Mucosa-associated lymphoid tissue lymphoma

Current Status of the Spectrum and Therapeutics of Helicobacter pylori-Negative Mucosa-Associated Lymphoid Tissue Lymphoma

Helicobacter pylori (HP)-unrelated mucosa-associated lymphoid tissue (MALT) lymphoma includes the majority of extragastric MALT lymphomas and a small proportion of gastric MALT lymphomas. Although the role of first-line antibiotics in treating HP-negative gastric MALT lymphomas remains controversial, HP eradication therapy (HPE)-like regimens may result in approximately 20-30% complete remission (CR) for patients with localized HP-negative gastric MALT lymphoma. In these patients, H. heilmannii, H. bizzozeronii, and H. suis were detected in sporadic gastric biopsy specimens. Extragastric MALT lymphoma is conventionally treated with radiotherapy for localized disease and systemic chemotherapy for advanced and metastatic diseases. However, a proportion of extragastric MALT lymphomas, such as ocular adnexal lesions and small intestinal lesions, were reported to be controlled by antibiotics for Chlamydophila psittaci and Campylobacter jejuni, respectively. Some extragastric MALT lymphomas may even respond to first-line HPE. These findings suggest that some antibiotic-responsive tumors may exist in the family of HP-negative MALT lymphomas. Two mechanisms underlying the antibiotic responsiveness of HP-negative MALT lymphoma have been proposed. First, an HPE-like regimen may eradicate the antigens of unknown bacteria. Second, clarithromycin (the main component of HPE) may have direct or indirect antineoplastic effects, thus contributing to the CR of these tumors. For antibiotic-unresponsive HP-negative MALT lymphoma, high-dose macrolides and immunomodulatory drugs, such as thalidomide and lenalidomide, have reported sporadic success. Further investigation of new treatment regimens is warranted.

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

BALToma masquerading as pulmonary tuberculosis

A 53-year-old man with a significant smoking history presented with chronic cough, exertional breathlessness, intermittent fever, weight loss and anorexia. A review of his past medical records revealed he was diagnosed to have sputum smear-positive pulmonary tuberculosis 5 years earlier, for which he had received multiple courses of incomplete antitubercular therapy. This time, though he was primarily suspected to have active pulmonary tuberculosis, lack of microbiological evidence and further investigations including histopathological evaluation of lung lesions confirmed a diagnosis of Marginal zone B cell lymphoma of mucosa-associated lymphoid tissue (MALToma/BALToma). The patient was managed with radical radiation therapy to which he responded well.

Gastric biopsies: the gap between evidence-based medicine and daily practice in the management of gastric Helicobacter pylori infection

BACKGROUND

Many consider histology to be the gold standard for Helicobacter pylori detection. Because the number and distribution of H pylori organisms vary, particularly in patients taking proton pump inhibitors (PPIs), the American Gastroenterological Association recommends discontinuing PPIs two weeks before endoscopy, and taking biopsies from both the body and antrum.

OBJECTIVE

To assess the influence of clinical practice on the histopathological detection of H pylori infection.

METHODS

Electronic patient records were evaluated for the sites of gastric sampling and PPI use at endoscopy. One hundred fifty cases with biopsies taken from both antrum and body were randomly selected for pathological re-review with special stains. The gastric regions sampled, H pylori distribution and influence of clinical factors on pathological interpretation were assessed.

RESULTS

Between 2005 and 2010, 10,268 biopsies were taken to detect H pylori. Only one region was sampled in 60% of patients (antrum 47%, body 13%). Re-review of biopsies taken from both antrum and body indicated that the correct regions were sampled in only 85 (57%) patients. Of these, 54 were H pylori positive and 96 were H pylori negative. H pylori was present in the antrum in only 15% of the patients and body only in 21%. Of 96 H pylori-negative patients, two were reinterpreted as positive. Forty-seven per cent of patients were taking PPIs at endoscopy, contributing to both false-negative and false-positive diagnoses.

CONCLUSION

Despite national and international guidelines for managing H pylori infection, the American Gastroenterological Association guidelines are infrequently adhered to, with PPIs frequently contributing to false diagnosis; sampling one region only increases the likelihood of missing active infection by at least 15%.

[MALT-type parotid lymphoma--a case report and the review of the literature]

Primary lymphomas of the salivary glands are rare. It is estimated that they constitute no more than 5% of all lymphomas in different locations. The most common subtype developing in parotid glands is marginal zone B-cell mucosa associated lymphoid tissue type lymphoma (MALT) that belongs to a group of low-grade tumours. There are many factors associated with the incidence of that proliferative process: environmental and infectious agents as well as immune deficiency states. We describe a case of primary non-Hodgkin's lymphoma of the parotid gland arising in the background of previously undiagnosed and untreated Sjögren's syndrome in a 52-year-old woman. The article concerns a short review of the literature regarding etiology, symptoms, treatment and survival prognosis in that rare disease as well. MALT lymphomas should always be considered in the differential diagnosis of the tumors and swelling of the parotid gland area. A special, regular monitoring should include all patients with Sjögren's syndrome as those with the proven greater risk of developing that proliferative disease. The role of the laryngologist in the case of MALT-type lymphoma of the parotid gland should focus on a diagnosis and possible tumor cytoreduction with maximal saving of the facial nerve. The essential treatment of this pathology is one of the oncologists and haematologists.

Review article: common misconceptions in the management of Helicobacter pylori-associated gastric MALT-lymphoma

BACKGROUND

Helicobacter pylori infection is the main cause of gastric mucosa-associated lymphoid tissue (MALT) lymphoma.

AIM

To review several common misconceptions in the management of H. pylori-associated gastric MALT-lymphoma.

METHODS

Bibliographical searches were performed in MEDLINE up to June 2011.

RESULTS

If adequate diagnostic methods are used, and if only low-grade lymphomas are considered, the prevalence of H. pylori infection is very high (almost 90%). H. pylori eradication is effective in treating approximately 80% of patients with early stage lymphoma. In H. pylori-positive gastric high-grade lymphomas, antibiotic therapy should always be prescribed, as approximately 50% of them regress after H. pylori eradication. Patients with early stage MALT lymphoma negative for H. pylori might still benefit from antibiotic treatment as the sole treatment. Complete remission of gastric MALT lymphoma after H. pylori eradication can take even >12 months. PCR assay for the detection of monoclonal B cells remains positive in many cases after complete remission has been reached. Patients with a persistent clonal band should not be treated unless the lymphoma can be histologically demonstrated. Synchronous occurrence of gastric adenocarcinoma and MALT lymphoma has been repeatedly reported. In some patients in complete remission, eradication of H. pylori does not prevent later development of early gastric cancer. Gastric lymphoma recurrence occurs in some patients after both bacterial and lymphoma regression. H. pylori reinfection does not constitute a prerequisite for lymphoma recurrence.

CONCLUSIONS

The present article states several misconceptions in the management of H. pylori-associated gastric MALT-lymphoma in clinical practice, reviews the related scientific evidence and proposes the adequate attitude in each case.

Marginal zone lymphomas with plasmacytic differentiation and related disorders

Marginal zone lymphomas of all types (nodal, splenic, and extranodal mucosa-associated lymphoid tissue [MALT]) may show plasmacytic differentiation. Distinguishing marginal zone lymphomas from other small B-cell lymphomas with plasmacytic differentiation, especially lymphoplasmacytic lymphoma, or from plasma cell neoplasms may be challenging. Marginal zone lymphomas with plasmacytic differentiation were discussed in 2 sessions of the 2009 Society for Hematopathology/European Association for Haematopathology Workshop. Session 4 focused on nodal marginal zone lymphomas, including cases exhibiting classic features and cases displaying atypical phenotypes. The difficulties of classification of cases with increased numbers of large cells were also discussed. Session 5 examined nonnodal marginal zone lymphomas and related entities, including splenic marginal zone lymphoma, MALT lymphoma, γ heavy chain disease, and cryoglobulin-associated lymphoproliferative disorders. These cases illustrate the importance of clinical data and, in some cases, phenotypic and cytogenetic findings in appropriately applying the 2008 World Health Organization criteria.

Higher rates of t(11;18) in Chinese patients with transformed type of MALT lymphoma suggest novel pathways for progression of the disease

To detect the t(11;18) chromosome translocation in different stages of mucosa-associated lymphoid tissue (MALT) lymphoma, we established a RT-PCR method by adopting three new primer pairs and using the RNA extracted from the paraffin tissues to amplify the t(11;18) fusion gene API2-MALT1 in shorter lengths. Our results showed five key findings, which are (a) higher detection rates of t(11;18) (21.13%) in Chinese patients with transformed MALT lymphoma, (b) lower detection rates of t(11;18) in stomach MALT lymphoma, (c) different organ localizations of MALT lymphoma in Chinese patients, (d) higher nuclear expression rates of Bcl-10 in low grade MALT (51.72%), and (e) lower response rates (50% CR, and 50% PR) to anti-H.-pylori therapy. These findings suggest novel pathways for low-grade MALT lymphoma to be progressed into transformed MALT lymphoma. This study also suggests that amplification of shorter length of PCR products from the paraffin-fixed tissues increases sensitivity, which is significant in improving the selection of the therapeutic regimen and assessing the prognosis of the disease.

Chromosomal instability in gastric mucosa-associated lymphoid tissue lymphomas: a fluorescent in situ hybridization study using a tissue microarray approach

Extranodal marginal zone B-cell lymphomas (mucosa-associated lymphoid tissue [MALT] lymphomas) of the gastrointestinal tract have been known to have characteristic chromosomal aberrations including trisomies of chromosomes 3, 12, and 18. However, knowledge of the clinical significance of cytogenetic changes in MALT lymphomas is still limited. In the present study, the frequency of the numeric and structural aberrations of the chromosomes 1, 3, 12, 18 and X and of the MALT1 gene as well as their potential clinical significance were analyzed by using fluorescent in situ hybridization on a tissue microarray containing 257 tissue samples from 203 cases of surgically resected primary gastric lymphomas including 115 cases of MALT lymphomas, 88 cases of diffuse large B-cell lymphomas (DLBCLs, 75 with an associated MALT lymphoma, so-called ex-MALT DLBCL, and 13 de novo), and 54 controls cases of Helicobacter pylori-associated chronic gastritis. Clinical follow-up information was available in 137 cases. Trisomies 1, 3, 12, and 18 were detected in 3.3%, 44.4%, 12.3%, and 19.2% of MALT lymphomas and in 11.1%, 42.2%, 26.5%, and 22.0% of ex-MALT DLBCLs, respectively. In addition, we found gains of the X chromosome in 36.4% of MALT lymphomas, in 34.5% of ex-MALT DLBCLs, and in 36.4% of de novo DLBCLs. Structural and/or numeric abnormalities of the MALT1 gene were observed in 37.0% of MALT lymphomas and in 22.2% of ex-MALT DLBCLs. In de novo DLBCL, trisomies for chromosomes 3, 12, 18, and X were found in 42.9%, 10.0%, 11.1%, and 36.4%, respectively, whereas alterations of MALT1 (namely, translocations) were found in 20.0% of the cases. An unexpected high and previously unreported gain of chromosome X in gastric MALT lymphomas was found. This tumor appears, therefore, to be a genetically unstable neoplasia. Our results point out that t(11;18) and aneuploidy may be both involved in lymphomagenesis and that at least a subset of MALT lymphomas may progress toward high-grade neoplasia.

Positron emission tomography of stage IV mucosa-associated lymphoid tissue lymphoma confined to the four major salivary glands

In a patient with stage IVA marginal zone lymphoma, (18)F-fluorodeoxyglucose-positron emission tomography indicated that the disease was confined to the four major salivary glands. The positron emission tomography findings encouraged the use of radiotherapy with curative intent in this case. After 30 Gy of external beam radiotherapy to the parotid and submandibular glands, the patient entered a complete remission and remains free from progression more than 4 years later.

MALT1, BCL10 and FOXP1 in salivary gland mucosa-associated lymphoid tissue lymphomas

In view of the certain anatomic site-dependent frequency of chromosomal translocations involved in extranodal marginal zone B cell lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma) pathogenesis, 17 salivary gland MALT lymphoma cases were analyzed for MALT1 and FOXP1 translocations. B cell CLL/lymphoma 10 (BCL10) and forkhead box PA (FOXP1) protein expression were studied by immunohistochemistry and translocations identified using fluorescence in situ hybridization (FISH)-specific probes FOXP1, t(11;18)(q21;q21)/API2-MALT1 and t(14;18)(q32;q21)/IgH-MALT1. None of the 11 analyzed cases showed FOXP1 rearrangement or amplification. The t(11;18) was present in five of 13 cases and the t(14;18) in three of 13 cases. MALT1 translocations were mostly mutually exclusive except in a single case. FOXP1 protein expression showed differences in the proportion of tumor cells with nuclear expression but not in their intensity, with the exception of one case where very intense nuclear staining was noted. BCL10 nuclear expression was present in four of 17 cases, two of which lacked t(11;18). Our results suggest that MALT1-specific translocations and FOXP1 rearrangements are not commonly involved in pathogenesis. A case with strong FOXP1 protein expression indicates the possibility that the upregulation of FOXP1 expression is significant in a small subset of salivary gland MALT lymphomas. Also a single case in which both MALT1 translocations were present indicates that these are not always mutually exclusive.

Primary extranodal lymphomas of gastrointestinal localizations: a single institution 5-yr experience

This study is aimed at comparison of patients with extranodal lymphomas based on pathohistological findings differences (MALT vs non-MALT) as well as regarding gastric and non-gastric localization, and determining the significance of clinical-laboratory parameters with respect to therapeutic response and length of survival. A total of 56 patients with extranodal non-Hodgkin's lymphomas of the gastrointestinal tract were evaluated over a 5-yr period. Regarding the localization of the disease, the stomach was most frequently affected, 39 patients (70%); followed by small and large intestines, 17 patients. As for the pathohistological findings, MALT lymphoma accounted for 70%, DLBCL 25%, while other subtypes accounted for 5%. Patients' distribution was analyzed according to CS based on both Ann Arbor and Lugano systems; however, the difference obtained between the groups was not statistically significant in both staging types of patients. Statistically significant difference in patients' distribution was not found with respect to IPI index, bone marrow infiltration, anemia, hypoalbuminemia, or histological subtype and localization. Difference in survival between patients according to the pathohistological type was not statistically significant also according to the type of the affected gastrointestinal tract organ. Statistical significance of difference according to survival probability was obtained based on age (survival is longer in patients over 55 yr of age); according to CS and according to Ann Arbor and Lugano classifications (the patients with lower CS live significantly longer); according to IPI index (the survival is significantly longer in patients with lower probability: IPI-0,1, and 2), as well as patients free of bone marrow infiltration whose survival is also significantly longer.

Molecular biology of lymphoma in the microarray era

This review will focus on the molecular biology of lymphoproliferative disorders with emphasis on lymphomas. The spectrum of known recurrent gene rearrangements found in lymphomas will be outlined and their relevance to diagnosis and subclassification of disease will be discussed. Finally, a survey of the current trends in gene expression profiling of lymphomas by microarray technology will be presented with reference to implications for diagnosis, classification, prognosis and treatment.

Epidemiology of non-Hodgkin lymphomas in Tyrol/Austria from 1991 to 2000

AIMS

To analyse the entity specific incidence and disease specific survival (DSS) of non-Hodgkin lymphomas (NHLs) in Tyrol/Austria, 1991-2000.

METHODS

Data from 1307 NHLs (excluding primary cutaneous lymphomas and monoclonal gammopathies of undetermined significance) were obtained. Current status was available for all patients. Except for 29 cases of small lymphocytic (CLL/SLL), lymphoblastic leukaemia (ALL), and myeloma (MM), which were diagnosed cytologically, diagnoses were reclassified on paraffin wax embedded archival material according to new World Health Organisation criteria. Sex specific age adjusted standardised incidence rates were computed using Segi's population weighting. Annual incidence changes were calculated by weighted least square regression analysis. Survival was estimated by the Kaplan-Meier method and compared by log rank test.

RESULTS

NHL more frequently affected men (male/female ratio, 1.52). Mean age of occurrence was 61 and 66 years for men and women, respectively. The incidence rate of 14.3 remained constant. There was a significant increase in diffuse large B cell lymphoma (DLBCL) and decrease in CLL/SLL in men, and a decrease in MM in women. Overall DSS was 64% during the mean follow up (43 months). Age, T-NHL, lambda light chain restriction in MM, and male sex in CLL/SLL were associated with poor prognosis. In B-NHL, DSS decreased in the following order: hairy cell leukaemia, marginal zone lymphoma, follicular lymphoma, Burkitt lymphoma, ALL, DLBCL, CLL, MM, and mantle cell lymphoma.

CONCLUSIONS

The incidence of NHL in Tyrol has changed in the past decade, with a significant increase in DLBCL, decrease in CLL/SLL in men, and decrease in MM in women.

Paraffin section interphase fluorescence in situ hybridization in the diagnosis and classification of non-hodgkin lymphomas

Cytogenetic data can contribute valuable information that may assist in the diagnosis and classification of non-Hodgkin lymphomas and may in some cases also provide prognostic information. Interphase fluorescence in situ hybridization (FISH) studies offer the ability to assess for characteristic cytogenetic abnormalities even when material for standard metaphase cytogenetic analysis is not available. This review discusses the use of FISH in paraffin-embedded material with particular attention paid to the use of intact thin paraffin sections. The basic principles of FISH analysis are summarized, the advantages and disadvantages of analysis of thin paraffin sections rather than intact nuclei are discussed, and the more commonly encountered artifacts are considered. Each of the well-characterized cytogenetic abnormalities that are associated with particular types of non-Hodgkin lymphoma and can be detected with commercially available FISH probes is discussed individually. In particular, their incidence in various types of lymphoma is reviewed, the types of commercially available FISH probes to detect such abnormalities are discussed, and clinical situations where such analysis can be of diagnostic utility are described.

Helicobacter pylori (H. pylori) molecular signature in conjunctival mucosa-associated lymphoid tissue (MALT) lymphoma

Conjunctival mucosa-associated lymphoid tissue (MALT) lymphoma is an extranodal marginal zone B-cell lymphoma that is characterized by an exaggerated clonal expansion of B cells, which implicate a pathological proliferative response to antigen(s) including bacteria. Helicobacter pylori (H. pylori) infection is recognized as one of the causative agents of gastric MALT lymphoma; however, it has not been reported in extra gastric MALT lymphoma. We studied 5 patients (4 adults and 1 child) with salmon-colored conjunctival lesions. One patient also had a history of abnormal bone marrow biopsy a year earlier with lymphoid aggregates involving 5% of the overall bone marrow. The conjunctival lesions of the 5 patients were biopsied. Histopathological diagnoses were consistent with conjunctival MALT lymphoma. Lymphoma and normal conjunctival cells were microdissected using laser capture microscopy or manual techniques. DNA was extracted and subjected to PCR amplification using H. pylori gene-specific primers from the urease B and vac/m2 gene. Cells from chronic conjunctivitis (normal lymphocytes), conjunctival human T-cell lymphotropic virus type-1/adult T-cell leukemia/lymphoma (HTLV-1/ATL), and orbital B-cell lymphoma were also microdissected, processed and analyzed. PCR amplification and Southern blot hybridization demonstrated H. pylori DNA in the conjunctival MALT lymphoma cells of 4/5 cases. The negative case was the one with a history of abnormal bone marrow. In contrast, H. pylori gene was not detected in normal conjunctival cells from the cases of MALT lymphoma or the lymphocytes, ATL and orbital B-lymphoma cells from the controls. These data suggest that H. pylori may play a role in conjunctival MALT lymphoma.

BCL10 Mediates Lipopolysaccharide/Toll-like Receptor-4 Signaling through Interaction with Pellino2

Toll-like receptor (TLR) pathways signal through microbial components stimulation to induce innate immune responses. Herein, we demonstrate that BCL10, a critical molecule that signals between the T cell receptor and IkappaB kinase complexes, is involved in the innate immune system and is required for appropriate TLR4 pathway and nuclear factor-kappaB (NF-kappaB) activation. In response to lipopolysaccharide (LPS) stimulation, BCL10 was recruited to TLR4 signaling complexes and associated with Pellino2, an essential component down-stream of BCL10 in the TLR4 pathway. In a BCL10-deficient macrophage cell line, LPS-induced NF-kappaB activation was consistently defective, whereas activator protein-1 and Elk-1 signaling was intact. In addition, we found that BCL10 was targeted by SOCS3 for negative regulation in LPS signaling. The recruitment of BCL10 to TLR4 signaling complexes was attenuated by induced expression of SOCS3 in a feedback loop. Furthermore, ectopic SOCS3 expression blocked the interaction between BCL10 and Pellino2 together with BCL10-generated NF-kappaB activation and inducible nitric-oxide synthase expression. Together, these data define an important role of BCL10 in the innate immune system.

Systemic Tropheryma whippleii Infection Associated With Monoclonal B-Cell Proliferation: A Helicobacter pylori–Type Pathogenesis?

We report a case of Whipple disease in a 55-year-old woman who presented with arthralgia, weight loss, and lymphadenopathy. Tropheryma whippleii bacilli were identified in the mesenteric lymph nodes by diastase-resistant periodic acid–Schiff stain and confirmed by electron microscopy. Retrospectively, previous biopsy specimens from the duodenum and right axillary lymph node of this patient, which were initially considered to demonstrate reactive changes, also showed features consistent with involvement by Whipple disease. At the time of presentation, a large κ-restricted monoclonal B-cell population with the phenotype CD20+CD19+CD5−CD10− was identified in the patient's peripheral blood, lymph nodes, and bone marrow by flow cytometry study. The monoclonality of the mesenteric lymph node B cells was confirmed by immunohistochemical stain for κ chain after antigen retrieval and also by polymerase chain reaction with the primer set targeting FR2-VH. Routine cytogenetic study failed to reveal any chromosomal abnormalities, and polymerase chain reaction for Bcl-2 major and minor breakpoint cluster of t(14:18) was not detected. The monoclonal B cells have persisted in blood for the entire follow-up period (10 months). The possibility of reactive monoclonal B-cell proliferation versus Whipple disease–related B-cell lymphoma is discussed.

Differential Requirement for Malt1 in T and B Cell Antigen Receptor Signaling

The translocation t(11;18)(q21;q21) involving MALT1 is the most common chromosomal abnormality in lymphomas of mucosa-associated lymphoid tissue. Although the paracaspase MALT1 can bind to BCL10, the physiological function of MALT1 is unknown. Using mouse models, we show that Malt1 is essential for T cell activation, proliferation, and IL-2 production in response to TCR ligation and strictly required for signal-specific NF-kappaB activation induced by the TCR but not TNF-alpha or IL-1 signaling. Malt1 operates downstream of Bcl10, controls the catalytic activity of the canonical IKK complex, and regulates the signaling of Jnk and p38 MAP kinases. In contrast to Bcl10 disruption, however, inactivation of Malt1 has only mild effects on B cell activation and does not cause defects during neurodevelopment. Thus, Malt1 is an essential regulator of Bcl10 signaling that is differentially required depending on cellular context.

Defective development and function of Bcl10-deficient follicular, marginal zone and B1 B cells

Bcl10 is an intracellular protein essential for nuclear factor (NF)-kappaB activation after lymphocyte antigen receptor stimulation. Using knockout mice, we show that absence of Bcl10 impeded conversion from transitional type 2 to mature follicular B cells and caused substantial decreases in marginal zone and B1 B cells. Bcl10-deficient B cells showed no excessive apoptosis. However, both Bcl10-deficient follicular and marginal zone B cells failed to proliferate normally, although Bcl10-deficient marginal zone B cells uniquely failed to activate NF-kappaB efficiently after stimulation with lipopolysaccharide. Bcl10-deficient marginal zone B cells did not capture antigens, and Bcl10-deficient (Bcl10-/-) mice failed to initiate humoral responses, leading to an inability to clear blood-borne bacteria. Thus, Bcl10 is essential for the development of all mature B cell subsets.

MALT Lymphomas

Mucosa-associated lymphoid tissue (MALT) lymphomas occur in a variety of organs, including the orbit, conjunctiva, salivary glands, skin, thyroid gland, lungs, stomach, and intestine. These tumors are often localized and of indolent clinical behavior. Diagnosis is made by pathologic evaluation of a tissue biopsy. Careful staging is mandatory and tailored to the initial presentation. Staging includes a history and physical, chemistries, computed tomography scan, and bone marrow biopsy. This information is supplemented with an ear, nose, and throat consultation, esophagogastro-duodenoscopy, colonoscopy, endoscopic ultrasound of the stomach, and cytogenetic/immunohistochemical analysis of the tumors. Treatment is tailored to organ involvement and stage at presentation. Eradication of Helicobacter pylori using a triple anti-H. pylori regimen approved by the US Food and Drug Administration is standard therapy for all H. pylori-positive gastric MALT lymphomas. Endoscopic ultrasound- and computed tomography-staged gastric MALT stage IE tumors will achieve a complete response with this approach in approximately 60% to 90% of patients (the more superficial the tumor, the better the response). Patients with tumors that are T4 node-positive Musshoff stage IIE1 and IIE2 or tumors with adverse cytogenetics should receive radiotherapy or surgery with or without radiotherapy. Tumors with a significant high-grade component or large cell tumors with a minor low-grade MALT component should receive CHOP (cyclophosphamide, doxorubicin, vincristine, and prednisone)-based chemotherapy. Localized MALT lymphomas of the orbit, conjunctiva, salivary glands, and thyroid gland are treated successfully with radiotherapy. Surgery as first-line therapy for gastric MALT lymphomas was replaced by attempts at organ preservation. In the past, margin-free surgical excision or tumor debulking followed by radiation therapy and chemotherapy has been highly effective for gastric MALT lymphomas. Therefore, surgical excision of large cell or bulky tumors of the stomach, thyroid, lung, and salivary gland, followed by adjuvant radiotherapy or chemotherapy, may still be an important consideration in selected patients. Surgery still has a role for patients with relapsed or refractory low-grade disease and life-threatening hemorrhage. Disseminated MALT lymphomas are incurable and are treated primarily with chemotherapy according to symptoms.

Nodal marginal zone B-cell lymphoma with a novel t(X;5)(q28;q22): conventional and molecular cytogenetic analysis

Cytogenetic studies provide important information for the diagnosis and classification of malignant lymphomas that in some cases also has prognostic significance. Furthermore, the investigation of isolated novel cytogenetic findings in malignant lymphoma has led to the discovery of many important oncogenes and tumor suppressor genes. For this reason, a case of nodal marginal zone B-cell lymphoma in a 72-year-old woman is described in which analysis by conventional and molecular cytogenetic techniques demonstrated the presence of a t(X:5)(q28;q22) as the sole chromosomal abnormality. This translocation has not been previously reported in the literature.

Gastric neoplasia

This review summarizes the significant recent advances in our understanding of the clinical, epidemiologic, and pathologic aspects of gastric adenocarcinoma, gastrointestinal stromal tumors (GISTs), and mucosa-associated lymphoid tissue (MALT) lymphoma. Most of the advances in distal gastric adenocarcinoma are in its etiology and pathogenesis. The modulation of the inflammatory response to Helicobacter pylori organisms has been determined to be at the center of the precancerous process. These advances in the understanding of the pathogenesis of H. pylori-related carcinogenesis are relevant to the design of prevention strategies in high-risk populations. New markers of GISTs have focused on the cell of origin and have made possible the development and monitoring of new drugs that are effective even in metastatic tumors. MALT lymphomas have been causally associated with H. pylori infection. Molecular markers are useful to distinguish tumors that respond to H. pylori eradication from those requiring classic chemotherapy.