Trisomy 3 may predict a poor response of gastric MALT lymphoma to Helicobacter pylori eradication therapy

Gastric Mucosa-associated Lymphoid Tissue Lymphoma That Relapsed after 11 Years Subsequent to Achieving Complete Remission

A 38-year-old Japanese man was diagnosed with extranodal marginal zone lymphoma of the mucosa-associated lymphoid tissue in the stomach (gastric MALT lymphoma). Fluorescence in situ hybridization analysis revealed the absence of t (11;18) (q21;q21) translocation but the presence of extra copies of MALT1, indicating tetrasomy 18. Helicobacter pylori eradication led to complete remission (CR). However, the gastric MALT lymphoma relapsed after 11 years old. This case underscores the need for long-term observation (>10 years) of patients with gastric MALT lymphoma. Further investigation is warranted to elucidate the correlation between trisomy/tetrasomy 18 and the recurrence propensity.

Effectiveness of Helicobacter pylori eradication in the treatment of early-stage gastric mucosa-associated lymphoid tissue lymphoma: An up-to-date meta-analysis

BACKGROUND

Gastric mucosa-associated lymphoid tissue (MALT) lymphoma (GML) is usually a low-grade B-cell neoplasia strongly associated with Helicobacter pylori (H. pylori)-induced chronic gastritis. Clinical practice guidelines currently recommend H. pylori eradication as the preferred initial treatment for early-stage GML. To determine the practical effect of bacterial eradication as the sole initial therapy for early-stage GML, an updated analysis and review of available evidence is imperative.

AIM

To perform a meta-analysis to assess the rate of complete remission (CR) of H. pylori-positive early-stage GML following bacterial eradication.

METHODS

We performed independent, computer-assisted literature searches using the PubMed/MEDLINE, Embase, and Cochrane Central databases through September 2022. Prospective and retrospective observational studies evaluating the CR of early-stage GML following bacterial eradication in H. pylori-positive patients. The risk of bias was assessed using Joanna Briggs Institute (JBI) Critical Appraisal Tools. The pooled estimate of the complete histopathological remission rate and respective confidence intervals (95%CI) were calculated following the random-effects model. Heterogeneity and inconsistency were assessed using Cochran’s Q test and I² statistic, and heterogeneity was defined as P < 0.01 and I² > 50%, respectively. Subgroup and meta-regression analyses were conducted to explore potential sources of heterogeneity.

RESULTS

The titles and abstracts of 1576 studies were screened; 96 articles were retrieved and selected for full-text reading. Finally, 61 studies were included in the proportional meta-analysis (P-MA). Forty-six were prospective and fifteen were retrospective uncontrolled, single-arm, observational studies. The overall risk of bias was low to moderate in all but a single report, with an average critical appraisal score across all studies of 79.02%. A total of 2936 H. pylori-positive early-stage GML patients, in whom H. pylori was successfully eradicated, were included in the analysis. The pooled CR of H. pylori-positive early-stage GML after bacterial eradication was 75.18% (95%CI: 70.45%-79.91%). P-MA indicated the substantial heterogeneity in CR reported across studies (I² = 92%; P < 0.01). Meta-regression analysis identified statistically significant effect modifiers, including the proportion of patients with t(11;18)(q21;q21)-positive GML and the risk of bias in each study.

CONCLUSION

Comprehensive synthesis of available evidence suggests that H. pylori eradication is effective as the sole initial therapy for early-stage GML. Although the substantial heterogeneity observed across studies limits the interpretation of the pooled overall CR, the present study is a relevant to informing clinical practice.

Impact of the microenvironment on the pathogenesis of mucosa-associated lymphoid tissue lymphomas

Approximately 8% of all non-Hodgkin lymphomas are extranodal marginal zone B cell lymphomas of mucosa-associated lymphoid tissue (MALT), also known as MALT lymphomas. These arise at a wide range of different extranodal sites, with most cases affecting the stomach, the lung, the ocular adnexa and the thyroid. The small intestine is involved in a lower percentage of cases. Lymphoma growth in the early stages is associated with long-lasting chronic inflammation provoked by bacterial infections (e.g., Helicobacter pylori or Chlamydia psittaci infections) or autoimmune conditions (e.g., Sjögren’s syndrome or Hashimoto thyroiditis). While these inflammatory processes trigger lymphoma cell proliferation and/or survival, they also shape the microenvironment. Thus, activated immune cells are actively recruited to the lymphoma, resulting in either direct lymphoma cell stimulation via surface receptor interactions and/or indirect lymphoma cell stimulation via secretion of soluble factors like cytokines. In addition, chronic inflammatory conditions cause the acquisition of genetic alterations resulting in autonomous lymphoma cell growth. Recently, novel agents targeting the microenvironment have been developed and clinically tested in MALT lymphomas as well as other lymphoid malignancies. In this review, we aim to describe the composition of the microenvironment of MALT lymphoma, the interaction of activated immune cells with lymphoma cells and novel therapeutic approaches in MALT lymphomas using immunomodulatory and/or microenvironment-targeting agents.

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.

Efficacy of eradication therapy in Helicobacter pylori-negative gastric mucosa-associated lymphoid tissue lymphoma: A meta-analysis

BACKGROUND AND AIMS

The role of eradication therapy in Helicobacter pylori-negative gastric mucosa-associated lymphoid tissue (MALT) lymphoma remains controversial. The aim of this study was to investigate the efficacy of H. pylori eradication therapy as a first-line treatment for H. pylori-negative gastric MALT lymphoma.

METHODS

A literature search of studies published until October 2019 was performed using electronic databases. Studies that reported treatment response to eradication therapy as an initial treatment for patients with H. pylori-negative gastric MALT lymphoma were eligible for inclusion. The primary outcome was the complete remission rate after eradication therapy.

RESULTS

Twenty-five studies were included in the analyses. The overall pooled complete remission rate was 29.3% (95% confidence interval [CI], 22.2%-37.4%, I²  = 41.5%). There was no publication bias, and the sensitivity analyses showed consistent results. The pooled complete remission rates were lower in the subgroups of studies that had a higher incidence of translocation t(11;18)(q21;q21) (19.9%, 95% CI, 11.6%-32.0%), studies that used serological tests to exclude H. pylori infection (27.5%, 95% CI, 20.1%-36.4%), and studies where non-response to eradication therapy was determined at <12 months after treatment (27.0%, 95% CI, 15.5%-42.7%). Meta-regression analysis revealed that the pooled estimate was not significantly different in terms of the characteristics of individual studies.

CONCLUSIONS

Although the complete remission rate after eradication therapy is not high, it can be used as an initial treatment option in a subset of patients with H. pylori-negative gastric MALT lymphoma. Further studies to identify subgroups of patients who may benefit from eradication therapy are needed.

Histopathological landscape of rare oesophageal neoplasms

The landscape of neoplastic pathology of the oesophagus is dominated by malignancies of epithelial origin, in particular by oesophageal adenocarcinoma and oesophageal squamous cell carcinoma. However, several other histopathological variants can be distinguished, some associated with peculiar histopathological profiles and prognostic behaviours and frequently underrecognized in clinical practice. The aim of this review is to provide a comprehensive characterization of the main morphological and clinical features of these rare variants of oesophageal neoplastic lesions.

Flow cytometric, gene rearrangement, and karyotypic analyses of 110 cases of primary thyroid lymphoma: a single-institutional experience in Japan

Ancillary studies for primary nodal lymphomas have been well documented; however, studies of primary thyroid lymphoma (PTL) are limited. Here, we aimed to clarify the clinicopathological, flow cytometric, gene rearrangement, and karyotypic characteristics of PTL by investigation of a large series at a single institute. We performed flow cytometric, IgH rearrangement, and karyotypic analyses of 110 PTL tissues surgically resected at Kuma Hospital between January 2012 and April 2017. All PTLs were of B-cell origin, including mucosa-associated lymphoid tissue lymphoma (MALTL; 89 patients, 80.9%), diffuse large B-cell lymphoma (DLBCL; 18 patients, 16.4%), and follicular lymphoma (FL; three patients, 2.7%). In 96 (87.3%) patients, anti-thyroid antibodies were positive. For flow cytometry using aspirated and resected materials, light chain restriction was observed in 73.7% and 69.2% of examined cases, respectively. Heavy chain JH DNA rearrangement was observed in 65.4% of PTLs (58.1% of MALTL cases, 100% of DLBCL cases, and 100% of FL cases). Chromosomal abnormalities were detected in 49.0% of PTLs, and translocation was most frequently detected (24.0%), followed by addition (20.8%) and trisomy (18.8%). The most frequent (9.4%) karyotype was t(3;14)(q27;q32). Both FLs harbored t(14;18)(q32;q21), and the karyotype was not detected in patients with MALTL and DLBCL. The negative rate for all three examinations was 3.8%. We concluded that thyroid MALTL was cytogenetically different from that in other organs. Our results suggested that pre-operative flow cytometry analysis using aspirated materials was as reliable as that using resected materials.

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.

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.

Primary esophageal mucosa-associated lymphoid tissue lymphoma: A case report and review of literature

RATIONALE

Mucosa-associated lymphoid tissue (MALT) lymphoma is a low grade malignant B cell lymphoma which occurs mainly in the organs having mucosal layer. Though gastrointestinal tract is the most commonly involved extranodal site, primary esophageal MALT lymphoma is very rare with less than 20 cases reported in literature.

PATIENT CONCERNS

A 75-year-old man was referred to our hospital for evaluation of dysphagia. Endoscopy revealed a submucosal tumor located in the middle and lower third of esophagus. CT chest and endoscopic ultrasound revealed a 15.5 × 5.9 × 4.0 cm well circumscribed submucosa esophageal tumor. Test for serum antibody against H. pylori was negative. Due to the large tumor size, patient underwent surgical resection. Histological examination showed a submucosal tumor consisting of multiple nodules of varying sizes with intact covering squamous epithelium. The nodules were mainly composed of diffusely and monoclonal proliferating centrocyte-like or monocyte-like cells. Follicular colonizations were observed without lymphoepithelial lesions. The tumor cells were diffusely positive for CD20, PAX-5, Bcl-2 and follicular dendritic cells were positive for CD21, CD23. Monoclonal gene rearrangement was positive for immunoglobulin heavy chain gene, Kappa light chain gene and Lambda light chain gene.

DIAGNOSES

Based on these findings, final diagnosis of esophageal MALT lymphoma was made.

OUTCOMES

At 8 month follow up, no recurrence or metastases was detected.

LESSONS

Esophageal MALT lymphoma is a rare disease with definitive diagnosis possible only after histopathological examination. It carries good prognosis due to low malignant potential.

Nodal Marginal Zone Large B-Cell Lymphoma with Burkitt Translocation and Complex Chromosomal Changes Associated with Overexpression of BCL2, MYC, and BCL6

We report the first case of a nodal marginal zone large B-cell lymphoma and the first with MYC rearrangement. This high proliferation rate lymphoma (40% of cells) occurred in the bilateral cervical, axillary, and para-aortic lymph nodes of an 82 year old woman. It involved extensively her bone marrow, and was lethal. Malignant B-cells were CD10 negative, harbored Burkitt translocation, and multiple chromosomal changes including trisomies of chromosomes 3 and 18, and three copies of 8q with an intact q24 cytoband (in addition to MYC rearrangement), associated with overexpression of BCL6, BCL2, and MYC respectively. We suggest that in aggressive nodular marginal zone lymphomas (clinical picture or high proliferation rate of lymphoma cells), fluorescence in situ hybridization analysis for MYC rearrangement, with break-apart probe, and for MYC/IGH translocation, in addition to chromosome analysis, should be performed. MYC rearrangement associated with a more rapid progression of the neoplasia, might warrant a more aggressive treatment.

Molecular Pathogenesis of MALT Lymphoma

Approximately 8% of all non-Hodgkin lymphomas are extranodal marginal zone B cell lymphoma of mucosa associated lymphoid tissue (MALT), also known as MALT lymphoma, which was first described in 1983 by Isaacson and Wright. MALT lymphomas arise at a wide range of different extranodal sites, with the highest frequency in the stomach, followed by lung, ocular adnexa, and thyroid, and with a low percentage in the small intestine. Interestingly, at least 3 different, apparently site-specific, chromosomal translocations and missense and frameshift mutations, all pathway-related genes affecting the NF-κB signal, have been implicated in the development and progression of MALT lymphoma. However, these genetic abnormalities alone are not sufficient for malignant transformation. There is now increasing evidence suggesting that the oncogenic product of translocation cooperates with immunological stimulation in oncogenesis, that is, the association with chronic bacterial infection or autoaggressive process. This review mainly discusses MALT lymphomas in terms of their genetic aberration and association with chronic infections and summarizes recent advances in their molecular pathogenesis.

Recurrence after radiotherapy for gastric mucosa-associated lymphoid tissue (MALT) lymphoma with trisomy 18

A 36-year-old Japanese woman presented with extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma) in the stomach. The gastric lesions only partially improved after eradication therapy for Helicobacter pylori. A fluorescence in situ hybridization analysis revealed no fusion genes of API2-MALT1, although trisomy of chromosome 18 was identified. Radiation therapy was initiated to treat the gastric lymphoma lesions, resulting in complete remission. However, MALT lymphoma recurred in the stomach 16 months later. This case indicates that intensive follow-up is required for MALT lymphoma associated with chromosomal aberrations in order to detect early relapse.

Chromosomal abnormalities by conventional cytogenetics and interphase fluorescence in situ hybridization in chronic lymphocytic leukemia in Taiwan, an area with low incidence--clinical implication and comparison between the West and the East

Chronic lymphocytic leukemia (CLL) is much less prevalent in Taiwan than in the West, but we have recently addressed the distinctly increasing incidence of CLL in Taiwan. We sought to find out whether there is any difference in cytogenetic abnormalities (CA) of CLL between the West and the East. We analyze the CA, by conventional cytogenetics (CG) and fluorescence in situ hybridization (FISH), and their clinical significance in 83 Taiwanese CLL patients and compared the data to those of Western countries. Thirty-five patients (42.2 %) possessed CG-CA and 58 (69.9 %) FISH-CA. By either CG or FISH, deletion of 17p or 11q was associated with poorer overall survival (OS) (P<0.001 and P=0.008, respectively), whereas isolated 13q deletion was associated with better OS (P=0.050). Trisomy 3 by CG was found in five patients; all of them were in Binet A stage but had strikingly poor OS (P<0.001). This prognostic impact was independent from the other CA and Binet stages. We conclude that, though the disease incidence is much different, the CA of CLL in Taiwan are similar to those in the West. The combined CG and FISH analysis is able to predict the patients' prognosis. The clinical significance of trisomy 3 warrants further validation.

Characterization of chromosomal aberrations in thymic MALT lymphoma

Mucosa-associated lymphoid tissue (MALT) lymphoma arising in the thymus is a rare disorder that shows a strong association with autoimmune disease. Several MALT-lymphoma-specific and -associated chromosomal abnormalities, including t(11;18), t(14;18), t(1;14), trisomy 3 and trisomy 18, are known to occur. The former translocation results in apoptosis inhibitor 2 gene (API2)-MALT lymphoma-associated translocation 1 (MALT1) fusion. In this study, we examined 14 cases of thymic MALT lymphomas for API2-MALT1 fusion using multiplex reverse transcription polymerase chain reaction and looked for trisomy 3, trisomy 18 and abnormalities of MALT1 and IGH genes using fluorescence in situ hybridization. Thymic MALT lymphoma cases had a high frequency of trisomy 3 (7/14 cases), a very low incidence of trisomy 18 (1/14) and no detectable MALT1-associated (0/13) or IGH-associated (0/13) gene abnormalities including t(11;18). A review of the literature showed that the pattern of chromosomal aberrations in thymic MALT lymphoma was similar to those of thyroid and salivary gland MALT lymphomas. Although frequently detected, trisomy 3 was not associated with any of the clinicopathological factors analyzed, suggesting that trisomy 3 may play a role in lymphoma development. In conclusion, the present study showed that thymic MALT lymphoma has a characteristic pattern of chromosomal aberrations that may be similar to those of other autoimmune-associated MALT lymphomas.

Analysis of API2-MALT1 fusion, trisomies, and immunoglobulin VH genes in pulmonary mucosa-associated lymphoid tissue lymphoma

Pulmonary mucosa-associated lymphoid tissue lymphoma is unique in that chronic inflammation is rare and that API2-MALT1 fusion, resulting from t(11;18)(q21;q21), occurs frequently. In this study, we examined 20 cases for API2-MALT1 fusion using the multiplex reverse-transcription polymerase chain reaction and looked for trisomy 3, trisomy 18, and abnormalities of MALT1 and IGH genes using fluorescence in situ hybridization. In addition, we analyzed VH genes by subcloning of the monoclonal polymerase chain reaction products. Of 20 cases studied, we detected gene abnormalities in 16: API2-MALT1 fusion in 9, trisomy 3 in 5, trisomy 18 in 4, MALT1 abnormality in 13, and IGH abnormality in 1. MALT1 gene abnormalities were concordant with API2-MALT1 fusion or trisomy 18. One case showed API2-MALT1 fusion and trisomy 3. On detection of API2-MALT1 fusion and trisomies, we were able to divide our cases into 3 groups, API2-MALT1 positive, trisomy positive, and no detectable gene abnormality, suggesting that tumor development had processed along different genetic pathways. All 20 cases were analyzed for VH genes. Most of the VH genes selected by the lymphomas belonged to the VH3 family, but there was no restriction to any particular VH fragment. Of interest, VH genes were unmutated in 7 cases, suggesting that T-cell-independent extrafollicular B-cell maturation may be important in the development of this lymphoma. In addition, both mutated and unmutated tumor cases were found to carry the API2-MALT1 fusion and trisomy 3. This observation suggests that these gene abnormalities may occur in microenvironments found before or outside of follicular germinal centers.

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

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

Advances on the treatment of gastric mucosa-associated lymphoid tissue lymphoma

Gastric mucosa-associated lymphoid tissue (MALT) lymphomas are rare in the gut, and its occurrence rate was 1% to 5% of the malignant tumors. In histological type, most of them are non-Hodgin's lymphomas, while Hodgin's lymphomas are seldom seen. There have been a lot of controversies on the optimal treatments of gastric MALT lymphomas for a long time. Surgery was traditionally considered as the most important approach to cure the disease. However, anti-H. pylori therapy has been regarded as an alternative method since H. pylori infection was found to be relevant with the pathogenesis of gastric MALT lymphomas. In this article, we reviewed the current status and recent advances on the treatment of this disease.

FISH analysis for the detection of lymphoma-associated chromosomal abnormalities in routine paraffin-embedded tissue

Over the last decade, fluorescence in situ hybridization (FISH) has become a firmly established technique in the diagnosis and assessment of lymphoid malignancies. However, this technique is not wide-ly used in the routine diagnostic evaluation of paraffin-embedded biopsies, most likely because of a perception that it is technically more demanding. There are also uncertainties regarding diagnostic thresholds and the way in which results should be interpreted. In this Review, we describe practical strategies for using FISH analysis to detect lymphoma-associated chromosomal abnormalities in routine paraffin-embedded lymphoma biopsies. Furthermore, we provide proposals on how FISH results should be interpreted (including how to calculate cutoff levels for FISH probes), recorded, and reported. An online appendix (available at http://jmd.amjpathol.org) details various simple, yet robust procedures for paraffin FISH analysis; it also provides additional information on the production of FISH probes, evaluating and reporting FISH results, sources for reagents and equipment, and troubleshooting. We hope that these suggestions will make FISH technology for the study of lymphoma biopsies more accessible to routine diagnostic and research laboratories.

Successful antibiotic treatment of Helicobacter pylori negative gastric mucosa associated lymphoid tissue lymphomas

BACKGROUND AND AIMS

The role of antibiotic treatment in early stage gastric mucosa associated lymphoid tissue (MALT) lymphoma not associated with Helicobacter pylori infection has not been investigated.

PATIENTS AND METHODS

Six patients with localised gastric MALT lymphoma underwent antibiotic treatment with clarithromycin, metronidazole, and pantoprazole. Staging, including endosonography plus gastroscopy, computed tomography of the thorax and abdomen, colonoscopy, magnetic resonance imaging of the salivary glands, and bone marrow biopsy were performed to rule out distant spread of the disease. In addition, MALT specific genetic changes, including reverse transcriptase-polymerase chain reaction for t(11;18)(q21;q21), were tested in all patients. H pylori infection was ruled out by histology, urease breath test, serology, and stool antigen testing.

RESULTS

All six patients had MALT lymphoma restricted to the stomach, and no evidence of infection with H pylori was found. Only one patient tested positive for t(11;18)(q21;q21) while the remaining five displayed no genetic aberrations. Following antibiotic treatment, endoscopic controls were performed every three months. Five patients responded with lymphoma regression between three and nine months following antibiotic treatment (one partial remission and four complete responses). One patient had stable disease for 12 months and was then referred for chemotherapy.

CONCLUSIONS

Patients with early stage gastric MALT lymphoma negative for H pylori might still benefit from antibiotic treatment as the sole treatment modality.

Cytogenetic and clinicopathological characterization by fluorescence in situ hybridization on paraffin-embedded tissue sections of twenty-six cases with malignant lymphoma of small intestine

OBJECTIVE

In small intestinal malignant lymphoma (SIML), the correlation between specific chromosomal abnormalities and clinicopathological features remains unclear. The aim of this study was to determine the frequency of chromosomal translocations involving the BCL1, BCL2, c-MYC, BCL6 and MALT1 genes by using fluorescence in situ hybridization directly on paraffin-embedded tissue sections (tissue-FISH).

MATERIAL AND METHODS

Twenty-six cases diagnosed as having SIML between 1996 and 2003 were the subjects of the clinicopathological investigation conducted in this study. Tissue-FISH was performed with specific probes on paraffin-embedded tissue sections as described previously.

RESULTS

The primary site was frequently located at the duodenum (9 cases, 35%). In accordance with the World Health Organization classification, 14 (53%) cases were diagnosed as having diffuse large B-cell lymphoma (DLBCL) and 6 (23%) as marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue (MALT). Macroscopically, DLBCL and MALT lymphoma displayed various macroscopic features. Cytogenetically, IGH-BCL2 translocation was detected in 3 (21%) out of 14 DLBCL cases, but in none of the MALT lymphomas. BCL6 translocation was detected in 5 (35%) of 14 DLBCL cases and in 1 (17%) of 6 MALT lymphoma cases (17%). API2-MALT1 translocation was detected in 1 (7%) of 14 DLBCL cases and in 1 (17%) of 6 MALT lymphoma cases.

CONCLUSIONS

The duodenum was preferentially involved in SIML. DLBCL and MALT lymphoma showed various macroscopic features. Tissue-FISH analysis disclosed that DLBCL is cytogenetically heterogeneous. Furthermore, our study validated tissue-FISH as an additional promising diagnostic tool for detecting specific chromosomal translocations in NHL.

Radiation therapy for localized low-grade non-Hodgkin's lymphomas

The most common low grade B-cell non-Hodgkin's lymphomas are follicular lymphomas, and extranodal marginal zone lymphomas, also known as mucosa-associated lymphoid tissue (MALT) lymphomas. Localized presentations of follicular lymphoma occur in 20-30% of cases, while for MALT lymphomas, stage I-II disease presentations occur in 70-90%. These are radiation-sensitive lymphomas. Following moderate dose local radiation treatment (30-35 Gy) for these stage I and II low grade lymphomas, the clinical results indicate long-term local control and possible cure. While local control is achieved with minimal morbidity with involved-field radiation therapy, a significant proportion of patients relapse with systemic disease outside of radiation fields. For follicular lymphoma, this occurs in approximately 50% of patients after 15 years, and for non-gastric MALT lymphoma, 30-40% after 10 years. Although patients with relapsed systemic disease are not curable with chemotherapy, the disease often behaves in an indolent fashion and prolonged survival is observed. For gastric MALT lymphomas, radiation therapy is indicated in patients whose lymphoma did not respond to Helicobacter pylori eradication therapy, or in gastric lymphoma not related to this microorganism. The subject of causative agents responsible for non-gastric MALT lymphomas is under active study and the identification of putative microorganisms will lead to improved treatment strategies for these unusual lymphomas, similar to the success in gastric lymphomas over the last decade.