Clone-specific PCR reveals wide dissemination of gastric MALT lymphoma to the gastric mucosa

Positron emission tomography/magnetic resonance imaging (PET/MRI) vs. gastroscopy: Can it improve detection of extranodal marginal zone lymphomas of the stomach following H. pylori treatment?

INTRODUCTION

The stomach is the most common site of origin for extranodal marginal zone B-cell lymphoma of the mucosa-associated lymphoid tissue (MALT lymphoma). Antibiotic eradication of Helicobacter pylori (H. pylori) is the standard first-line treatment, with response assessment being performed by histological evaluation of multiple gastric biopsies.

AREAS COVERED

The objective of this review is to provide an update on results obtained using noninvasive methods, including magnetic resonance imaging (MRI), positron emission tomography combined with computed tomography (PET/CT), and most recently, PET/MRI for the assessment of disease extent and response to treatment in patients with gastric MALT lymphoma.

EXPERT OPINION

While CT is the officially recommended imaging technique, few studies in small cohorts have suggested that diffusion-weighted MRI shows higher sensitivity, also relative to 18 F-FDG PET/CT, for both gastric and nongastric MALT lymphomas. A recent prospective study using PET/MRI with the novel CXCR4-targeting radiotracer 68 Ga-Pentixafor suggested that, for patients with gastric MALT lymphoma after H. pylori eradication, this imaging technique may provide excellent accuracy (97%) for assessment of residual or recurrent disease. Although recent studies on CXCR4-targeting PET and to some extent also diffusion-weighted MRI are promising, there is insufficient evidence to suggest a change in clinical practice.

What you always wanted to know about gastric MALT-lymphoma: a focus on recent developments

The stomach is the most common site of origin for extranodal lymphomas, with extranodal marginal zone B-cell of the mucosa associated lymphoid tissue (MALT-lymphoma) being the predominant subtype. MALT-lymphoma develops in mucosa associated lymphoid structures acquired by infection or chronic antigenic stimuli and may therefore arise in almost any organ of the human body. In spite of histopathologic similarities between various organs upon first glance, recent findings suggest pronounced differences between different sites, with a variety of features specific to gastric MALT-lymphoma. The objective of this review is to sum up the current knowledge on pathogenesis, molecular pathology, clinical presentation and therapeutic approaches to gastric MALT-lymphoma with in-depth discussion of recent developments.

[Radiotherapy for localized gastric and orbital MALT lymphomas]

Primary gastric and orbital MALT lymphomas are both low grade (indolent) B-cell non-Hodgkin's lymphomas. Traditionally, these tumors are radiosensitive and have a good prognosis. In localized orbital and stages IE-IIE gastric MALT lymphomas without Helicobacter pylori infection or in case of persistent H. pylori infection after eradication therapy, several retrospective studies have shown that radiotherapy was an effective and well-tolerated treatment.

Recurrence patterns of mucose-associated lymphoid tissue lymphoma after definitive radiation treatment: A single center experience

OBJECTIVES

To evaluate the treatment outcomes in non-gastric and non-nodal mucose-associated lymphoid tissue (MALT) lymphoma patients treated by definitive radiation therapy (RT).

METHODS

A total of 134 patients were analyzed. The RT dose was 30.6 or 36 Gy.

RESULTS

The median follow-up duration for all patients was 51.1 months (range, 3.0-132.4 months). Among the 88 orbital MALT lymphoma patients, 12 had disease recurrence. There were 23 head and neck tumor patients. Two patients experienced relapse, all at out-of-field locations. Gastrointestinal MALT lymphoma was diagnosed in 13 patients, and three showed local (n = 1), distant (n = 1), or local/distant (n = 1) relapse.

CONCLUSION

RT alone is highly effective in achieving local control and long-term survival in localized MALT lymphoma. In orbital MALT, excellent local control is achieved, and relapse is predominantly observed in the contralateral eye. Other head and neck lymphomas are also well controlled.

Kyoto global consensus report on Helicobacter pylori gastritis

OBJECTIVE

To present results of the Kyoto Global Consensus Meeting, which was convened to develop global consensus on (1) classification of chronic gastritis and duodenitis, (2) clinical distinction of dyspepsia caused by Helicobacter pylori from functional dyspepsia, (3) appropriate diagnostic assessment of gastritis and (4) when, whom and how to treat H. pylori gastritis.

DESIGN

Twenty-three clinical questions addressing the above-mentioned four domains were drafted for which expert panels were asked to formulate relevant statements. A Delphi method using an anonymous electronic system was adopted to develop the consensus, the level of which was predefined as ≥80%. Final modifications of clinical questions and consensus were achieved at the face-to-face meeting in Kyoto.

RESULTS

All 24 statements for 22 clinical questions after extensive modifications and omission of one clinical question were achieved with a consensus level of >80%. To better organise classification of gastritis and duodenitis based on aetiology, a new classification of gastritis and duodenitis is recommended for the 11th international classification. A new category of H. pylori-associated dyspepsia together with a diagnostic algorithm was proposed. The adoption of grading systems for gastric cancer risk stratification, and modern image-enhancing endoscopy for the diagnosis of gastritis, were recommended. Treatment to eradicate H. pylori infection before preneoplastic changes develop, if feasible, was recommended to minimise the risk of more serious complications of the infection.

CONCLUSIONS

A global consensus for gastritis was developed for the first time, which will be the basis for an international classification system and for further research on the subject.

Extranodal and splenic small B-cell lymphoma

Although almost any non-Hodgkin lymphoma can involve the spleen or an extranodal site as part of more widely disseminated disease, there is a group of small B-cell lymphomas that specifically arise in these locations. These are important to recognise as some appear to have a behaviour and prognosis that is distinct from their nodal counterparts. In addition, there are entities that are specific to extranodal locations (such as extranodal marginal zone lymphoma) and to the red or white pulp of the spleen. In this review, the characteristics of these entities will be presented as well as clues to help distinguish lymphoma from reactive infiltrates in extranodal sites and measure to distinguish between small B-cell lymphomas encountered in the spleen and at extranodal locations.

Subcutaneous dissemination pattern in extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue lymphoma

BACKGROUND

Mucosa-associated lymphoid tissue (MALT) lymphoma is among the most common forms of extranodal lymphomas, but little is known about subcutaneous involvement in patients with non-primary cutaneous marginal zone lymphomas.

DESIGN AND METHODS

Patients with MALT lymphoma diagnosed and treated at our institution between 1999 and 2010 were analyzed for subcutaneous deposits from MALT lymphoma diagnosed in another organ. Histological, clinical and genetic findings were assessed.

RESULTS

Among 216 patients with MALT lymphoma, 12 had subcutaneous deposits from MALT lymphoma (5.5%). In two patients, these lesions were present at diagnosis, while they constituted the site of relapse at an interval between 5 to 144 months in the remaining cases. Interestingly, nine of the 12 patients with subcutaneous deposits had originally been diagnosed with MALT lymphoma of the ocular adnexa (total number=51; 20%), and the other three had MALT lymphoma in the breast (total number=5; 60%). None of the patients with gastric (n=86), salivary gland (n=32) or pulmonary (n=19) MALT lymphomas had subcutaneous involvement during a median follow-up time of 87 months (range; 4 to 119 months).

CONCLUSIONS

Our data show that subcutaneous MALT lymphoma involvement is a rare event in patients with prior non-cutaneous extranodal marginal zone lymphoma. However, it seems to be almost exclusively associated with MALT lymphoma of the ocular adnexa and the breast, suggesting as yet undefined interactions between potentially embryonically related organ systems.

Gastric lymphoma: the histology report

The diagnosis of gastric MALT lymphoma is frequently difficult for the general histopathologist. During recent years there have been relevant changes in the therapeutic approach to gastric MALT lymphoma and our knowledge about its pathogenesis has greatly improved. The management of this disease actually requires a close cooperation between the histopathologist and the clinicians. The histology report of biopsies of a newly diagnosed or of an already treated case implies information of clinical and therapeutical relevance. This paper aims at giving the histopathologist a general knowledge about the state of art of this disease and its management. The diagnostic process leading to a complete and competent report is then described step by step.

Diagnosis and staging in gastrointestinal lymphoma

The diagnosis gastrointestinal lymphoma can be made on endoscopic biopsies in the vast majority of cases. Definitive subtyping of the lymphoma according to the WHO classification with the use of additional immunological and molecular markers is the cornerstone for further decision making. Several lymphomas may occur multifocally or show both small cell and large cell components. Therefore, a second endoscopy with an extensive biopsy protocol (mapping) may be mandatory. Staging procedures are required for therapeutic decision making and should include CT-scan, laboratory studies and bone marrow examination as required in other lymphomas. Additional studies must be performed depending subtype and localisation of the lymphoma. In gastric lymphoma endosonography reveals prognostic information. In marginal zone lymphoma of MALT-type attention to other MALT-sites and autoimmune diseases is necessary. In enteropathy-associated T-cell lymphoma screening for coeliac disease and enteroscopy are required. In several lymphomas (diffuse large B-cell lymphoma and mantle cell lymphoma) a PET-scan is considered as standard of care. The value of staging procedures after treatment is less well defined. At least in gastric lymphomas, histology is the gold standard after treatment and during follow-up.

Early-stage gastric MALT lymphoma: is it a truly localized disease?

Early-stage gastric mucosa-associated lymphoid tissue lymphoma (GML) is considered a localized disease with an indolent course. Circulating malignant cells have been detected in other early-stage indolent lymphomas by molecular methods. We investigated the incidence of occult blood disease in early-stage GML patients, its impact on clinical outcome, and the similarity between blood and gastric lymphocytic clones. Sixty-two patients with localized GML were included in the study; 51 of them had Helicobacter pylori infection. Monoclonality was investigated by leader polymerase chain reaction. Sequencing was performed for the immunoglobulin variable gene (VH) analysis. Blood involvement was absent in all patients by conventional staging methods. In the whole group of 62 patients, the incidence of blood IgH rearrangement was 45%, and this did not correlate with baseline patient characteristics. The monoclonal blood and gastric products of five patients were sequenced and compared with each other. Clonal identity was evident in four of five patients. The VH3 gene was the most frequently used, both in the blood and in the stomach. Early-stage GML is not a truly localized disease because half the patients had a circulating clone, probably identical to the gastric one. The clinical significance of occult blood disease and the potential appropriate intervention need to be further investigated.

Long-term follow-up of gastrectomized patients with mucosa-associated lymphoid tissue lymphoma: need for a revisit of surgical treatment. Ann Surg. 2008;247:265-269. [PMID: 18216531 DOI: 10.1097/sla.0b013e3181582364]

BACKGROUND

Gastric mucosa-associated lymphoid tissue (MALT) lymphoma is characterized by multifocality of the tumors, which often scatter over the mucosa of the stomach and adjacent upper gastrointestinal tract, and is therefore theoretically not curable by surgical resection.

METHODS

We conducted a long-term follow-up study of 14 patients who received surgical treatment for gastric MALT lymphoma. Tissues from the surgical margins of the resected stomach were analyzed by polymerase chain reaction-based amplification of the complementarity-determining region 3 of the IgH gene for the presence of residual tumors. T (11;18)(q21;q21), a marker of Helicobacter pylori-independent MALT lymphoma, was analyzed by reverse transcription polymerase chain reaction. All living patients were restaged, and rebiopsied if suspicious lesions were identified.

RESULTS

At a median follow-up of 11.5 years, only 1 patient had evidence of tumor recurrence. Three patients with molecularly proven residual tumors in the surgical margin remained disease-free at 9.6 to 11.6 years. Five patients with t(11;18)(q21;q21) in the tumor cells were disease-free at 9.2 to 12.6 years.

CONCLUSION

Our results indicate that surgical resection is a highly curative treatment for gastric MALT lymphoma, even for patients with residual tumor cells in the surgical margins, and for patients with H. pylori-independent tumors. A revisit of surgical treatment for gastric MALT lymphoma is mandatory.

Therapy of gastric mucosa-associated lymphoid tissue lymphoma

Mucosa-associated lymphoid tissue (MALT) lymphoma is a relatively common lymphoma and comprises approximately 7% of all newly diagnosed non-Hodgkin's lymphoma. It is mainly located in the stomach and has become a focus of interest due to its unique pathophysiological link with Helicobacter pylori (HP) and the consecutive response to HP eradication therapy. In view of this, HP eradication has become standard treatment for patients with localised disease, and recent data have suggested that HP-negative patients might benefit from antibiotic treatment. In case of non-response, however, the standard approach in such patients is unclear. Both radiation and chemotherapy have shown promising results, and at present there is only one randomised study, which nevertheless suggests chemotherapy as management of choice. The objective of this review is, therefore, to summarise and evaluate the data available for treatment of gastric MALT lymphoma and to highlight potential focus for further research.

Reverse Transcription-PCR for t(11;18)(q21;q21) Staging and Monitoring in Mucosa-Associated Lymphoid Tissue Lymphoma

PURPOSE

Subclinical dissemination as well as persistence after therapy may be difficult to assess on clinical and histologic examinations in patients with mucosa-associated lymphoid tissue (MALT) lymphoma. We have analyzed the use of reverse transcription-PCR (RT-PCR) for the detection of t(11;18)(q21;q21) in histologically infiltrated and normal biopsies at diagnosis and during follow-up to determine its clinical and prognostic effect.

EXPERIMENTAL DESIGN

Twenty-one patients with t(11;18)(q21;q21)+ MALT lymphoma were included in this retrospective study. Presence of t(11;18)(q21;q21) was determined by RT-PCR done on 316 biopsies of various tissues obtained during staging and follow-up.

RESULTS

Infiltration with lymphoma was histologically detected in 67 of 316 biopsies, whereas molecular infiltration was established in 104 of 316 biopsies. All histologically positive specimens were also positive in RT-PCR. There was a good concordance (P = 0.0001) between histology and RT-PCR at the time of disease presentation with only one further infiltration site identified by RT-PCR. In 8 of 12 patients with persistent lymphoma, RT-PCR revealed tumor infiltration in histologically unsuspected sites. Eight of nine treated patients with histologic and clinical complete remission (CR) remained RT-PCR positive. CR on RT-PCR was achieved later than histologic CR (between 13-59 months) without any further therapy in five of these eight patients; only one patient with persistent t(11;18)(q21;q21) relapsed histologically.

CONCLUSIONS

This study shows the potential of RT-PCR for t(11;18)(q21;q21) done on routine paraffin-embedded specimens to identify disseminated disease in tissues otherwise not diagnostic of MALT lymphoma involvement. T(11;18)(q21;q21) persistence in patients with clinical and histologic CR does not necessarily require therapeutic intervention.

Assessment of Disease Dissemination in Gastric Compared With Extragastric Mucosa-Associated Lymphoid Tissue Lymphoma Using Extensive Staging: A Single-Center Experience

Purpose

Molecular data and preliminary clinical findings have suggested mucosa-associated lymphoid tissue (MALT) lymphoma as a multifocal disease in a high percentage of patients. We report our findings with an extensive staging routine applied in patients diagnosed with MALT lymphoma at our institution.

Patients and Methods

A total of 140 consecutive patients (61 with gastric and 79 with extragastric MALT lymphoma) underwent staging according to a standardized protocol. Staging included gastroscopy with multiple biopsies, endosonography of the upper GI tract, computed tomography of thorax and abdomen, lymph node sonography, colonoscopy with multiple biopsies, otorhinolaryngologic assessment, magnetic resonance imaging of salivary and lacrimal glands, and bone marrow biopsy. All lesions suggestive of lymphoma involvement were subjected to biopsy, if accessible, and biopsies were evaluated for MALT lymphoma–specific genetic aberrations by means of reverse transcriptase polymerase chain reaction and/or fluorescent in situ hybridization.

Results

Fifteen (25%) of 61 patients with gastric MALT lymphoma had multiorgan involvement, with dissemination beyond the GI tract in six patients. By contrast, significantly more patients with extragastric MALT lymphoma had dissemination to another MALT organ (37 of 79 patients, 46%; P = .045). Nine of these 37 patients had dissemination to the stomach. Only three (2%) of 140 patients had bone marrow involvement. Multifocality was significantly associated with t(11;18)(q21;q21) in gastric lymphomas (P = .045) and with trisomy 18 in extragastric lymphomas (P = .011).

Conclusion

Our findings suggest that MALT lymphoma frequently presents as a multifocal disease. Extragastric MALT lymphomas are significantly more prone to dissemination than gastric MALT lymphomas.

Dissemination of a Sjögren's syndrome-associated extranodal marginal-zone B cell lymphoma: circulating lymphoma cells and invariant mutation pattern of nodal Ig heavy- and light-chain variable-region gene rearrangements

OBJECTIVE

Both the genesis and outgrowth of extranodal marginal-zone B cell lymphomas (MZLs) of the mucosa-associated lymphoid tissue (MALT) type are generally thought to represent antigen-driven processes. We undertook this study to analyze lymphoma progression and dissemination outside of the MALT-type lesions.

METHODS

Histopathologic and Ig heavy- and light-chain variable-region gene (V(H/L)) analyses were performed in sequential tissue samples from a patient with primary Sjögren's syndrome (SS) with glandular (parotid) manifestations and subsequent nodal dissemination of a low-grade MZL.

RESULTS

This MZL expressed a CD20+,CD27+,sIgM/kappa+,IgD-,CD5-,CD10-,Bcl-6-,CD23-,p53-,p21-,MDM2- phenotype and mutated V(H)1-69/D2-21/J(H)4alpha-V(kappa)A27/J(kappa)2 Ig rearrangements. Notably, circulating lymphoma cells from the parotid glands occurred transiently in the patient's blood, as detected by single-cell polymerase chain reaction. In addition, 2 minor B cell clones (clones 2 and 3, with V(H)3-07/D3-22/J(H)3b-V(lambda)3L/J(lambda)2/3 and V(H)3-64/D3-03/J(H)2-V(kappa)A19/J(kappa)2 rearrangements, respectively) were also detected in the parotid glands and blood, and 1 of these (clone 2) was also detected in the lymph nodes. Ig V(H/L) analyses revealed ongoing (antigen-driven) mutations of the glandular lymphoma rearrangements, but an invariant mutation pattern of their nodal counterparts.

CONCLUSION

These data indicate coexpansion and transient (re)circulation of the lymphoma clone and 2 additional glandular B cell clones in a primary SS-associated extranodal MZL. Combined histologic and molecular features of the nodal lymphoma subclone reflect a process of "follicular colonization" that eventually froze the mutation machinery after accumulation of additional (antigen-driven) Ig V(H/L) mutations.

Phase II study of oxaliplatin for treatment of patients with mucosa-associated lymphoid tissue lymphoma

PURPOSE

Various chemotherapeutic regimens have been applied for treatment of mucosa-associated lymphoid tissue (MALT) lymphoma, but no standard regimen has been identified to date. In view of the activity of oxaliplatin (L-OHP) in various types of lymphoma, we performed a phase II study to evaluate the activity of L-OHP for treatment of MALT lymphoma. The primary objective of this study was to determine the objective response rate according to WHO standard criteria.

PATIENTS AND METHODS

A total of 16 patients with MALT lymphoma of various sites of origin (four of the ocular adnexa, five of the salivary glands, three of the stomach, two of the lung, and one of the colon and the breast) were administered L-OHP at a dose of 130 mg/m2 infused during 2 hours every 3 weeks. Restaging was performed every two cycles; treatment was continued until complete remission (CR) or for a maximum of six cycles in responders.

RESULTS

Sixty-five cycles were administered (median, four; range, two to six); toxicity consisted of transient sensory neuropathy in eight patients and nausea/emesis WHO grade 2 in two patients, whereas hematologic adverse effects (thrombocytopenia and leukocytopenia grade 2) occurred in only one patient each. Fifteen patients responded to chemotherapy, with nine achieving CR (56%), six (37.5%) achieving partial response, and one achieving stable disease; the median time to response was 4 months (range; 2 to 4 months).

CONCLUSION

These data suggest L-OHP is a highly active agent for treatment of MALT lymphoma. However, a longer follow-up is needed to judge whether these remissions are durable.

Metachronous gastric MALT lymphoma and early gastric cancer: is residual lymphoma a risk factor for the development of gastric carcinoma?

BACKGROUND

Helicobacter pylori plays a major role in the pathogenesis of primary gastric MALT lymphoma (GML) and gastric carcinoma. The occurrence of these two diseases metachronously in a same patient is a rare event.

PATIENTS AND METHODS

Gastric biopsies and gastrectomy resection specimens of four patients who developed GML and early gastric cancer (EGC) were analysed by morphology, immunohistochemistry and molecular biology.

RESULTS

Four patients (three males and one female; mean age 48 years) were diagnosed with GML. Helicobacter pylori infection was observed in three cases. Two patients had localized disease (stages IE and IIE, respectively) and were treated with H. pylori eradication therapy followed by an alkylating agent for one patient. Two patients had disseminated disease (stage IV), and were treated with an alkylating agent. Three cases were t(11;18) positive. All patients achieved initially complete lymphoma remission. Long-term endoscopic surveillance detected an EGC at the same location as the lymphoma in all patients at a mean time of 9.5 years (range 2.5-17 years) after lymphoma diagnosis. Gastrectomy specimens showed residual GML in all cases.

CONCLUSION

Prolonged residual GML could constitute an additional risk factor for the development of gastric carcinoma. Long-term endoscopic surveillance is mandatory in patients treated conservatively for gastric MALT lymphoma.

Gastrointestinal lymphoma: where morphology meets molecular biology

Primary gastrointestinal lymphomas are best exemplified by mucosa-associated lymphoid tissue (MALT) lymphoma of the stomach and enteropathy-type T-cell lymphoma (ETL). Both lymphomas were initially recognized on morphological grounds and their identification as distinct clinicopathological entities has subsequently been vindicated following integrated immunophenotypic, molecular, and cellular biological investigations. Delineation of the phenotypic, molecular, and biological properties of these lymphomas at various clinicopathological stages of their development has also provided critical information for the clinical management of patients with these diseases. Here, the histopathology and recent advances in phenotypic and molecular characterization of gastric MALT lymphoma and ETL and their applications in diagnosis and clinical management are reviewed.

Clinical, histological and molecular follow-up of 60 patients with gastric marginal zone lymphoma of mucosa-associated lymphoid tissue

The persistence of gastric lymphoma after Helicobacter pylori eradication may be difficult to evidence on endoscopic and histological examination. The aims of the study were to evaluate the detection of monoclonal immunoglobulin H (IgH) gene rearrangement in endoscopically infiltrated and normal mucosa at diagnosis and during follow-up in order to determine its clinical and prognostic impact. We studied 60 gastric marginal zone lymphomas of mucosa-associated lymphoid tissue (MALT), and IgH monoclonality was detected at diagnosis in 52 patients (87%). The endoscopically normal mucosa contained clonal lymphomatous cells in 69% of cases before remission. A complete histological remission (HR) was observed in 28 patients (47%). Among them, 23 were followed for molecular remission (MR). The median delay was 10 months to achieve HR and 18 months to achieve MR. Interestingly, patients with HR but not MR had a longer delay to achieve HR (21 months) (P=0.0006) and a more frequent clonal normal mucosa at diagnosis (88%) than patients with both HR and MR (10 months and 39%, respectively). The presence of monoclonal B cells at both infiltrated and normal sites may therefore identify patients with a longer delay to achieve complete response, suggesting that molecular dissemination may require therapeutic intensification.

Gastrointestinal tract cytology: advancing horizons

Tide and ebb of interest in gastrointestinal tract cytology has followed technical advances in this field over the last 60 years. Cytologic samples can be obtained using gastric lavage, abrasive balloons, mucosal brushing, and fine needle aspiration (under percutaneous image guidance, endoscope and endoscopic ultrasound guidance). These advances now allow simultaneous performance of brushing the abnormal mucosa, obtaining fine needle aspirates and excising mucosal biopsy samples for evaluation. Use of endoscopic ultrasound guided fine needle aspirates now help to obtain diagnosis of submucosal lesions, preoperative staging of gastrointestinal tract malignancies and help determine further management of patients. Such advances have brought pathologists to the forefront of the patient management team for the treatment of gastrointestinal tract lesions. This manuscript reviews the advantages and limitations of each cytology associated technique as well as reviews the salient diagnostic features, differential diagnosis and diagnostic pitfalls of gastrointestinal tract lesions. Finally, it suggests the modalities best suited to obtain diagnosis for various gastrointestinal tract lesions.

Molecular biology of gastric MALT lymphoma: application in clinical management

The development of gastric mucosa-associated lymphoid tissue (MALT) lymphoma depends critically on Helicobacter pylori infection. The bacterial infection stimulates the lymphoma B-cells through both direct (auto-antigen) and indirect (H. pylori specific intra-tumour T-cells) immunological stimulation. It also promotes the acquisition of genetic abnormality through activated neutrophils, which release oxygen reactive species. Malignant clones bearing t(11;18)(q21;q21) form lymphomas that are H. pylori growth independent. Those without t(11;18)(q21;q21) but with other genetic abnormality such as trisomy 3 depend critically on H. pylori mediated immune response at early stages and are therefore responsive to H. pylori eradication. However, at late stages when additional genetic defects such as t(1;14)(p22;q32) accumulate, the tumour may escape its growth dependence on H. pylori mediated immune response. Detection of these chromosomal translocations has significant implication in clinical management of patients with gastric MALT lymphoma.

A clinicopathological study of 152 surgically treated primary gastric lymphomas with survival analysis of 109 high grade tumours

AIMS

To describe the clinicopathological features of a large number of surgically treated and followed up primary gastric lymphomas and thereby gain a better understanding of their biology, with particular reference to the prognostic factors of high grade tumours.

METHODS

A retrospective study of 152 patients.

RESULTS

High grade gastric lymphomas, both pure and with a residual low grade component, differed from low grade mucosa associated lymphoid tissue (MALT)-type lymphomas in that they were more frequently large, ulcerated, at an advanced stage, and highly proliferating. In addition, patients were older and had a worse outcome. The prognosis of high grade lymphomas was influenced by patient age, tumour stage, depth of infiltration in the gastric wall, and the invasion of adjacent organs. Adjuvant postsurgical treatment prolonged survival only in patients with advanced stage and deep neoplastic infiltration.

CONCLUSIONS

There is a sharp distinction between low grade MALT-type lymphomas and tumours with a high grade component, justifying their different treatment approach. The postsurgical management of high grade lymphomas should be based on the accurate evaluation of the neoplastic extension.

Gastric MALT lymphoma: from aetiology to treatment

The development of gastric mucosa-associated lymphoid tissue (MALT) lymphoma is dependent on Helicobacter pylori infection. Bacterial colonisation of the gastric mucosa triggers lymphoid infiltration and the formation of acquired MALT. The bacterial infection induces and sustains an actively proliferating B-cell population through direct (autoantigen) and indirect (intratumoral T cells specific for H. pylori) immunological stimulation. Moreover, the bacterial infection provokes a neutrophilic response, which causes the release of oxygen free radicals. These reactive species may promote the acquisition of genetic abnormalities and malignant transformation of reactive B cells. A transformed clone carrying the translocation t(1;18)(q21;q21) forms a MALT lymphoma, the growth of which is independent of H. pylori and will not respond to bacterial eradication. Malignant clones without t(11;18)(q21;q21), but with other genetic abnormalities, such as trisomy 3 or microsatellite instability, depend critically on immune stimulation mediated by H. pylori for their clonal expansion. In the early stages, the tumour can be successfully treated by eradication of the bacterium, whereas at later stages the tumour may escape its growth dependency through acquisition of additional genetic abnormalities such as t(1;14)(p22;q32) and t(1;2)(p22,p12) involving the BCL-10 gene. Finally, further genetic abnormalities, such as inactivation of the tumour suppressor genes, p53 and p16, can lead to high-grade transformation. Detection of these abnormalities may help with the clinical management of patients with gastric MALT lymphoma.

MALT Lymphomas

This review addresses the biology and the treatment of lymphomas arising from mucosa-associated lymphoid tissue (MALT). This entity, first described in 1983, represents about 8% of all non-Hodgkin's lymphomas and was recently re-classified as "extranodal marginal zone lymphomas of MALT-type." The term marginal zone lymphoma (MZL) encompasses the three closely related lymphoma subtypes of nodal, primary splenic and extranodal lymphomas of MALT type: the latter represent the vast majority of MZL. These lymphomas arise at different anatomic sites, are composed of mature B-cells lacking expression of CD5 and CD10, often present with overlapping morphologic features, but typically quite distinct clinical behaviors. Only very recently cytogenetic/molecular genetic observations have underlined the distinctiveness of these three lymphoid neoplasms, which in both the R.E.A.L. and WHO-classifications are included in the general term of MZL. MALT lymphomas arise in numerous extranodal sites, but gastric MALT lymphoma is the most common and best studied and is, therefore, the paradigm for the group as a whole. Dr. Isaacson describes the principal histological features of these lymphomas, including criteria to distinguish this entity from other small B-cell lymphomas. Several lines of evidence suggest that gastric lymphoma arises from MALT acquired as the result of aH. pyloriinfection. However, at least 1/3 of cases do not respond to eradication ofH. pylori. Very recent data suggest that both t(11;18) (q21;q21) and bcl10 nuclear expression are associated with failure to respond to this treatment. Dr. Gascoyne discusses the biologic function of proteins deregulated through the different translocations, which play a role in pathogenesis of MALT lymphomas, emphasizing particularly their influence in disrupting the apoptotic pathway. Dr. Zucca reviews findings suggesting that MALT lymphoma is an antigen driven neoplasm. He also presents specific guidelines for treatment of gastric lymphomas trying to shed some light on the amazingly inconsistent and confusing data in the literature. Taking advantage on the more than 300 non-gastric MALT lymphomas collected by the International Extranodal Lymphoma Study Group (ILESG), Dr. Cavalli compares gastric lymphomas with those arising in many other sites. Overall, the data presented in this session will underline the fact, that MALT lymphomas are characterized by some unique biological properties.