Non-gastric Mucosa-associated Lymphoid Tissue Lymphoma Research Articles

Association of Treatment Disparities and Primary Sites with the Survival of Non-Gastric Early-Stage MALT Lymphoma

To investigate the association between utilization of radiotherapy and differences in survival among patients with non-gastric early-stage mucosa-associated lymphoid tissue (MALT) lymphoma at different primary sites. A total of 5,995 patients with non-gastric early-stage MALT lymphoma in the Surveillance, Epidemiology, and End Results (SEER) database treated between 2000-2015 were extracted and analyzed. Mediation analyses were conducted to quantitatively determine the proportion of the relationship between OS and primary sites mediated by radiotherapy. Inverse probability of treatment weighting (IPTW) was conducted to control confounding factors affecting treatment choice. After controlling for confounding factors, pulmonary MALT lymphoma was found to have the highest rate of omitted radiotherapy compared to other primary sites, including ocular adnexa, salivary gland, skin and other sites. Multivariate Cox analyses showed that lung MALT lymphoma patients had the lowest 10-year OS rate of 58.3%, while skin MALT lymphoma patients had the highest 10-year OS rate of 81.6%. After balancing confounding factors that potentially affected the choice of radiotherapy using IPTW, differences in utilization of radiotherapy explained a significant portion of the poor prognosis of lung MALT lymphoma (35.6%, P = 0.002) and the favorable prognosis of skin MALT lymphoma (6.1%, P <0.001). Differences in survival among patients with non-gastric early-stage MALT lymphoma at different primary sites are associated with disparities in the utilization of radiotherapy.

Radiotherapy for non-gastric intestinal versus gastric MALT lymphoma: a comparison of treatment outcomes.

BackgroundRadiotherapy is often used for treating patients with gastric mucosa-associated lymphoid tissue (MALT) lymphomas who fail to respond to Helicobacter pylori eradication. However, non-gastric intestinal MALT lymphoma is rare, and no standard therapeutic strategies have been established. This study was designed to assess the long-term prognosis of non-gastric intestinal MALT lymphoma treated with radiotherapy and to compare the outcomes with that of post-radiotherapy gastric MALT lymphoma.MethodsThe study included 34 patients with stage I EA gastrointestinal MALT lymphoma according to the Ann Arbor classification who underwent definitive radiotherapy. The primary site was the rectum in 3, the duodenum in 1, and the stomach in 30 patients. The radiotherapy dose was 1.5‒2.0 Gy (median, 1.5 Gy) and the total dose was 30‒40 Gy (median, 30 Gy). The clinical target volume (CTV) was defined as the volume of the entire organ with the lymphoma. Adjacent lymph node areas were not routinely included in the CTV.ResultsComplete response (CR) was achieved in all patients. There were no local recurrences, and two cases of recurrence were observed at other sites. The 5-year overall survival rates for non-gastric and gastric MALT lymphomas were 100% and 94.7%, respectively, and the 5-year disease-free survival rates were 100% and 95.7%, respectively. None of the patients died of the current illness.ConclusionRadiotherapy for non-gastric intestinal MALT lymphoma is expected to result in good local control and long-term survival, similar to that for gastric MALT lymphoma.

A Case of Mucosa-Associated Lymphoid Tissue Lymphoma in Nasopharynx and Thyroid Gland

Mucosa associated lymphoid tissue (MALT) lymphoma refers to a type of marginal zone lymphomas, which represent a group of non-Hodgkin lymphomas originated from B lymphocytes of marginal zone. They are classified as extranodal MALT type (MALT lymphoma), splenic marginal zone B-cell lymphoma and nodal marginal zone B-cell lymphoma according to clinical and therapeutic implications of the tumor. MALT lymphoma is the most common type of marginal zone lymphoma, and about 5-8% of all B-cell lymphomas are diagnosed as MALT lymphoma. MALT lymphomas are usually found in the gastrointestinal tract, mostly in the stomach associated with H pylori infection; the non-gastric MALT lymphoma can also be found in the salivary gland, lung, head and neck, ocular adnexa, skin, thyroid, or breast. However, the involvement of nasal cavity and nasopharynx is rare. Based on our recent experience and a review of related literature, we report a case of MALT lymphoma that occurred in the nasopharynx and thyroid gland, which were treated with localized radiotherapy. Key words: Mucosa-associated lymphoid tissue lymphoma ㆍ Nasopharynx ㆍ Thyroid gland

A 54-Year-Old Man Referred With Nonresolving Pneumonia

A 54-year-old man was referred with nonresolving pneumonia. He had been treated for community-acquired pneumonia 6 weeks earlier. He reported grade 2 dyspnea, malaise, and a nonproductive cough. He had also experienced three episodes of minimal hemoptysis but denied weight loss, fever, or any other constitutional symptoms. He was a nonsmoker and was being treated for dyslipidemia.

Primary Colonic MALT Lymphoma: A Very Rare Cause of Iron Deficiency Anemia

Purpose: MALT lymphoma involves the colon less than 20% of the time. This is mostly in a secondary fashion, and less than 5% of primary colonic lymphomas are of the MALT subtype. This amounts to less than 0.1% of all colorectal malignancies. A 53-year-old woman with diabetes, hypertension, and CHF presented for colonoscopy to further evaluate iron deficiency anemia. She was asymptomatic, specifically denying melena or hematochezia. Family history was negative for colorectal polyps or cancer. The abdomen was soft, with no palpable masses. Colonoscopy revealed a 7 x 5-cm round, firm, submucosal, friable mass at the hepatic flexure. It occupied the entire lumen, but was able to be traversed. Biopsies were consistent with marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT). CT showed invasion of the adjacent adipose tissue with regional lymphadenopathy. EGD showed mild H. pylori-positive gastritis and duodenitis, but there were no findings to indicate gastric MALT, and she was treated with antibiotics. Bone marrow biopsy showed malignant lymphoma invasion. R-CHOP was initiated for disseminated disease, but held after two cycles due to decompensated CHF. Follow-up PET scan revealed no activity in the hepatic flexure, and she will have a colonoscopy and CT scan for surveillance. The location of the lesion in the hepatic flexure in our case is consistent with the reported mild-to-moderate predilection for the proximal colon. One quarter to one third of non-gastric MALT lymphomas are disseminated at diagnosis. More than 80% of patients with intestinal MALT present with symptoms referable to the GI tract, but despite the large size of the tumor, our patient was asymptomatic and already had signs of invasion. Regardless of treatment modality or stage at diagnosis, the disease typically follows an indolent course with excellent 5-year survival rates of 85-100%. However, the relapse rate in non-gastric MALT lymphoma approaches 50%, emphasizing the need for lifelong follow-up in these patients.Figure

Analyses of clinical features and outcomes of 57 patients with non-gastric MALT lymphoma

To further understand the clinical features of non-gastric mucosa-associated lymphoid tissue (MALT) lymphoma and investigate its suitable treatment. A retrospective survey of 57 non-gastric MATL lymphoma patients pathologically confirmed in our hospital from 1999 to 2011. The median age was 58 years (range 14-86 years). Common presenting sites of non-gastric MALT lymphoma included lungs and upper respiratory tract (17 patients, 29.8%), intestinal tracts (16 patients,28.1%), orbital and ocular adnexal (7 patients, 12.3%), and salivary glands (8 patients, 14.0%). Stage Ⅰ-Ⅱdisease presented in 35 patients (61.4%), stage Ⅲ-Ⅳ disease in 22 patients (38.6%). A total of 26 patients had nodal involvement and 7 patients multiple organ involvement. Regimens included surgery alone, chemotherapy alone, surgery followed by chemotherapy or chemoradiotherapy. The complete response (CR) rate was 66.0% and the overall response rate 85.7%. At a median follow-up of 52 months, the 5-year overall survival (OS) and the 5-year progression free survival (PFS) were 91.6% and 77.7%, respectively. The 5-year survival rate of surgery, chemotherapy, surgery+chemotherapy, surgery + chemotherapy + radiotherapy groups were 87.5%, 100.0%, 90.2% and 100.0%, respectively, without significant differences. The 5-year PFS of the four groups were 62.3%, 80.0%, 90.2% and 75.0% respectively. Non-gastric MALT lymphoma is characterized by disseminated onset, favorable response to treatments and good outcomes. There is no statistically significant difference in the overall survival of the various treatments. But the recurrence rate of surgery alone is relatively high (22.3%).

1075P - Detection of Caga Expression in Gastric Mucosa-Associated Lymphoid Tissue Lymphoma—Biologic Significance and Clinical Implication

ABSTRACT Background We recently reported that a direct contact of Helicobacter pylori (HP) with B cells resulted in CagA translocation into the cells (Cancer Res 2010;70:5740-8). The translocated CagA further activates extracellular signal-regulated kinase (ERK) and p38 mitogen-activated protein kinase (MAPK), and up-regulates the expressions of Bcl-2 and Bcl-xL. In this study, we sought to verify if CagA exists in the malignant B cells of gastric mucosa-associated lymphoid tissue (MALT) lymphoma. Methods Expression of CagA protein, phospho-SHP-2, phospho-ERK, phospho-p38MAPK, Bcl-2 and Bcl-xL in a series of 26 gastric MALT lymphoma was determined by immunohistochemistry. Western blot analysis was done to confirm immunohistochemical detection of CagA and biopsies from non-gastric MALT lymphoma served as negative controls. The association of CagA expression and the tumor response to HP-eradication (HPE) therapy was evaluated in 77 stage IE/IIE1 low-grade gastric MALT lymphoma patients. Results The expression of CagA was detected in 35 (45.5%) of 77 patients. CagA expression was closely associated with the expression phospho-SHP-2 (P = .016), phospho-ERK (P Conclusion CagA protein can be translocated into malignant B cells of MALT lymphoma. The expression of CagA in lymphoma cells appears to be biologically and clinically significant. Disclosure All authors have declared no conflicts of interest.

Primary mucosa-associated lymphoid tissue lymphoma of Waldeyer's ring:clinical characteristics and long-term outcome

Objective To investigate the clinical characteristics and long-term outcome of patients with mucosa-associated lymphoid tissue ( MALT) lymphoma of Waldeyer's ring. Methods Ten patients were retrospectively analyzed. Seven patients had stage ⅠE and 3 patients had stage ⅡE disease. All patients received radiation therapy with a median dose of 40 Gy, and 7 patients also received 1 t0 4 cycles of CHOP-based chemotherapy before radiation. Results The ratio of male to female was 1∶9. The median age was 58 years. No patient had B symptoms. One patient had elevated LDH level. The complete response rate after treatment was 100％. With median follow-up periods of 90 months, 1 patient died from rectal cancer. One patient developed brain metastasis and was salvaged by radiotherapy. The 5-year overall survival, cancer specific survival and progression-free survival rates were 90％ , 100％ and 80％ , respectively. Conclusions The clinical characteristics of Waldeyer's ring MALT lymphoma were similar to that of nongastric MALT lymphoma. For patients with Waldeyer's ring MALT lymphoma, primary radiotherapy can result in excellent long-term survival. Key words: Lymphoma / radiotherapy; Lymphoma,mucosa - associated lymphoid tissue; Lymphoma,Waldeyer' s ring; Prognosis

Recent Developments in Nongastric Mucosa-Associated Lymphoid Tissue Lymphoma

Guidelines and algorithms for the management of gastric mucosa-associated lymphoid tissue (MALT) lymphoma have been developed in the recent past, but the situation regarding nongastric MALT lymphomas is much more complicated. Owing to the heterogeneity of MALT lymphomas arising in various organs, different approaches to treatment have been applied, mostly in an uncontrolled fashion. In the recent past, for example, attempts to use antibiotic therapy in managing ocular adnexal MALT lymphomas have been reported, with response rates varying between 0% and 60% with the use of doxycycline or, more rarely, clarithromycin. Currently, antibiotic therapy remains experimental, with conflicting data and apparent geographic variations. In addition, there is no clear consensus whether radiation or systemic therapy is more effective in MALT lymphomas at different locations, including the lung and the ocular adnexa. This review highlights and briefly discusses some recent developments in the management of nongastric MALT lymphomas.

Treatment outcome of 40 patients with early stage nongastric mucosa-associated lymphoid tissue lymphoma

Objective To analyze the clinical features and prognosis of patients with stage Ⅰ_E/Ⅱ_Enongastric mucosa-associated lymphoid tissue (MALT) lymphoma. Methods Between 2000 and 2006, 40 patients with previously untreated nongrastric MALT lymphoma were retrospectively reviewed. The primary site of lymphoma was the intestinal tract in 10 patients, the orbit in 9, the thyroid in 8, the lung in 5, the Waldeyer ring in 2, and the others organs in6. At diagnosis, 27 patients had stage Ⅰ_E, and 13 had stage Ⅱ_E disease. Seventeen patients were treated with radiotherapy with or without chemotherapy, 18 with chemotherapy without radiotherapy, and 5 with surgery alone. The median age was 54 years. The ratio of male to female was 2: 1. Results With a median follow-up of 58 months, the estimated 5-year overall survival (OS) rate and progression-free survival (PFS) rate were 86% and 82%, respectively. The 5-year OS and PFS rates were 92% and 85% for stage Ⅰ_E, 76% and 82% for stage Ⅱ_E disease, respectively (χ~2 =3.66,P =0. 060;χ~2 =1.04,P=0. 300). The 5-year OS and PFS rates were both 100% for patients with MALT lymphoma of the orbit and ocular adnexa. None of the 17 patients with radiotherapy had locoregional relapse, whereas 3 of 23 (13%) patients without radiotherapy had locoregional relapse. Conclusions Patients with stage Ⅰ_E nongastric MALT lymphoma have a favorable prognosis. Radiotherapy is still a standard care for early stage disease. The treatment outcome of patients with MALT lymphoma of the orbit and ocular adnexa is even better. Key words: Lymphoma, nongrastic mucosa-associated lymphoid tissue/radiotherapy; Lymphoma, nongrastic mucosa-associated lymphoid tissue/chemotherapy; Prognosis

More than a third of non‐gastric malt lymphomas are disseminated at diagnosis: a single center survey

Mucosa-associated lymphoid tissue (MALT) lymphomas are extranodal B-cell tumors that generally follow an indolent course. The gastrointestinal tract is the most common site of MALT lymphoma, comprising 50% of all cases. The tissue lesions are often localized, have high therapeutic response rates with late relapses with a long overall survival (OS). The patients with non-gastric lesions may follow a different clinical course and many of them present with disseminated disease. This study reports a series of 51 patients with non-gastric MALT lymphoma. Twenty patients (39.2%) presented with disseminated disease, seven (13.7%) patients had two MALT mucosal sites involved and eight (15.7%) had involvement of three or more mucosal sites. At presentation, 17 (33.3%) patients had the lymph node and 12 (23.5%) the bone marrow involvement. Following various combinations of treatment, complete remission was achieved in 40 (81.6%), and partial remission in three of the 49 treated patients with no difference in response rates between different disease stages. Relapse occurred in 12/43 (27.9%) patients among whom eight (18.6%) recurred in the presenting organ system. Five patients (9.8%) died because of a rapid disease progression after a median follow-up of 56 months; two patients with primary lung lesions, 1 patient with secondary intestinal disease, and 2 patients suffered transformation to diffuse large B-cell lymphoma. No significant difference in survival was found between localized and disseminated disease (log rank 0.05, df = 1, P = 0.81). A patient age > or = 60 yr at diagnosis and presentation with the nodal disease were found to be statistically significant negative prognostic factors (P < 0.05). Median OS was not reached after 145 months of follow-up, with the estimated OS being 88% at 2 yr, and 78% at 5 yr.

Mucosa-associated lymphoid tissue lymphoma studied with FDG-PET: a comparison with CT and endoscopic findings

We investigated the accumulation of 2-deoxy-2-[(18)F] fluoro-D: -glucose positron emission tomography (FDG-PET) in patients with mucosa-associated lymphoid tissue (MALT) lymphoma patients as compared with computerized tomography (CT) and endoscopic imaging. FDG-PET was performed on 13 untreated patients with MALT lymphoma. CT scanning of the affected areas was performed in all the patients to compare with the FDG-PET images. In five patients with gastric MALT lymphoma, comparison was also made with the endoscopic findings. Of the 13 untreated MALT lymphoma patients, all 8 non-gastric MALT lymphoma patients exhibited abnormal accumulation of FDG. However, in the five gastric MALT lymphoma patients, no abnormal FDG accumulation was observed. Although lesions could be confirmed on CT images from the patients other than those with gastric MALT lymphoma, the mucosal lesions of gastric MALT lymphoma could be observed only by endoscopy. FDG-PET can be used to detect MALT lymphoma when it forms mass lesions, whereas it is difficult to detect non-massive MALT lymphoma of gastrointestinal origin.

Dissemination patterns in non-gastric MALT lymphoma

In contrast to gastric extranodal marginal zone mucosa associated lymphoid tissue (MALT) lymphomas, there is little consensus on the value and clinical consequences of extensive staging at diagnosis and during follow-up in non-gastric MALT lymphomas. Complete clinical information at presentation and during follow-up was collected for 72 patients with non-gastric MALT lymphoma treated at the Netherlands Cancer Institute between 1977 and 2005. Dissemination patterns at presentation were studied for nine primary dominant organ groups in our series of 72 patients and in a similar cohort treated at Vienna University (for a total of 106 patients). Twenty-three of our patients (32%) had more than one site of extranodal MALT lymphomatous disease, 13 patients (18%) had regional nodal involvement and 7 (10%) had bone marrow involvement. Site-specific dissemination was seen in paired organs (orbit, lung) and in the gastrointestinal tract (stomach, colon) and primary pulmonary MALT lymphoma was specifically related to gastric involvement (p<0.0001). These patterns of dissemination were retained during relapsed disease. Primary extranodal non-gastric marginal zone MALT lymphoma frequently presents as stage IV disease (26%) and multifocal disease (32%) and with a site-specific dissemination pattern. After an extensive staging procedure at presentation, we recommend primary site-directed protocols during follow-up focused on the primary involved tract/organ system, regional lymph nodes and pulmonary and gastric relapses.

Low-Grade Non-Hodgkin Lymphomas

The most common low-grade non-Hodgkin lymphomas are of B-cell origin. This review will focus on follicular lymphomas and extranodal marginal zone lymphomas, also known as mucosa-associated lymphoid tissue (MALT) lymphomas. These are radiation-sensitive lymphomas. Moderate doses (30-35 Gy) for these stage I and II low-grade lymphomas result in long-term local control and possible cure. Involved-field radiation therapy is the standard approach and produces minimal morbidity. However, 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 nongastric MALT lymphoma 30% to 40% after 10 years. Patients with relapsed disease are not curable with chemotherapy, but the disease often remains indolent and prolonged survival is observed. For gastric MALT lymphomas associated with Helicobacter pylori but which did not respond to antibiotic therapy, radiation treatment is indicated and almost always curative. For localized MALT lymphomas not related to microorganisms, radiation therapy is the initial standard therapy regardless of anatomic location. Patients with stage III and IV low-grade lymphoma and local symptoms are often successfully palliated with a low dose regimen of 2 x 2 Gy (total dose 4 Gy).

Risk of Second Cancer in Nongastric Marginal Zone B-Cell Lymphomas of Mucosa-Associated Lymphoid Tissue: A Population-Based Study from Northern Italy

The aim of this study was to define the risk of second cancer in nongastric marginal zone lymphomas of mucosa-associated lymphoid tissue (MALT). We considered for the analysis 157 patients with a confirmed histology of marginal zone B-cell lymphoma of MALT, presenting with a clinically prevalent extranodal site of disease, except for stomach. All patients came from two hematologic institutions of Northern Italy. We compared the occurrence of second cancer with respect to the general population by calculating the standardized incidence ratio, with the age- and sex-specific incidence rates of a cancer registry of Northern Italy (Lombardia) as a reference. A history of solid neoplasia was present in 29 (18%) patients for a total number of 30 neoplasms: 25 solid tumors, 2 hematologic diseases (1 Hodgkin's lymphoma and 1 essential thrombocythemia), and 3 nonmelanoma in situ skin cancers. In 4 patients, the site of cancer and lymphoma was the same. In 21 cases the solid tumor preceded the MALToma, in 3 the neoplasm was concomitant, whereas in 6 it was subsequent. For the entire group, the standardized incidence ratio of an additional malignancy was 0.8 [95% confidence interval (95% CI), 0.55-1.17; P = 0.2]. After excluding nonmelanoma skin cancer, the standardized incidence ratio of a second tumor was 0.75 (95% CI, 0.5-1.12; P = 0.2). After excluding all previous malignancies, the standardized incidence ratio of a second cancer was 1.32 (95% CI, 0.69-2.55; P = 0.4). The comparison of risks between males and females was not significant in each group analysis. Patients with nongastric MALT lymphomas are not at increased risk for other neoplasms compared with the general population of the same geographic area.

Non-Hodgkin's Lymphoma of Mucosa-Associated Lymphoid Tissue

The concept of mucosa-associated lymphoid tissue (MALT) lymphomas was introduced by Isaacson and Wright [Cancer 1983; 52:1410-1416] in 1983. After more than 20 years of clinical research MALT lymphomas are now recognized as a distinct subtype of non-Hodgkin's lymphoma (NHL) with unique pathogenic, histological, and clinical features. Although this subtype of NHL occurs frequently, optimal management remains elusive. This manuscript reviews features of the clinical presentation, diagnosis, pathology, molecular characteristics, and management of both gastric and non-gastric MALT lymphoma.

Association between Chlamydia psittaci infection and extranodal marginal zone B-cell lymphoma of mucosa associated lymphoid tissue (MALT)-lymphomas

7568 Background: MALT-lymphomas are often associated with infectious organisms. Microbial species associated with MALT lymphomas are: Helicobacter pylori (H.pylori), Campylobacter jejuni, Borrelia burgdorferi, and Hepatitis C Virus. Recent studies showed evidence of Chlamydia psittaci (C. psittaci) infection in 80% of ocular adnexal lymphoma and tumor regression following eradication therapy. We studied the presence of C. trachomatis, C. pneumoniae, and C. psittaci DNAs in MALT lymphomas of various sites and in non-malignant controls. Methods: MALT lymphomas from the following sites were selected for analysis: salivary gland (n=13), thyroid gland (n=4), skin (n=2), ocular adnexa (n=2), stomach (n=6), intestinum (n=4). Samples of Sjoegren syndrome (n=10) and samples of H. pylori positive gastritis (n=7) were included as non-malignant controls. Macrodissected tissue containing &gt;80% lymphoma cells from paraffin embedded tissue was processed for DNA isolation. For the presence of C. psittaci and C. pneumoniae DNA real time PCR assays were used. For C. trachomatis a commercially available PCR assay (Roche Molecular Diagnostics) was employed. All samples were tested twice. A sample was regarded as positive if at least one positive result was obtained. Results: C. psittaci was found at variable frequencies in MALT lymphomas of different sites: 4/13 (31%) salivary gland, 2/4 (50%) thyroid gland, 2/2 (100%) skin, 2/2 (100%) ocular adnexa, 1/6 (17%) gastric, and 0/4 intestinal MALT lymphomas. Among the non-malignant specimens, C. psittaci DNA was detected in 4/10 (40%) samples of Sjoegren syndrome and in 0/7 samples of H. pylori positive gastritis. All nongastric MALT lymphomas tested were negative for C. trachomatis and C. pneumoniae. Conclusion: Our data reveal a clear association of C. psittaci infection with extragastric MALT lymphoma. However, no evidence could be established for C. trachomatis and C. pneumoniae infection. Moreover, the high prevalence of Sjoegren syndromes - the most frequent precursor lesion for MALT lymphomas of salivary gland and ocular adnexa - may suggest an involvement of C. psittaci induced antigenic driven lymphomagenesis in a significant proportion of extragastric MALT lymphomas. No significant financial relationships to disclose.

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.

Radiological features of non-gastric mucosa-associated lymphoid tissue lymphomas

The term marginal zone lymphoma encompasses the three closely related lymphoma subtypes of nodal, primary splenic, and extranodal lymphomas of mucosa-associated lymphoid tissue (MALT). The latter were first described by Isaacson and Wright, who demonstrated that these MALT lymphomas have both different sites and clinical and histologic characteristics compared with marginal zone, nodal B-cell lymphomas. 1 Some years later, MALT lymphomas were accepted as an independent category of lymphoma and were defined as extranodal marginal zone B-cell lymphomas of MALT type in the revised European‐ American Classification of Lymphoid neoplasms (REAL classification), 2 as well as in the more recent classification proposed by the World Health Organization (WHO). 3

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.