoplasms is inconsistent with the FISH results, suggesting that BCL-10 immunostaining overestimates the frequency of MALT1 gene rearrangements. We also could not demonstrate NF-kappaB activation using nuclear staining for p65 and p50. In contrast, breast diffuse large B-cell lymphomas are heterogeneous. Weak cytoplasmic BCL-10 staining in most cases and evidence of NF-kappaB p50 activation in a subset differs from breast MALT lymphomas.

Nuclear BCL-10 expression is common in lymphoplasmacytic lymphoma/Waldenström macroglobulinemia and does not correlate with p65 NF-kappaB activation

B-cell lymphoma 10 (BCL-10) is expressed in the cytoplasm of normal germinal center and marginal zone B-cells and is involved in lymphocyte development and activation. Aberrant nuclear expression of BCL-10 occurs in a subset of extranodal marginal zone B-cell lymphomas (MALT lymphomas), primarily those with the t(1;14)(p22;q32) or t(11;18)(q21;q21). Little is known about BCL-10 expression in lymphoplasmacytic lymphoma/Waldenström macroglobulinemia (LPL/WM). We assessed for BCL-10 in 51 bone marrow (BM) specimens involved by LPL/WM using immunohistochemical methods. All patients had monoclonal IgM in serum. Extent of BM involvement was assessed using PAX-5/BSAP and CD20 immunostains and the pattern and percentage of B-cells positive for BCL-10 was determined. The p65 subunit of nuclear factor-kappa B (NF-kappaB), a molecule downstream of BCL-10, was also assessed immunohistochemically. Nuclear BCL-10 staining was present in 28/51 (55%) specimens. BCL-10 expression correlated with greater extent of BM involvement (P=0.001), but did not correlate with serum IgM paraprotein levels, type of immunoglobulin light chain, or clinical variables. Nuclear expression of the p65 subunit of NF-kappaB was detected in 17/50 (34%) specimens, suggesting that NF-kappaB is active in a subset of LPL/WM. p65 NF-kappaB activation did not correlate with nuclear BCL-10 immunostaining. Cytogenetic analysis in 29 cases showed no evidence of the t(1;14) or t(11;18). These results indicate that nuclear BCL-10 expression is common in LPL/WM and does not correlate with MALT lymphoma-associated translocations or p65 NF-kappaB nuclear staining.

Forkhead box protein P1 expression in mucosa-associated lymphoid tissue lymphomas predicts poor prognosis and transformation to diffuse large B-cell lymphoma

PURPOSE

Gene expression profiling studies have reported upregulated mRNA expression of forkhead box protein P1 (FOXP1) in response to normal B-cell activation and high expression in a poor prognosis subtype of diffuse large B-cell lymphoma (DLBCL). Recently, it was also found that FOXP1 rearrangements and expression of its protein occur in mucosa-associated lymphoid tissue (MALT) lymphomas. In this study, we investigated FOXP1 expression in its relationship to morphology, genetic features, and prognosis in a series of 70 MALT lymphomas.

PATIENTS AND METHODS

All samples were morphologically reviewed and stained for FOXP1. Presence of structural and/or numeric aberrations of the FOXP1, BCL10, and MALT1 genes was investigated. For all patients, a complete clinical data set was collected.

RESULTS

We detected nuclear expression of FOXP1 in 20 of the 70 MALT lymphomas (nine of them featuring structural or numeric aberrations of the FOXP1 locus). FOXP1 positivity was confined to MALT lymphomas with poor clinical outcome (with impact of FOXP1 expression on relapse rate and disease-free survival). It was also found that MALT lymphomas with strong FOXP1 expression are at risk of transforming into an aggressive DLBCL of nongerminal center phenotype if they feature, in addition, a polymorphic histology and the presence of trisomy 3 and 18.

CONCLUSION

The data presented show that FOXP1 expression is an independent prognostic factor in MALT lymphomas. The data also support the hypothesis that a subgroup of nongerminal center DLBCLs (those marked by FOXP1 expression and trisomy 3 and 18) might represent a large-cell variant of MALT lymphomas.