The incidence and anatomic site specificity of chromosomal translocations in primary extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma) in North America

How I diagnose B-cell lymphoproliferative disorders with plasmacytic differentiation

OBJECTIVES

B-cell lymphomas with plasmacytic differentiation is a broad category that includes small and large B-cell lymphomas. In this review, we focus on the small B-cell lymphomas, which include lymphoplasmacytic lymphoma and marginal zone lymphomas, among others. We aimed to review the diagnostic criteria of each entity and the features that distinguish them from each other.

METHODS

We discuss the clinical presentation, morphology, immunophenotype, molecular features, and potential pitfalls of diagnosing B-cell lymphomas with plasmacytic differentiation and provide 2 illustrative cases.

RESULTS

In some instances, small B-cell lymphomas with plasmacytic differentiation, particularly lymphoplasmacytic lymphoma and certain marginal zone lymphomas, have overlapping morphologic and immunophenotypic features. As a result, differentiating them may be difficult.

CONCLUSIONS

In cases where classification is challenging, integration with clinical, radiologic, and laboratory findings may be helpful in arriving at a specific diagnosis. Instances remain, however, in which classification is difficult.

A case of pulmonary mucosa-associated lymphoid tissue lymphoma diagnosed by detecting t(11;18)(q21;q21) in bronchial lavage fluid

A 76-year-old woman was diagnosed with mucosa-associated lymphoid tissue (MALT) lymphoma by upper gastrointestinal endoscopy. She underwent further investigation for concomitant bilateral pleural effusions and right pulmonary consolidation. MALT lymphoma with the t(11; 18)(q21; q21) translocation and API2-MALT1 were detected in pleural fluid. Lymphoma was not histopathologically diagnosed by lung biopsies, but the same translocation was identified in bronchial lavage. MALT lymphoma is often difficult to diagnose by bronchoscopy because of only mild dysplasia. However, present report on using chromosomal translocation analysis from bronchial lavage indicates that such testing may serve as a useful diagnostic adjunct in MALT lymphoma with lung involvement.

A Case of Persistent Lung Masses After Treatment of Hodgkin Lymphoma

CASE PRESENTATION

The patient is a 49-year-old woman who had never used tobacco with a history of relapsing polychondritis and episcleritis. She sought treatment at our clinic for evaluation of multiple lung masses. She originally received a diagnosis by chest radiography performed to rule out sarcoidosis as the cause of episcleritis showing an abnormal findings. She had no contributory surgical, family, or social history. The autoimmune markers were notable for positive rheumatoid factor (153 IU/mL) and elevated erythrocyte sedimentation rate (97 mm/h) and C-reactive protein (65.5 mg/L). Pertinent studies with negative results included antineutrophilic cytoplasmic antibody, antinuclear antibody, cyclic citrullinated peptide antibody, Sjogren syndrome-related antigen A, and Sjogren syndrome-related antigen B tests.

Long-term monitoring of gastric mucosa-associated lymphoid tissue lymphoma in patients with extra copies of the MALT1 gene

The objective of this study was to clarify the long-term prognosis of patients with gastric mucosa-associated lymphoid tissue (MALT) lymphoma with additional copies of MALT1. In this multicenter retrospective study, we enrolled 145 patients with gastric MALT lymphoma who underwent fluorescence in situ hybridization (FISH) analysis to detect t(11;18) translocation. The patient cohort was divided into three groups: Group A (n = 87), comprising individuals devoid of the t(11;18) translocation or extra MALT1 copies; Group B (n = 27), encompassing patients characterized by the presence of the t(11;18) translocation; and Group C (n = 31), including patients with extra MALT1 copies. The clinical outcomes in each cohort were collected. Over the course of a mean follow-up of 8.5 ± 4.2 years, one patient died of progressive MALT lymphoma, while 15 patients died due to etiologies unrelated to lymphoma. The progression or relapse of MALT lymphoma was observed in 11 patients: three in Group A, two in Group B, and six in Group C. In Groups A, B, and C, the 10-year overall survival rates were 82.5%, 93.8%, and 86.4%, respectively, and the 10-year event-free survival rates were 96.1%, 96.0%, and 82.9%, respectively. The event-free survival rate in Group C was significantly lower than that in Group A. However, no differences were observed in the 10-year event-free survival rates among individuals limited to stage I or II1 disease (equivalent to excluding patients with stage IV disease in this study, as there were no patients with stage II2), with rates of 98.6%, 95.8%, and 92.3% for Groups A, B, and C, respectively. In conclusion, the presence of extra copies of MALT1 was identified as an inferior prognostic determinant of event-free survival. Consequently, trisomy/tetrasomy 18 may serve as an indicator of progression and refractoriness to therapeutic intervention in patients with gastric MALT lymphoma, particularly stage IV gastric MALT lymphoma.

Cytogenomics of B-cell non-Hodgkin lymphomas: The "old" meets the "new"

For the routine diagnosis of haematological neoplasms an integrative approach is used considering the morphology, and the immunophenotypic, and molecular features of the tumor sample, along with clinical information. The identification and characterization of recurrent chromosomal aberrations mainly detected by conventional and molecular cytogenetics in the tumor cells has a major impact on the classification of lymphoid neoplasms. Some of the B-cell non-Hodgkin lymphomas are characterized by particular chromosomal aberrations, highlighting the relevance of conventional and molecular cytogenetic studies in their diagnosis and prognosis. In the current genomics era, next generation sequencing provides relevant information as the mutational profiles of haematological malignancies, improving their classification and also the clinical management of the patients. In addition, other new technologies have emerged recently, such as the optical genome mapping, which can overcome some of the limitations of conventional and molecular cytogenetics and may become more widely used in the cytogenetic laboratories in the upcoming years. Moreover, epigenetic alterations may complement genetic changes for a deeper understanding of the pathogenesis underlying B-cell neoplasms and a more precise risk-based patient stratification. Overall, here we describe the current state of the genomic data integrating chromosomal rearrangements, copy number alterations, and somatic variants, as well as a succinct overview of epigenomic changes, which altogether constitute a comprehensive diagnostic approach in B-cell non-Hodgkin lymphomas.

Follicular lymphoma and marginal zone lymphoma: how many diseases?

Follicular lymphoma (FL) and marginal zone lymphoma (MZL) are indolent mature B-cell neoplasms with variable clinical presentation and distinct histopathologic features. Recent advances in the biology and molecular characteristics of these lymphomas have further expanded our understanding of the heterogeneous nature of these lymphomas, with increasing recognition of specific disease entities within the broader categories of FL and MZL. Here, we discuss the conclusions of the 2022 International Consensus Classification of Mature Lymphoid Neoplasms (2022 ICC) dealing with FL, and review differences with the proposed WHO 5th Edition classification. We review issues related to grading and alternative forms of FL especially those lacking the genetic hallmark of FL, the t(14;18) chromosomal alteration. Among them, t(14;18)-negative CD23⁺ follicle center lymphoma has been proposed by the 2022 ICC as a provisional entity. Other follicle center-derived lymphomas such as pediatric-type follicular lymphoma, testicular follicular lymphoma, primary cutaneous follicle center lymphoma, and large B-cell lymphoma with IRF4 rearrangement are considered distinct entities separate from conventional FL. Importantly, large B-cell lymphoma with IRF4 rearrangement introduced as a provisional entity in the WHO 2017 is upgraded to a definite entity in the 2022 ICC. We also discuss diagnostic strategies for recognition of MZLs including splenic MZL, extranodal MZL (MALT lymphoma), and primary nodal MZL. The importance of molecular studies in the distinction among marginal zone lymphoma subtypes is emphasized, as well as their value in the differential diagnosis with other B-cell lymphomas.

Pulmonary Nodular Lymphoid Hyperplasia Evaluated with Bronchoalveolar Lavage Fluid Findings: A Case Report and Review of the Literature on Japanese Patients

Pulmonary nodular lymphoid hyperplasia (PNLH) is a very rare disease, and it is difficult to diagnose PNLH and distinguish it from mucosa-associated lymphoid tissue (MALT) lymphoma. In addition, information on bronchoalveolar lavage fluid (BALF) analyses is lacking. We herein report a 36-year-old Japanese woman diagnosed with PLNH by a surgical biopsy and analysis of BALF. The BALF showed an increase in B-cell marker-positive lymphocytes, normal patterns of B-cell clonality, mucosa-associated lymphoid tissue 1 gene, and immunoglobulin heavy chain at 14q32 translocations. We also reviewed Japanese cases of PNLH described in Japanese or English to explore the characteristics of such cases.

Pulmonary mucosa-associated lymphoid tissue (MALT) lymphoma associated with coeliac disease

Pulmonary mucosa-associated lymphoid tissue (pMALT) lymphomas are rare, representing <1% of lung malignancies. An association between pMALT and autoimmune conditions has been described, but there is a paucity of documented cases linked to coeliac disease. We present the case of a patient with a history of coeliac disease who presented with weight loss but no respiratory symptoms. CT revealed diffuse endobronchial opacities with associated bronchial dilation and pulmonary nodules. Bronchoscopy confirmed widespread polypoid endobronchial lesions. Histology demonstrated diffuse lymphoid infiltrate which stained positive for CD20. Clonality studies confirmed low grade B cell MALT lymphoma. She was treated with anti CD20 monoclonal antibody, rituximab. Prognosis of pMALT is good with 5-year survival >80%. Thus, an index of suspicion and early detection are vital. This case highlights that pMALT should be considered in patients with non-specific symptoms and coeliac disease. Bronchoscopy is a valuable diagnostic tool to be used in these cases.

Primary pulmonary mucosa-associated lymphoid tissue lymphoma: A case report

Primary pulmonary lymphoma (PPL) is a rare entity with the most common presentation as mediastinal lymphadenopathy. The most common form of PPL is Mucosa-Associated Lymphoid Tissue Lymphoma (MALToma) which is an extranodal B-cell lymphoma originating from the mucosal layers involving different organs such as the gastrointestinal tract as well as the lung. Herein, we present a case of a 51-year-old woman with progressive dyspnea for 6 months and no prior medical history. The computed tomography (CT scan) revealed bilateral multifocal consolidation and ground-glass opacities as well as interlobular septal thickening. Bronchoscopy was normal and CT-guided biopsy of lung consolidations was conclusive of MALToma. Complete extrapulmonary evaluations inducing bone marrow aspiration were unremarkable. The primary pulmonary MALToma is an extremely rare entity that presents with non-specific symptoms and a wide variety of CT findings such as mediastinal, hilar lymphadenopathy, and single or multiple lung nodules ranging from 2 to 8 cm. the disease has a favorable prognosis, so prompt diagnosis is essential.

Mucosa-Associated Lymphoid Tissue (MALT) Lymphoma in the Gastrointestinal Tract in the Modern Era

Extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma) typically arises from sites such as the stomach, where there is no organized lymphoid tissue. Close associations between Helicobacter pylori and gastric MALT lymphoma or Campylobacter jejuni and immunoproliferative small intestinal disease (IPSID) have been established. A subset of tumors is associated with chromosomal rearrangement and/or genetic alterations. This disease often presents as localized disease, requiring diverse treatment approaches, from antibiotic therapy to radiotherapy and immunochemotherapy. Eradication therapy for H. pylori effectively cures gastric MALT lymphoma in most patients. However, treatment strategies for H. pylori-negative gastric MALT lymphoma are still challenging. In addition, the effectiveness of antibiotic therapy has been controversial in intestinal MALT lymphoma, except for IPSID. Endoscopic treatment has been noted to usually achieve complete remission in endoscopically resectable colorectal MALT lymphoma with localized disease. MALT lymphoma has been excluded from post-transplant lymphoproliferative disorders with the exception of Epstein-Barr virus (EBV)-positive marginal zone lymphoma (MZL). We also describe the expanding spectrum of EBV-negative MZL and a close association of the disease with the gastrointestinal tract.

Recent Advances in the Genetic of MALT Lymphomas

Simple Summary

Mucosa-associated lymphoid tissue (MALT) lymphoma is the most common subtype of marginal zone lymphomas. These B-cell neoplasms may arise from many organs and usually have an indolent behavior. Recurrent chromosomal translocations and cytogenetic alterations are well characterized, some of them being associated to specific sites. Through next-generation sequencing technologies, the mutational landscape of MALT lymphomas has been explored and available data to date show that there are considerable variations in the incidence and spectrum of mutations among MALT lymphoma of different sites. Interestingly, most of these mutations affect several common pathways and some of them are potentially targetable. Gene expression profile and epigenetic studies have also added new information, potentially useful for diagnosis and treatment. This article provides a comprehensive review of the genetic landscape in MALT lymphomas.

Abstract

Mucosa-associated lymphoid tissue (MALT) lymphomas are a diverse group of lymphoid neoplasms with B-cell origin, occurring in adult patients and usually having an indolent clinical behavior. These lymphomas may arise in different anatomic locations, sharing many clinicopathological characteristics, but also having substantial variances in the aetiology and genetic alterations. Chromosomal translocations are recurrent in MALT lymphomas with different prevalence among different sites, being the 4 most common: t(11;18)(q21;q21), t(1;14)(p22;q32), t(14;18)(q32;q21), and t(3;14)(p14.1;q32). Several chromosomal numerical abnormalities have also been described, but probably represent secondary genetic events. The mutational landscape of MALT lymphomas is wide, and the most frequent mutations are: TNFAIP3, CREBBP, KMT2C, TET2, SPEN, KMT2D, LRP1B, PRDM1, EP300, TNFRSF14, NOTCH1/NOTCH2, and B2M, but many other genes may be involved. Similar to chromosomal translocations, certain mutations are enriched in specific lymphoma types. In the same line, variation in immunoglobulin gene usage is recognized among MALT lymphoma of different anatomic locations. In the last decade, several studies have analyzed the role of microRNA, transcriptomics and epigenetic alterations, further improving our knowledge about the pathogenic mechanisms in MALT lymphoma development. All these advances open the possibility of targeted directed treatment and push forward the concept of precision medicine in MALT lymphomas.

Combined detection of lymphocyte clonality and MALT1 translocations in bronchoalveolar lavage fluid for diagnosing pulmonary lymphomas

Diagnosis of pulmonary lymphoma using small tissue samples is difficult and often requires surgical procedures; thus, a less invasive sampling method is desirable. We previously showed that pulmonary mucosa-associated lymphoid tissue (MALT) lymphoma can be diagnosed by detecting MALT lymphoma translocation gene 1 (MALT1) translocations in bronchoalveolar lavage fluid (BALF) cells. Analysis of B-cell clonality based on immunoglobulin heavy chain (IGH) gene rearrangements was also reportedly useful for diagnosing pulmonary lymphoma. The aim of this prospective multicenter study was to evaluate the yet unknown diagnostic potential of combined detection of MALT1 translocations and clonality using BALF. We analyzed B- and T-cell clonality based on IGH and T-cell receptor (TCR) rearrangements together with MALT1 translocations using BALF of patients with clinically suspected pulmonary lymphomas. In total, 39 patients were evaluated and categorized into three groups: B-cell lymphoma, lymphoproliferative disorders, and other diseases. IGH rearrangement detection for B-cell lymphoma diagnosis exhibited sensitivity and specificity of 88.9% and 90.0%, respectively. TCR rearrangements were not observed in patients with B-cell lymphomas. The presence of IGH rearrangements together with the absence of TCR rearrangements indicated 96.0% specificity for the diagnosis of B-cell lymphoma. The sensitivity and specificity of MALT1 translocations for diagnosing MALT lymphoma were 28.6% and 100%, respectively. The combined detection of lymphocyte clonality and MALT1 translocations using BALF is suitable for screening and diagnosis of B-cell lymphomas. Analysis of specific genes such as MALT1 should improve the precision of B-cell lymphoma diagnosis.

A single-center analysis of patients with extranodal marginal zone lymphoma of the breast

Breast extranodal marginal zone lymphoma (EMZL) is a rare malignancy. We performed the largest published to date single-center retrospective analysis of 13 patients with breast EMZL focusing on clinical characteristics and treatment-related outcomes. The rarity of this disease at our center was concordant with the prevalence reported in the literature, with breast EMZL comprising 2% of 654 MZL cases. Most patients presented with stage I-II disease however four (30.8%) patients had stage IV disease mostly due to occult bone marrow (BM) involvement. Interestingly, EMZL was frequently non-FDG avid (66.7%) on staging PET/CT. With a median follow-up of 3.1 years (range 5 months to 10.2 years), the 3-year progression free survival was 68.7% (95%CI 30.2%-88.9%) and overall survival 80.2% (95%CI 40.3%-94.8%). No patient experienced higher-grade transformation. Herein we show that localized breast EMZL can be effectively treated with radiation therapy providing long term disease control.

DNA Methylation-Based Classification of Small B-Cell Lymphomas: A Proof-of-Principle Study

Although most small B-cell lymphomas (SBCLs) can be diagnosed using routine methods, challenges exist. For example, marginal zone lymphomas (MZLs) can be difficult to rule-in, in large part because no widely-used, sensitive, and specific biomarker is available for the marginal zone cell of origin. In this study, it was hypothesized that DNA methylation array profiling can assist with the classification of SBCLs, including MZLs. Extramedullary SBCLs, including challenging cases, were reviewed internally for pathology consensus and profiled. By combining the resulting array data set with data sets from other groups, a set of 26 informative probes was selected and used to train machine learning models to classify 4 common SBCLs: chronic lymphocytic leukemia/small lymphocytic lymphoma, follicular lymphoma, mantle cell lymphoma, and MZL. Prediction probability cutoff was used to separate classifiable from unclassifiable cases, and show that the trained model was able to classify 95% of independent test cases (n = 264/279). The concordance between model predictions and pathology diagnoses was 99.6% (n = 262/263) among classifiable test cases. One validation reference test case was reclassified based on model prediction. The model was also used to predict the diagnoses of two challenging SBCLs. Although the differential examined and data on difficult cases are limited, these results support accurate methylation-based classification of SBCLs. Furthermore, high specificities of predictions suggest that methylation signatures can be used to rule-in MZLs.

Clinicopathological aspects of primary mucosa-associated lymphoid tissue lymphoma of the salivary gland: A retrospective single-center analysis of 72 cases

BACKGROUND

Salivary gland extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue lymphoma (MALT lymphoma) is uncommon and has not been studied extensively. We aimed to investigate the features of clinicopathological and molecular changes of salivary MALT lymphoma.

METHODS

Seventy-two cases of primary salivary MALT lymphoma that had clinicopathological information available were utilized in this study. MALT1 gene translocation, trisomy 3, and trisomy 18 were detected by interphase fluorescence in situ hybridization (FISH). The data were analyzed using SPSS 17.0 software package.

RESULTS

The ratio of male to female was 1:2.8, and the median age was 57.0 years. 12.5% (9/72) of the patients presented with multiple swellings. Among the others with solitary mass, the parotid gland was involved most frequently (47/63,74.6%), followed by the palate (7/63, 11.1%). 34.7% of patients had an autoimmune disease, with Sjögren syndrome (SS) being the most common. Among the 70 cases successfully performed, it was identified that trisomy 3 was the most frequent molecular change (41/70, 58.6%), followed by trisomy 18 (7/70, 10%) and MALT1 translocation (5/70, 7.1%). The tumor tissue tended to exhibit trisomy 3 in patients without SS (p = 0.038). The 5-year overall survival was 94.1%, and the 5-year disease-free survival was 85.3% (mean follow-up time: 104.7 months). The patients without SS and trisomy 18 had a prolonged recurrence-free survival (p = 0.015, p = 0.001 respectively).

CONCLUSION

Salivary gland MALT lymphoma is associated with autoimmune diseases, and trisomy 3 is the most common genetic change. Trisomy 18 can be used to predict the possibility of tumor relapse.

A Review of Genetic Abnormalities in Unicentric and Multicentric Castleman Disease

Castleman disease (CD) is a rare lymphoproliferative disorder known to represent at least four distinct clinicopathologic subtypes. Large advancements in our clinical and histopathologic description of these diverse diseases have been made, resulting in subtyping based on number of enlarged lymph nodes (unicentric versus multicentric), according to viral infection by human herpes virus 8 (HHV-8) and human immunodeficiency virus (HIV), and with relation to clonal plasma cells (POEMS). In recent years, significant molecular and genetic abnormalities associated with CD have been described. However, we continue to lack a foundational understanding of the biological mechanisms driving this disease process. Here, we review all cases of CD with molecular abnormalities described in the literature to date, and correlate cytogenetic, molecular, and genetic abnormalities with disease subtypes and phenotypes. Our review notes complex karyotypes in subsets of cases, specific mutations in PDGFRB N666S in 10% of unicentric CD (UCD) and NCOA4 L261F in 23% of idiopathic multicentric CD (iMCD) cases. Genes affecting chromatin organization and abnormalities in methylation are seen more commonly in iMCD while abnormalities within the mitogen-activated protein kinase (MAPK) and interleukin signaling pathways are more frequent in UCD. Interestingly, there is a paucity of genetic studies evaluating HHV-8 positive multicentric CD (HHV-8+ MCD) and POEMS-associated CD. Our comprehensive review of genetic and molecular abnormalities in CD identifies subtype-specific and novel pathways which may allow for more targeted treatment options and unique biologic therapies.

Laboratory Workup of Lymphoma in Adults: Guideline From the American Society for Clinical Pathology and the College of American Pathologists

CONTEXT.—

The diagnostic workup of lymphoma continues to evolve rapidly as experience and discovery led to the addition of new clinicopathologic entities and techniques to differentiate them. The optimal clinically effective, efficient, and cost-effective approach to diagnosis that is safe for patients can be elusive, in both community-based and academic practice. Studies suggest that there is variation in practice in both settings.

OBJECTIVE.—

To develop an evidence-based guideline for the preanalytic phase of testing, focusing on specimen requirements for the diagnostic evaluation of lymphoma.

DESIGN.—

The American Society for Clinical Pathology, the College of American Pathologists, and the American Society of Hematology convened a panel of experts in the laboratory workup of lymphoma to develop evidence-based recommendations. The panel conducted a systematic review of literature to address key questions. Using the Grading of Recommendations Assessment, Development, and Evaluation approach, recommendations were derived based on the available evidence, strength of that evidence, and key judgements as defined in the Grading of Recommendations Assessment, Development, and Evaluation Evidence to Decision framework.

RESULTS.—

Thirteen guideline statements were established to optimize specimen selection, ancillary diagnostic testing, and appropriate follow-up for safe and accurate diagnosis of indolent and aggressive lymphoma.

CONCLUSIONS.—

Primary diagnosis and classification of lymphoma can be achieved with a variety of specimens. Application of the recommendations can guide decisions on specimen suitability, diagnostic capabilities, and correct use of ancillary testing. Disease prevalence in patient populations, availability of ancillary testing, and diagnostic goals should be incorporated into algorithms tailored to each practice environment.

No evidence for a pathogen associated with pulmonary MALT lymphoma: a metagenomics investigation

Mucosa-associated lymphoid tissue (MALT) lymphoma is generally associated with chronic antigen stimulation: auto-antigens or of microbial origin. Only one study suggested association between Achromobacter xylosoxidans and pulmonary MALT lymphoma. We aimed to investigate the presence of virus or any infectious agents in pulmonary MALT lymphoma by using metagenomic next-generation sequencing (mNGS).

All lung samples were centrally reviewed. The t(11;18) (q21;q21) was evaluated by FISH analysis. The snap frozen large lung biopsies were analyzed by mNGS. After lung biopsies homogenization total nucleic acids (RNA and DNA) were extracted, amplified and classified according to their taxonomic assignment, after exclusion of host DNA.

We included 13 samples from pulmonary MALT lymphoma (mean age: 60.3 years, 7 women, 3 with auto-immune background) and 10 controls. The diagnosis of MALT lymphoma was confirmed for the 13 samples, 3 showed API2-MALT1 translocation (23%). No evidence of the presence of a specific pathogen was clearly identified in the group of patients with pulmonary MALT lymphoma. We identifiedA. xylosoxidans sequence in 4/13 patients and in 4/10 controls.

This study did not find evidence for a DNA or RNA virus, a fungi, a parasite or a bacteria associated with pulmonary MALT lymphoma either in the stroma or in tumor cells.

Deciphering the genetic landscape of pulmonary lymphomas

Pulmonary lymphoid malignancies comprise various entities, 80% of them are pulmonary marginal zone B-cell lymphomas (PMZL). So far, little is known about point mutations in primary pulmonary lymphomas. We characterized the genetic landscape of primary pulmonary lymphomas using a customized high-throughput sequencing gene panel covering 146 genes. Our cohort consisted of 28 PMZL, 14 primary diffuse large B-cell lymphomas (DLBCL) of the lung, 7 lymphomatoid granulomatoses (LyG), 5 mature small B-cell lymphomas and 16 cases of reactive lymphoid lesions. Mutations were detected in 22/28 evaluable PMZL (median 2 mutation/case); 14/14 DLBCL (median 3 mutations/case) and 4/7 LyG (1 mutation/case). PMZL showed higher prevalence for mutations in chromatin modifier-encoding genes (44% of mutant genes), while mutations in genes related to the NF-κB pathway were less common (24% of observed mutations). There was little overlap between mutations in PMZL and DLBCL. MALT1 rearrangements were more prevalent in PMZL than BCL10 aberrations, and both were absent in DLBCL. LyG were devoid of gene mutations associated with immune escape. The mutational landscape of PMZL differs from that of extranodal MZL of other locations and also from splenic MZL. Their landscape resembles more that of nodal MZL, which also show a predominance of mutations of chromatin modifiers. The different mutational composition of pulmonary DLBCL compared to PMZL suggests that the former probably do not present transformations. DLBCL bear more mutations/case and immune escape gene mutations compared to LyG, suggesting that EBV infection in LyG may substitute for mutations.

Primary Pulmonary B-Cell Lymphoma: A Review and Update

Simple Summary

The group of B-cell lymphomas primarily involving the lung encompasses different histological entities with distinct biological aspects, while sharing some clinical and radiological features related to their common anatomic site of occurrence. Recent molecular advances in the molecular genetics of these lesions have substantially improved of our understanding of the mechanisms of lymphomagenesis, adding novel information to histology in order to better characterize and manage these diseases. This review summarizes the available clinical, radiological, pathological, and molecular data on primary pulmonary B-cell lymphomas, discusses the mechanisms of lymphomagenesis, and highlights the role of a multi-disciplinary management in overcoming the diagnostic and therapeutic challenges in this setting.

Abstract

Primary pulmonary B-cell lymphomas (PP-BCLs) comprise a group of extranodal non-Hodgkin lymphomas of B-cell origin, which primarily affect the lung without evidence of extrapulmonary disease at the time of diagnosis and up to 3 months afterwards. Primary lymphoid proliferations of the lung are most often of B-cell lineage, and include three major entities with different clinical, morphological, and molecular features: primary pulmonary marginal zone lymphoma of mucosa-associated lymphoid tissue (PP-MZL, or MALT lymphoma), primary pulmonary diffuse large B cell lymphoma (PP-DLBCL), and lymphomatoid granulomatosis (LYG). Less common entities include primary effusion B-cell lymphoma (PEL) and intravascular large B cell lymphoma (IVLBCL). A proper workup requires a multidisciplinary approach, including radiologists, pneumologists, thoracic surgeons, pathologists, hemato-oncologists, and radiation oncologists, in order to achieve a correct diagnosis and risk assessment. Aim of this review is to analyze and outline the clinical and pathological features of the most frequent PP-BCLs, and to critically analyze the major issues in their diagnosis and management.

Laboratory Workup of Lymphoma in Adults

OBJECTIVES

The diagnostic workup of lymphoma continues to evolve rapidly as experience and discovery lead to the addition of new clinicopathologic entities and techniques to differentiate them. The optimal clinically effective, efficient, and cost-effective approach to diagnosis that is safe for patients can be elusive, in both community-based and academic practice. Studies suggest that there is variation in practice in both settings.

THE AIM OF THIS REVIEW IS TO

develop an evidence-based guideline for the preanalytic phase of testing, focusing on specimen requirements for the diagnostic evaluation of lymphoma.

METHODS

The American Society for Clinical Pathology, the College of American Pathologists, and the American Society of Hematology convened a panel of experts in the laboratory workup of lymphoma to develop evidence-based recommendations. The panel conducted a systematic review of the literature to address key questions. Using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach, recommendations were derived based on the available evidence, the strength of that evidence, and key judgments as defined in the GRADE Evidence to Decision framework.

RESULTS

Thirteen guideline statements were established to optimize specimen selection, ancillary diagnostic testing, and appropriate follow-up for safe and accurate diagnosis of indolent and aggressive lymphoma.

CONCLUSIONS

Primary diagnosis and classification of lymphoma can be achieved with a variety of specimens. Application of the recommendations can guide decisions about specimen suitability, diagnostic capabilities, and correct utilization of ancillary testing. Disease prevalence in patient populations, availability of ancillary testing, and diagnostic goals should be incorporated into algorithms tailored to each practice environment.

Recent advances upper gastrointestinal lymphomas: molecular updates and diagnostic implications

Approximately one-third of extranodal non-Hodgkin lymphomas involve the gastrointestinal (GI) tract, with the vast majority being diagnosed in the stomach, duodenum, or proximal small intestine. A few entities, especially diffuse large B-cell lymphoma and extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue, represent the majority of cases. In addition, there are diseases specific to or characteristic of the GI tract, and any type of systemic lymphoma can present in or disseminate to these organs. The recent advances in the genetic and molecular characterisation of lymphoid neoplasms have translated into notable changes in the classification of primary GI T-cell neoplasms and the recommended diagnostic approach to aggressive B-cell tumours. In many instances, diagnoses rely on morphology and immunophenotype, but there is an increasing need to incorporate molecular genetic markers. Moreover, it is also important to take into consideration the endoscopic and clinical presentations. This review gives an update on the most recent developments in the pathology and molecular pathology of upper GI lymphoproliferative diseases.

Extranodal Marginal Zone Lymphoma of the Central Nervous System Includes Parenchymal-Based Cases With Characteristic Features

OBJECTIVES

To define the clinicopathologic features of extranodal marginal zone lymphoma (EMZL) of the central nervous system (CNS), including cases arising in CNS parenchyma, which have been reported only rarely.

METHODS

Twelve cases of CNS EMZL were identified, including 5 based in CNS parenchyma and 7 nonparenchymal cases arising in dura or choroid plexus.

RESULTS

Histologically, parenchymal cases were perivascular infiltrates without a dominant lymphoid mass, whereas nonparenchymal cases were masses of small lymphocytes. Plasma cells were a larger component of the infiltrate in parenchymal cases (median, 30%; range, 20%-50%) than nonparenchymal cases (median, 0%; range, 0%-5%; P < .001), and plasma cells were clonal by immunohistochemistry in 4 of 5 parenchymal vs 1 of 7 nonparenchymal cases (P = .07). Fluorescence in situ hybridization for MALT1 rearrangement was positive in 1 of 3 parenchymal and none of 3 nonparenchymal cases. Chromosomal microarray was abnormal in 5 of 7 cases (71%), with chromosome 6/6q alterations identified in 3 cases. No patients with parenchymal disease but all 6 (100%) with nonparenchymal disease achieved complete remission.

CONCLUSIONS

This case series, the first to include multiple parenchymal cases, clarifies the spectrum of clinical, pathologic, and genetic findings in CNS EMZL and suggests that parenchymal-based lesions may show less favorable prognosis than dural-based disease.

t(3;14)(p14.1;q32)/FOXP1-IGH translocation in thyroid extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma)

OBJECTIVES

MALT lymphoma occurs in various organs and has several characteristic genetic aberrations. Thyroid MALT lymphoma has been reported to include t(3;14)(p14.1;q32)/FOXP1-IGH as a specific genetic aberration, but the number of studies is limited.

METHOD AND RESULTS

We examined 86 thyroid lymphoma cases using fluorescence in situ hybridization (FISH) for the detection of t(3;14)/FOXP1-IGH in formalin fixed paraffin-embedded tissue (FFPE). Histopathological diagnoses of the analyzed specimen were as follows: thyroid MALT lymphoma (n = 59), DLBCL (n = 23), follicular lymphoma (n = 4), and benign lesions (n = 14) included Hashimoto's thyroiditis (n = 13) and other (n = 1). Of the 100 analyzed cases, thirty-six (36 %) thyroid lymphoma cases were positive for t(3;14)/FOXP1-IGH. Thirty-three (55.9 %) of the 59 MALT lymphoma cases were positive for t(3;14)/FOXP1-IGH. Three (13.0 %) of the 23 DLBCL cases were positive for t(3;14)/FOXP1-IGH. All 4 follicular lymphomas examined were negative for t(3;14)/FOXP1-IGH. None of the benign cases was positive for t(3;14)/FOXP1-IGH, including Hashimoto's thyroiditis (0/13) and benign tissue (0/1).

CONCLUSIONS

Our study found that t(3;14)/FOXP1-IGH was frequently found in thyroid MALT lymphoma. A detection of t(3;14)/FOXP1-IGH is extremely useful for the differential diagnosis between primary MALT lymphoma of the thyroid and other thyroid disorders.

MALT lymphoma of the colon: a clinicopathological review

Extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma) occurs in approximately 9% of non-Hodgkin B cell lymphoma. However, it occurs only rarely within the colon. The presentation is often asymptomatic, and can have multiple endoscopic appearances, including a single or multinodular polypoid lesion. Furthermore, small biopsies can make histological evaluation challenging. The 2016 WHO classification update includes many molecular features of entities and expands the differential diagnosis of lymphoid lesions of the colon. In addition to immunohistochemistry, molecular methods may be tempting to use for small difficult cases. Furthermore, treatment approaches are varied for this entity, and not well studied. Therefore, an updated review on MALT lymphoma of the colon is needed.

Endoscopic features of esophageal adenocarcinoma derived from short-segment versus long-segment Barrett's esophagus

BACKGROUND AND AIM

The study aims to clarify the endoscopic features and clinicopathological differences in superficial Barret's esophageal adenocarcinoma (s-BEA) derived from short-segment Barrett's esophagus (SSBE) and long-segment Barrett's esophagus (LSBE).

METHODS

We reviewed data of 130 patients (141 lesions) with pathologically confirmed s-BEA (SSBE: 95 patients and 95 lesions; LSBE: 35 patients and 46 lesions). We analyzed endoscopic and clinicopathological features of s-BEA in patients with SSBE and LSBE.

RESULTS

The distribution of lesions according to macroscopic findings were as follows (s-BEA in SSBE vs LSBE): flat type (0-IIb), 3.2% (3/95) vs 32.6% (15/46) (P < 0.001); accompanied type 0-IIb, 2.1% (2/95) vs 21.7% (10/46) (P < 0.001); and complex type (0-I + IIb, 0-IIa + IIc, etc.), 30.5% (29/95) vs 50.0% (23/46) (P = 0.025). Complex-type s-BEAs had high incidences of T1b invasions and poorly differentiated components (simple type: 22.5% [20/89] and 18.0% [16/89]; complex type: 59.6% [31/52] and 44.2% [23/52], P < 0.001 and P = 0.002, respectively). In SSBE, 72.6% (69/95) of lesions were located at the right anterior wall (P = 0.01). All flat-type or depressed-type lesions derived from SSBE were identified as reddish areas, whereas only 65.2% (15/23) from LSBE were identified as reddish areas (P < 0.001).

CONCLUSIONS

In LSBE, flat-type, accompanied-type 0-IIb, and complex-type lesions were significantly more prevalent. Furthermore, complex-type s-BEAs tended to have T1b invasions and poorly differentiated components. S-BEAs in LSBE should be more carefully evaluated on endoscopic appearance including flat-type and complex-type lesions than in SSBE.

The role of infectious agents in cancer of the ocular region

The purpose of the study was to investigate the association between infectious agents and the development of cancer in the ocular adnexa. A comprehensive literary study was carried out, reviewing and summarizing previous reports on the topic. A broad range of malignancies of the ocular adnexa are associated with infectious agents. A strong association and possible causal relationship between the infectious agent and the development of ocular adnexal cancer are seen in Merkel cell carcinoma (Merkel cell polyomavirus), Burkitt lymphoma (Epstein-Barr virus) and Kaposi sarcoma (human herpesvirus 8). Infection with Chlamydia psittaci has been associated with the development of extranodal marginal zone B-cell lymphoma in Italy. Human papillomavirus infection has been associated with the development of squamous cell carcinomas of the ocular adnexa, although with a highly variable reported prevalence. By exploring the role of infectious agents in the ocular adnexa and the mechanism by which they contribute to oncogenesis, the diagnostics, management and prevention of these malignancies may also improve. Antibiotic treatment and vaccines against infectious agents may be valuable in future treatment. Additionally, the presence of infectious agents within the tumours may have a prognostic or predictive value.

miR-3687 Overexpression Promotes Bladder Cancer Cell Growth by Inhibiting the Negative Effect of FOXP1 on Cyclin E2 Transcription

Cyclin E2, a member of the cyclin family, is a key cell cycle-related protein. This protein plays essential roles in cancer progression, and, as such, an inhibitor of cyclin E2 has been approved to treat several types of cancers. Even so, mechanisms underlying how to regulate cyclin E2 expression in cancer remain largely unknown. In the current study, miR-3687 was upregulated in clinical bladder cancer (BC) tumor tissues, The Cancer Genome Atlas (TCGA) database, and human BC cell lines. Inhibition of miR-3687 expression significantly reduced human BC cell proliferation in vitro and tumor growth in vivo, which coincided with the induction of G₀/G₁ cell cycle arrest and downregulation of cyclin E2 protein expression. Interestingly, overexpression of cyclin E2 reversed the inhibition of BC proliferation induced by miR-3687. Mechanistic studies suggested that miR-3687 binds to the 3' UTR of foxp1 mRNA, downregulates FOXP1 protein expression, and in turn promotes the transcription of cyclin E2, thereby promoting the growth of BC cells. Collectively, the current study not only establishes a novel regulatory axis of miR-3687/FOXP1 regarding regulation of cyclin E2 expression in BC cells, but also provides strong suggestive evidence that miR-3687 and FOXP1 may be promising targets in therapeutic strategies for human BC.

Lymphomas of the head and neck region: an update

The field of haematopathology is rapidly evolving and for the non-specialized pathologist receiving a specimen with the possibility of a lymphoid malignancy may be a daunting experience. The coincidence of the publication, in 2017, of the WHO monographies on head and neck and haematopoietic and lymphoid tumours prompted us to write this review. Although not substantially different from lymphomas elsewhere, lymphomas presenting in this region pose some specific problems and these are central to the review. In addition, differences in subtype frequency and morphological variations within the same entity are discussed. The difficulty in diagnosis related to some specimens led us to briefly mention common subtypes of systemic lymphomas presenting in the head and neck region.

High Frequency of MYD88 L265P Mutation in Primary Ocular Adnexal Marginal Zone Lymphoma and Its Clinicopathologic Correlation: A Study From a Single Institution

CONTEXT.—

The pathogenesis of primary ocular adnexal marginal zone lymphoma (POAMZL) remains unclear. The reported associations with Chlamydia psittaci infection and MYD88 mutations are highly variable.

OBJECTIVE.—

To examine MYD88 L265P mutation in ocular marginal zone lymphomas and correlate with clinicopathologic features and Chlamydia infection.

DESIGN.—

Presence of MYD88 L265P mutation and Chlamydia infection in lymphoma was analyzed by using sensitive polymerase chain reaction (PCR) methods.

RESULTS.—

The MYD88 L265P mutation was identified in 8 of 22 POAMZLs (36%), including 2 of 3 cases in which PCR failed to detect clonal IGH gene rearrangement; none of the 4 secondary marginal zone lymphomas were positive. Test results for Chlamydia were negative in all cases. Patients with and without the MYD88 mutation had similar clinicopathologic features.

CONCLUSIONS.—

The MYD88 mutational analysis provides important information in diagnostic workup of POAMZL. The frequent MYD88 mutation suggests a critical role of this aberration in the pathogenesis of POAMZL and may serve as a therapeutic target for patients with progressive disease.

Pulmonary extranodal marginal zone lymphoma that presented with macroglobulinemia and marked plasmacytic cell proliferation carrying the t(14;18)(q32;q21)/MALT1-immunoglobulin heavy-chain fusion gene in pleural fluid

An 80-year-old man presented with the accumulation of pleural fluid in the right thoracic cavity. Serum electrophoresis revealed an M-component and immunofixation confirmed IgM/λ. The level of IgM was 1,526 mg/dL. Imaging studies showed an infiltrative condition of the ipsilateral lung parenchyma. The fluid contained abundant neoplastic cells with the morphological and immunophenotypic features of plasma cells, which expressed IgM/λ monoclonal immunoglobulins on the cell surface and in the cytoplasm. The karyotype was 48,XY,+3,add(9)(p13),+12,add(14)(q32),del(16)(q22),−18,+mar, and a series of fluorescence in situ hybridization studies demonstrated that the add(14) chromosome represented der(14)t(14;18)(q32;q21), at which the MALT1-immunoglobulin heavy-chain (IGH) fusion gene was localized. A long-distance polymerase chain reaction amplified the fragment encompassing the two genes, showing that the junction occurred at the J6 segment of IGH and 3.7-kb upstream of the MALT1 breakpoint cluster. We propose that this case represents an extreme form of the plasmacytic differentiation of extranodal marginal zone lymphoma that developed in the lung.

Fluorescent In Situ Hybridization in Surgical Pathology Practice

There have been rapid and significant advances in diagnostic and predictive molecular techniques in recent years with profound impact on patient care. In situ hybridization (ISH) studies have become well entrenched in surgical pathology practice and their role in the evaluation of HER2 in breast carcinoma and their diagnostic utility in soft tissue pathology are well known. Fluorescent ISH is being increasingly used in other sites such as the head and neck and the gynecologic tract. Like most tests in surgical pathology, ISH studies require good quality tissue, correlation with clinical and histopathologic findings, and adherence to guidelines for optimal assay performance and interpretation. Although ISH studies are largely performed in tertiary centers, the tissue is often processed by a variety of laboratories and the referring pathologists are required to discuss the need, relevance, and significance of these tests and the results with their clinical colleagues. Here we review the predictive and diagnostic utility of fluorescent ISH studies in a variety of organ systems, the preanalytical factors that may affect the results, and the pitfalls in the interpretation that all practicing surgical pathologists should be aware of.

Inferior survival in high-grade B-cell lymphoma with MYC and BCL2 and/or BCL6 rearrangements is not associated with MYC/IG gene rearrangements

High-grade B-cell lymphomas with MYC and BCL2 and/or BCL6 rearrangements (double-/triple-hit lymphoma) have an aggressive clinical course. We investigated the prognostic value of transformation from low-grade lymphoma, cytological features (high grade versus large cell), MYC rearrangement partners (immunoglobulin versus nonimmunoglobulin gene), and treatment. We evaluated 100 adults with double-/triple-hit lymphoma, reviewing cytological features; cell of origin; and rearrangements of MYC, BCL2, and BCL6 using MYC, BCL2, and BCL6 break-apart and IGH/MYC, IGL/MYC, IGK/MYC, and IGH/BCL2 dual-fusion interphase fluorescence in situ hybridization probes. Outcome analysis was restricted to patients with lymphoma, de novo or at transformation, who received anthracycline-based chemotherapy. Among them, 60% had high-grade cytological features; 91% had a germinal center B-cell phenotype, and 60% had a MYC/IG rearrangement. Germinal center B-cell phenotype was associated with BCL2 rearrangements (P<0.001). Mean (95% confidence interval) 5-year overall survival was 49% (37%–64%). Transformation from previously treated and untreated low-grade lymphoma was associated with inferior overall survival (hazard ratio, 2.99; P=0.008). Patients with high-grade cytological features showed a non-significant tendency to inferior outcome (hazard ratio, 2.32; P=0.09). No association was observed between MYC rearrangement partner and overall survival (hazard ratio, 1.00; P=0.99). Compared with patients receiving rituximab, cyclophosphamide, doxorubicin, and vincristine (R-CHOP) and dose-adjusted etoposide, prednisone, vincristine, cyclophosphamide, doxorubicin, and rituximab (EPOCH-R), patients receiving rituximab, cyclophosphamide, vincristine, doxorubicin, methotrexate/ifosfamide, etoposide, and cytarabine (R-CODOX-M/IVAC) had a non-significant tendency to better overall survival (hazard ratio, 0.37; P=0.10). In conclusion, high-grade B-cell lymphomas with MYC and BCL2 and/or BCL6 rearrangements had heterogeneous outcomes and MYC/IG rearrangements were not associated with inferior overall survival.

The Diagnosis of Gastric Mucosa-associated Lymphoid Tissue Lymphoma by Flow Cytometry and Fluorescence in situ Hybridization of Biopsy Specimens

Mucosa-associated lymphoid tissue (MALT) lymphoma and reactive inflammatory lymphoid changes are frequently difficult to distinguish based on a routine histological differential diagnosis. We were unable to diagnose gastric MALT lymphoma histologically using specimens obtained by endoscopy, although a flow cytometry (FCM) analysis demonstrated clonality of neoplastic cells by separating cells by CD45 gating. Furthermore, a fluorescence in situ hybridization (FISH) analysis showed trisomy 18. We therefore diagnosed gastric MALT lymphoma with trisomy 18. We recommend that FCM and FISH analyses of biopsy specimens be considered for diagnosing gastric MALT lymphoma if this diagnosis is suspected based on endoscopic findings.

Recent advances in understanding the biology of marginal zone lymphoma

There are three different marginal zone lymphomas (MZLs): the extranodal MZL of mucosa-associated lymphoid tissue (MALT) type (MALT lymphoma), the splenic MZL, and the nodal MZL. The three MZLs share common lesions and deregulated pathways but also present specific alterations that can be used for their differential diagnosis. Although trisomies of chromosomes 3 and 18, deletions at 6q23, deregulation of nuclear factor kappa B, and chromatin remodeling genes are frequent events in all of them, the three MZLs differ in the presence of recurrent translocations, mutations affecting the NOTCH pathway, and the transcription factor Kruppel like factor 2 ( KLF2) or the receptor-type protein tyrosine phosphatase delta ( PTPRD). Since a better understanding of the molecular events underlying each subtype may have practical relevance, this review summarizes the most recent and main advances in our understanding of the genetics and biology of MZLs.

Management of gastric mucosa-associated lymphoid tissue lymphoma in patients with extra copies of the MALT1 gene

AIM

To identify the clinical features of gastric mucosa-associated lymphoid tissue (MALT) lymphoma with extra copies of MALT1.

METHODS

This is a multi-centered, retrospective study. We reviewed 146 patients with MALT lymphoma in the stomach who underwent fluorescence in situ hybridization analysis for t(11;18) translocation. Patients were subdivided into patients without t(11;18) translocation or extra copies of MALT1 (Group A, n = 88), patients with t(11;18) translocation (Group B, n = 27), and patients with extra copies of MALT1 (Group C, n = 31). The clinical background, treatment, and outcomes of each group were investigated.

RESULTS

Groups A and C showed slight female predominance, whereas Group B showed slight male predominance. Mean ages and clinical stages at lymphoma diagnosis were not different between groups. Complete response was obtained in 61 patients in Group A (69.3%), 22 in Group B (81.5%), and 21 in Group C (67.7%). Helicobacter pylori (H. pylori) eradication alone resulted in complete remission in 44 patients in Group A and 13 in Group C. In Group B, 14 patients underwent radiotherapy alone, which resulted in lymphoma disappearance. Although the difference was not statistically significant, event-free survival in Group C tended to be inferior to that in Group A (P = 0.10).

CONCLUSION

Patients with t(11;18) translocation should be treated differently from others. Patients with extra copies of MALT1 could be initially treated with H. pylori eradication, similar to patients without t(11;18) translocation or extra copies of MALT1.

Clinical aspects and therapy of gastrointestinal MALT lymphoma

Extranodal marginal zone B-cell lymphomas of the mucosa associated lymphoid tissue (MALT) arise from lymphoid populations that are induced by chronic inflammation in extranodal sites. Among the MALT lymphomas, gastrointestinal (GIT) MALT lymphoma is the most frequent compared to non-GIT MALT lymphoma arising from other sites. Gastric MALT lymphoma has been the first to be described with the evidence of an etiopathogenetic link provided by the association between Helicobacter pylori-positive gastritis and gastric MALT lymphoma. Indeed, successful eradication of this micro-organism with antibiotics can be followed by a lymphoma regression in most cases. When there is no association with Helicobacter pylori, there is no clear therapeutic consensus. Both radiotherapy and systemic treatments with chemotherapy and anti-CD20 antibodies are efficacious and thus the experience of individual centers and each patient's preferences in terms of adverse effects are important parameters in the decision process.

B-cell Non-Hodgkin Lymphomas with Plasmacytic Differentiation

B-cell non-Hodgkin lymphomas with plasmacytic differentiation are a diverse group of entities with extremely variable morphologic features. Diagnostic challenges can arise in differentiating lymphoplasmacytic lymphoma from marginal zone lymphoma and other low-grade B-cell lymphomas. In addition, plasmablastic lymphomas can be difficult to distinguish from diffuse large B-cell lymphoma or other high-grade lymphomas. Judicious use of immunohistochemical studies and molecular testing can assist in appropriate classification.

Epidemiology and environmental aspects of marginal zone lymphomas

Marginal zone lymphomas (MZLs) account for between 5% and 17% of all non-Hodgkin's lymphomas. MZLs consist of 3 different subtypes with extranodal being the most commonly reported, representing 50-70% of MZL, followed by splenic (20%) and nodal (10%). Median age at presentation varies between these lymphoma sub-types, ranging between 50 and 69 years, with an overall greater incidence noted in males compared to females. Given the rarity of these lymphomas, epidemiologic data has been sparse, although it has been suggested the aetiology is multi-factorial including ethnicity and geographical factors. Other reported associations include autoimmune disease and infection, with Helicobacter pylori and Campylobacter psittaci, being the most commonly reported pathogens. Larger population studies are required to investigate the role of these environmental factors further as these can direct the future management of these lymphomas, through the use of more effective targeted treatments.

The spectrum of MALT lymphoma at different sites: biological and therapeutic relevance

Extranodal marginal zone (MZ) B-cell lymphomas of the mucosa-associated lymphoid tissue (MALT) arise from lymphoid populations that are induced by chronic inflammation in extranodal sites. The best evidence of an etiopathogenetic link is provided by the association between Helicobacter pylori–positive gastritis and gastric MALT lymphoma. Indeed, successful eradication of this microorganism with antibiotics can be followed by gastric MALT lymphoma regression in most cases. Other microbial agents have been implicated in the pathogenesis of MZ lymphoma arising at different sites. Apart from gastric MALT lymphoma, antibiotic therapies have been adequately tested only in ocular adnexal MALT lymphomas where upfront doxycycline may be a reasonable and effective initial treatment of patients with Chlamydophila psittaci–positive lymphoma before considering more aggressive strategies. In all other instances, antibiotic treatment of nongastric lymphomas remains investigational. Indeed, there is no clear consensus for the treatment of patients with gastric MALT lymphoma requiring further treatment beyond H pylori eradication or with extensive disease. Both radiotherapy and systemic treatments with chemotherapy and anti-CD20 antibodies are efficacious and thus the experience of individual centers and each patient’s preferences in terms of adverse effects are important parameters in the decision process.

LMO2 Is a Specific Marker of T-Lymphoblastic Leukemia/Lymphoma

OBJECTIVES

The diagnosis of T-lymphoblastic leukemia/lymphoma (T-ALL) involving the thymus can be difficult to establish since neoplastic T lymphoblasts show significant phenotypic overlap with both normal thymocytes and thymocytes from epithelial thymic neoplasms (thymomas). LIM Domain Only 2 (LMO2) gene translocations have been implicated in the pathogenesis of a small subset of T-ALLs, and LMO2 protein has recently been reported to be expressed in a large proportion of T-ALLs.

METHODS

In this study, we tested specificity of LMO2 for distinction between neoplastic and nonneoplastic T-precursor cells in thymus and bone marrow.

RESULTS

Our findings show that LMO2 is expressed in neoplastic lymphoblasts of T-ALL and is absent in thymocytes of normal thymuses or thymomas.

CONCLUSIONS

LMO2 is therefore a useful marker for immunophenotypic assessment of thymic neoplasms.

Pulmonary mucosa-associated lymphoid tissue lymphoma revisited

This general review sought to clarify the pathophysiological, diagnostic, prognostic, and therapeutic features of pulmonary mucosa-associated lymphoid tissue (MALT) lymphoma.MALT lymphoma is the most common pulmonary B-cell lymphoma, which usually occurs in the context of acquired MALT. The disease is slow-growing with an asymptomatic chronic alveolar opacity visible on radiography. Diagnosis requires tissue samples that should be retrieved using minimally invasive techniques, such as bronchoscopy or computed tomography-guided biopsies. The pathophysiology includes cytogenetic abnormalities and autoimmune diseases, whereas an association with a chronic pulmonary infection is still suspected but not yet demonstrated. Disease prognosis is typically excellent and the current available treatments are discussed in this review, including the decision not to treat, surgery, and single- or double-agent chemotherapy.

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.