Other cancers in patients with gastric MALT lymphoma

Second Cancers in a Patient with Gastric MALT Lymphoma

Mucosa-associated lymphoid tissue (MALT) lymphoma is an extranodal low-grade B-cell lymphoma, which is thought to arise from a background of chronic immune stimulation, bacterial, viral, or autoimmune stimuli. Treatment advances have increased the number of MALT lymphoma survivors, but there is still debate as to whether these patients are at a higher risk of developing second cancers. This is a case of a long-surviving (>20 years) patient with multiple diagnosed malignancies following MALT lymphoma. We describe how modern oncological treatment plans can provide patients with prolonged survival and increased quality of life despite increasing age and multiple malignancies.

Risk of second malignancies in patients with gastric marginal zone lymphomas of mucosa associate lymphoid tissue (MALT)

BACKGROUND

It is controversial whether patients with gastric marginal zone lymphomas of mucosa associated lymphoid tissue (MALT) have higher risk of second malignancies. The aim of this study was to define the risk of second malignancies in these patients.

METHODS

We analyzed prospective follow-up data of 146 consecutive patients with gastric MALT lymphoma treated at Aichi Cancer Center Hospital and compared the incidence of second malignancies with that in the general population. We calculated the standardized incidence ratio (SIR), using age- and sex-specific incidence rates from the Aichi Cancer Registry.

RESULTS

The median follow-up period was 74 months. A total of 27 tumors occurred in 22 patients (15.1%), including 19 solid tumors. Of these, nine tumors were detected concomitantly with, and 18 tumors following, the diagnosis of gastric MALT lymphoma. Four patients had two second malignancies each. For the entire group, the SIR of an additional malignancy was 3.39 (95% confidence interval [CI] 2.11-4.66). An increased incidence of solid tumors (SIR 2.91 [1.60-4.22]) and hematologic malignancies (SIR 5.54 [1.70-9.38]) were seen. In addition, there was increased risk for development of second malignancies during follow up (SIR 2.26 [1.21-3.30]). Chemotherapy for treatment of MALT was an independent risk factor for second malignancies (age-sex adjusted hazard ratio 3.98 [1.47-10.79].

CONCLUSIONS

Compared with the general population, patients with gastric MALT lymphoma are at increased risk for second malignancies, including gastric cancer.

The role of radiotherapy in the treatment of gastric mucosa-associated lymphoid tissue lymphoma

Purpose

To assess radiotherapy for patients with early stage gastric mucosa-associated lymphoid tissue (MALT) lymphoma with respect to survival, treatment response, and complications.

Materials and Methods

Enrolled into this study were 48 patients diagnosed with gastric MALT lymphoma from January 2000 to September 2012. Forty-one patients had low grade and seven had mixed component with high grade. Helicobacter pylori eradication was performed in 33 patients. Thirty-four patients received radiotherapy alone. Ten patients received chemotherapy before radiotherapy, and three patients underwent surgery followed by chemotherapy and radiotherapy. One patient received surgery followed by radiotherapy. All patients received radiotherapy of median dose of 30.6 Gy.

Results

The duration of follow-up ranged from 6 to 158 months (median, 48 months). Five-year overall survival and cause-specific survival rates were 90.3% and 100%. All patients treated with radiotherapy alone achieved pathologic complete remission (pCR) in 31 of the low-grade and in three of the mixed-grade patients. All patients treated with chemotherapy and/or surgery prior to radiotherapy achieved pCR except one patient who received chemotherapy before radiotherapy. During the follow-up period, three patients developed diffuse large B-cell lymphoma in the stomach, and one developed gastric adenocarcinoma after radiotherapy. No grade 3 or higher acute or late complications developed. One patient, who initially exhibited gastroptosis, developed mild atrophy of left kidney.

Conclusion

These findings indicate that a modest dose of radiotherapy alone can achieve a high cure rate for low-grade and even mixed-grade gastric MALT lymphoma without serious toxicity. Patients should be carefully observed after radiotherapy to screen for secondary malignancies.

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.

Risk for second malignancies in non-Hodgkin's lymphoma survivors: a meta-analysis

BACKGROUND

Late side-effects are becoming an important issue in non-Hodgkin's lymphoma (NHL) survivors. We intended to estimate pooled relative risk (RR) of secondary malignant neoplasms (SMNs), to evaluate site-associated RR and the impact of different treatments.

DESIGN

We carried out an electronic search of Medline and EMBASE seeking articles investigating the risk of SMNs and reporting RR measures. The studies were evaluated for heterogeneity before meta-analysis and for publication bias. Pooled RRs were estimated using fixed- and random-effects models.

RESULTS

A total of 23 studies met the inclusion criteria. Pooled RRs of SMNs overall and for solid tumors were 1.88 and 1.32, respectively. We found an excess of risk for several specific cancer sites. Radiotherapy alone did not increase the risk for SMNs, while chemotherapy and combined treatments augmented the RR. Regression analyses revealed a positive significant association for all SMNs with total body irradiation, and for solid SMNs with younger age. No publication bias was observed.

CONCLUSIONS

Our results indicate that NHL patients experience a higher risk for SMNs than the general population and that various treatments have different impact on RR. More information will be necessary to evaluate possible interactions with genetic susceptibility and environmental exposure.

Carcinoma and multiple lymphomas in one patient: establishing the diagnoses and analyzing risk factors

Multiple malignancies may occur in the same patient, and a few reports describe cases with multiple hematologic and non-hematologic neoplasms. We report the case of a patient who showed the sequential occurrence of four different lymphoid neoplasms together with a squamous cell carcinoma of the lung. A 62-year-old man with adenopathy was admitted to the hospital, and lymph node biopsy was positive for low-grade follicular lymphoma. He achieved a partial remission with chemotherapy. Two years later, a PET-CT scan showed a left hilar mass in the lung; biopsy showed a squamous cell carcinoma. Simultaneously, he was diagnosed with diffuse large B cell lymphoma in a neck lymph node; after chemo- and radiotherapy, he achieved a complete response. A restaging PET-CT scan 2 years later revealed a retroperitoneal nodule, and biopsy again showed a low-grade follicular lymphoma, while a biopsy of a cutaneous scalp lesion showed a CD30-positive peripheral T cell lymphoma. After some months, a liver biopsy and a right cervical lymph node biopsy showed a CD30-positive peripheral T cell lymphoma consistent with anaplastic lymphoma kinase-negative anaplastic large cell lymphoma. Flow cytometry and cytogenetic and molecular genetic analysis performed at diagnosis and during the patient’s follow-up confirmed the presence of two clonally distinct B cell lymphomas, while the two T cell neoplasms were confirmed to be clonally related. We discuss the relationship between multiple neoplasms occurring in the same patient and the various possible risk factors involved in their development.

Radiotherapy for low-grade gastric marginal zone lymphoma: a retrospective study

BACKGROUND

We evaluated the efficacy and toxicity of radiotherapy (RT) in patients with low-grade gastric marginal zone lymphoma.

METHODS

A retrospective review of consecutive cases of gastric marginal zone lymphoma treated by radical RT at the Peter MacCallum Cancer Centre and Radiation Oncology Victoria between January 1980 and September 2003 was carried out.

RESULTS

Eighteen patients (11 men and 7 women) were identified. The median age at commencement of RT was 65 years (range 42-84 years). Prior treatment included Helicobacter pylori eradication in 12 patients, chemotherapy in 7 and surgery in 2, whereas 2 patients had no prior therapy. The median time to progression after commencement of last treatment before RT was 4.8 months (range 0-129.4 months). The radiation fields included the stomach plus perigastric and coeliac nodes in 15 patients (83%), stomach plus spleen in 2 patients (11%) and stomach plus para-aortic nodes in 1 patient (6%). The median RT dose was 30 Gy (range 30-36 Gy) in a median 20 fractions (range 17-24 fractions). One patient required treatment interruption for acute toxicity. A complete response on post-RT biopsies was achieved in 17 of 18 patients (94%). With a median follow up of 4.5 years after RT, 3 of these 17 patients (18%) have had a recurrence. At the last follow up, 11 patients were alive in continuous complete histological remission. No late renal toxicity was identified.

CONCLUSION

Radiotherapy is an effective, well-tolerated treatment for patients with low-grade gastric marginal zone lymphoma, including those who have had prior therapy.

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.

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

PURPOSE

The aim of this study was to define the risk of second cancer in nongastric marginal zone lymphomas of mucosa-associated lymphoid tissue (MALT).

EXPERIMENTAL DESIGN

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.

RESULTS

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.

CONCLUSIONS

Patients with nongastric MALT lymphomas are not at increased risk for other neoplasms compared with the general population of the same geographic area.

Synchronous and metachronous occurrence of gastric adenocarcinoma and gastric lymphoma: A review of the literature

The occurrence of both primary gastric lymphoma and gastric adenocarcinoma in the same patient is a rare entity. The possible causative factors of synchronous or metachronous occurrence of both malignancies and varieties in the treatment modalities are reviewed according to published cases in English language medical literature.

Treatment of gastric mucosa-associated lymphoid tissue lymphoma: Helicobacter pylori eradication and beyond

Gastric mucosa-associated lymphoid tissue (MALT) lymphoma is the paradigm of lymphomas developing in extranodal areas after antigen stimulation. In the stomach, Helicobacter pylori colonization induces the appearance of MALT and, eventually, MALT-derived lymphoma. This type of lymphoma is initially a localized form of disease, but may disseminate and transform into high-grade lymphoma, making full staging (as for nodal lymphomas) and endoscopic ultrasonography to evaluate the penetration of the lymphoma through the gastric wall mandatory. In localized gastric MALT lymphoma, the first step in treatment is eradication of H. pylori, which results in 60-90% regression. This response is maintained for years in most patients, with only 10-15% relapse, frequently precipitated by H. pylori reinfection. A component of high-grade lymphoma, penetration to gastric serosa or beyond and translocation t(11;18) are the main factors that make lymphoma resistant to eradication. Surgery or radiotherapy can cure localized lymphomas in 75-90% of patients. Chemotherapy with alkylating agents, combination chemotherapy and purine analogs, and anti-CD20 antibodies can also induce remission of localized lymphomas refractory to eradication, as well as locally advanced and disseminated lymphomas. The optimum chemotherapy treatment for advanced disease has not yet been established; however, combination therapy, including purine analogs with or without anti-CD20, may be a promising option. Despite histological responses and prolonged remissions, residual molecular disease can be demonstrated in most cases treated with H. pylori eradication, radiotherapy or alkylating agents, and even after more intense chemotherapy, although this does not seem to lead to late relapses. High-grade gastric MALT lymphoma should be treated with chemotherapy, with cyclophosphamide, doxorubicin, oncovin and prednisone being the best first-line option. All gastric MALT lymphomas associated with H. pylori should receive eradication treatment in addition to other required treatment.

Long-term clinical outcome of Helicobacter pylori eradication for gastric mucosa-associated lymphoid tissue lymphoma with a reference to second-line treatment

BACKGROUND

The goals of the current study were to elucidate the long-term outcome of Helicobacter pylori eradication therapy for gastric mucosa-associated lymphoid tissue (MALT) lymphoma and to clarify the therapeutic efficacy of stomach-conserving treatments for patients not responding to eradication therapy.

METHODS

Ninety-six patients with gastric MALT lymphoma, including 17 patients with areas of diffuse large B-cell lymphoma, were treated by H. pylori eradication. Patients not responding to eradication therapy underwent either a gastrectomy, multiagent chemotherapy, oral monochemotherapy (OMC), or radiotherapy (RT). Predictive factors for the response to eradication therapy, overall survival (OS), and event-free survival (EFS) were determined by the Kaplan-Meier analysis with the log-rank test. The efficacy of second-line treatment was compared between OMC and RT.

RESULTS

After eradication therapy, 62 (65%) patients achieved complete disease remission (CR). Transient histologic disease recurrence was confirmed in 4 (6.5%) of 62 patients with CR during the follow-up (median, 37.5 months). The OS and EFS probabilities after 5 years were 0.96 and 0.80, respectively. Second-line treatment was performed in 31 patients; gastrectomy in 4 patients, multiagent chemotherapy in 5 patients, OMC in 12 patients, and RT in 10 patients. There were no differences in the CR rate, OS, EFS, or toxicity between the OMC and RT groups.

CONCLUSIONS

H. pylori eradication therapy was an effective first-line treatment for patients with gastric MALT lymphoma, which led to a favorable long-term outcome. OMC and RT had an equivalent efficacy as a second-line treatment in nonresponding patients to eradication therapy.

Patient with immunoproliferative disease and lung carcinoma: A case report

There are a number of reports on collision occurrence of non-hematologic cancers and Non-Hodgkin's lymphoma (NHL) and multiple myeloma. In this report we present a case of patient with immunoproliferative disease, extramedullary plasmocytoma and NHL-lymphoplasmocytoid lymphoma (LPL) and squamous cell carcinoma of the lung. After diagnosis of extramedullary plasmocytoma cytostatic therapy was commenced and the patient was well. Five years after patient was clinically worse and diagnostic evaluation this time revealed lymphoplasmocytoid cells in bone marrow. Five months later malignant morphologically undifferentiated cells were found in bone marrow which were by immunocytochemistry established as CD38 positive. After the patient's death, disseminated NHL-LPL and squamous cell carcinoma of lung was confirmed. In the report, we compared clinical course and diagnostic findings of our patient with literature data. We have also discussed the possible relationship of multiple B-cell lymphoid tumors and squamous cell carcinoma concluding that multidiscplinary diagnostic tools are essential not only for carcinoma diagnosis and follow-up, but also for further understanding of carcinogenesis.

Early cancer of the stomach arising after successful treatment of gastric MALT lymphoma in patients with autoimmune disease

BACKGROUND

Extranodal marginal zone B-cell lymphoma of the mucosa associated lymphoid tissue (MALT lymphoma) arises in lymphoid tissue acquired through chronic antigenic stimulation as exemplified by Helicobacter pylori. Secondary development of gastric cancer, however, is thought to be a rare event. The detection of a signet ring cell carcinoma during follow-up endoscopy after successful therapy of MALT lymphoma in a patient with Sjögren's syndrome prompted us to analyse the frequency of subsequent gastric cancer in patients with underlying autoimmune disease (AD).

METHODS

Patients with early stage MALT lymphoma and an underlying AD were evaluated for the occurrence of a secondary gastric cancer during the course of follow-up. Data analysed included the type of AD, stage of MALT lymphoma, H. pylori status, treatment for MALT lymphoma and response, follow-up, the presence of a secondary cancer, and time to development of cancer. In all patients, histologic samples were reassessed for the extent of gastritis, presence of intestinal metaplasia or focal atrophy at the time of lymphoma diagnosis.

RESULTS

A total of eight patients with overt AD at the time of diagnosis of MALT lymphoma were identified. All patients were women aged between 56 and 77 years; 5 had Sjögren's syndrome, 2 had autoimmune thyroiditis (1 along with psoriasis) and 1 suffered from polymyalgia rheumatica. All patients had early stage MALT lymphoma restricted to the mucosa and submucosa at the time of diagnosis, and the presence of H. pylori was found in all cases. Two of these patients achieved complete remission (CR) of the lymphoma following H. pylori eradication, while six were judged unresponsive and underwent chemotherapy, resulting in CR in all cases. One patient died from stroke while being in CR for 2 months following chemotherapy. Two patients (25%) developed early cancer limited to the gastric mucosa while being in CR from lymphoma for 9 and 27 months, respectively, and underwent partial gastrectomy. Final staging of gastric cancer revealed pT1pN0M0 in both cases. Of the remaining 5 cases, 1 patient had a local lymphoma relapse 18 months after CR and was salvaged with radiotherapy. In the remaining 4 patients, no evidence of lymphoma recurrence or a second malignancy has been found so far by regular follow-up every 3 months for a time-span between 52 and 63 months after initial diagnosis.

CONCLUSION

Patients with concurrent MALT lymphoma and an underlying autoimmune condition show not only an impaired response to H. pylori eradication but might also be at increased risk for the development of gastric cancer. In view of this, such patients should be followed closely by regular endoscopies after remission of MALT lymphoma.

Development of early gastric cancer 4 and 5 years after complete remission of Helicobacter pylori associated gastric low grade marginal zone B cell lymphoma of MALT type

AIM: To report 3 of 120 patients on the German MALT lymphoma trial with H. pylori associated gastric MALT lymphoma who developed early gastric cancer 4 and 5 years, after complete lymphoma remission following cure of H. pylori infection.

PATIENTS AND RESULTS: Three patients (two men, 74 and 70 years; one women, 77 years) with H. pylori-associated low-grade MALT lymphoma achieved complete lymphoma remission after being cured. Surveillance endoscopies were performed twice a year in accordance to the protocol. Four years after complete lymphoma remission in two patients, and after 5 years in the other, early gastric adenocarcinoma of the mucosa-type, type II a and type II c, respectively, was detetcted, which were completely removed by endoscopic mucosa resection. In one patient, the gastric cancer was diagnosed at the same location as the previous MALT lymphoma, in the other patients it was detected at different sites of the stomach distant from location of the previous MALT lymphoma. The patients were H. pylori negative during the whole follow-up time.

CONCLUSION: These findings strengthen the importance of regular Long term follow-up endoscopies in patients with complete remission of gastric MALT lymphoma after cure of H. pylori infection. Furthermore, gastric adenocarcinoma may develop despite eradication of H. pylori.

Diffuse large B-cell non-Hodgkin's lymphoma presenting as a vaginal mass in a patient with a history of intestinal mucosa-associated lymphoid tissue (MALT) lymphoma

Vaginal involvement in non-Hodgkin's lymphoma is uncommon and is often secondary to disseminated disease. Primary disease at this site is quite rare. We present here an unusual case of a patient who developed a diffuse large B-cell lymphoma presenting as a vaginal mass after having been treated for primary intestinal mucosa-associated lymphoid tissue (MALT) lymphoma 4 years earlier. Combined chemotherapy and radiation therapy for the intestinal MALT lymphoma produced complete remission that lasted for 2 years. Chemotherapy given for the diffuse large B-cell lymphoma with secondary vaginal involvement produced a second complete remission. The second remission was consolidated with high-dose chemotherapy and autologous bone marrow transplantation. Although the patient died from complications related to the transplant procedure, the disease was in complete remission at the time of her death. Given the rarity of primary intestinal MALT lymphoma and primary vaginal lymphoma, no standard treatment has been established. Treatment options have included chemotherapy, radiation therapy, or surgery, given alone or in combination.

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.

Association of gastric and Waldeyer's ring lymphoma: a molecular study

The coexistence of Waldeyer's ring and gastrointestinal non-Hodgkin's lymphomas at presentation is well known. Moreover, localized gastrointestinal relapses following successful treatment of lymphomas of Waldeyer's ring and thyroid lymphomas occurring after a prolonged disease-free interval have also been described. We report two cases of concomitant lymphoma in Waldeyer's ring and stomach. On the basis of the molecular analysis of the immunoglobulin heavy chain gene rearrangements, two different patterns of concomitant involvement by a lymphoma in Waldeyer's ring and in the gastrointestinal region seem to exist. One is represented by the preferential dissemination of the lymphoma from one site to the other, the second by the apparently independent growth of clonally unrelated lymphomas at each site.

Mucosa-associated lymphoid tissue lymphomas

Mucosa-associated lymphoid tissue (MALT) lymphoma has attracted attention because its concept has amalgamated the study of etiology and pathogenesis in an intriguing group of lymphomas. MALT lymphomas are a B-cell malignancy with characteristic lymphoepithelial lesions; cells are CD20-positive and CD5- and CD10-negative. The molecular changes observed include trisomy 3, t(11;18), and t(1;14) translocations. They commonly occur in the stomach, orbit, salivary glands, and thyroid. Localized disease is present in 60% to 70% of patients. Involvement of multiple extranodal sites has been observed at presentation or during the course of disease. Lymphocyte homing has been implicated in gastrointestinal MALT and may be involved in other MALT lymphomas. Local therapy, either through surgery or radiotherapy, is curative in a high proportion of patients. MALT lymphomas respond to chemotherapy, but there is no evidence that cure can be achieved, although prolonged survival is common. Long-term follow-up is essential for study of the outcomes in this disease.

Mucosa-associated lymphoid tissue-type lymphomas occurring in post-transplantation patients

Post-transplantation lymphoproliferative disorders (PTLDs) are usually Epstein-Barr virus (EBV)-associated B-cell lymphoproliferative disorders that vary in their morphologic spectrum. Extranodal marginal zone lymphomas of the mucosa-associated lymphoid tissue-type (MALT-type) have not been considered to be part of this spectrum. The authors encountered five such cases recently. The clinical, histopathologic, and immunophenotypic features are reported. There were three men and two women with a mean age of 51.2 years (range, 48-63 years). Two patients were cardiac transplant recipients, two patients were liver transplant recipients, and the remaining patient was a renal transplant patient. Sites of lymphoma were the stomach in three patients and the parotid gland in two patients. Mean time to the lymphoma was 84 months after transplantation. All patients had morphologic features of low-grade extranodal marginal zone lymphomas of the MALT-type, and Helicobacter pylori was present in all three gastric cases. All patients exhibited the B-cell immunophenotype and were negative for EBV by in situ hybridization. These lymphomas were treated with a variety of modalities, including reduction of immunosuppression, antibiotics, surgical resection, radiation therapy, and chemotherapy. At last follow-up, one patient had developed signet ring adenocarcinoma at 27 months but had no evidence of PTLD, one patient relapsed at 17 months but is alive with stable disease at 24 months, and the remaining patients were alive without disease at 11, 12, and 14 months. Extranodal low-grade MALT-type lymphomas can occur in the post-transplantation setting and generally develop years after transplant. As seen in immunocompetent patients, EBV appears to play no role in the pathogenesis of these lymphomas. These lymphomas appear to have more in common with MALT-type lymphomas in nonimmunocompromised patients than conventional PTLDs, although they occur in "at-risk" patients due to their immunosuppressive therapy. These lymphomas do not appear to be clinically aggressive. Recognition of MALT-type lymphomas in the post-transplantation setting as an indolent disease avoids unnecessary treatment.