Primary lymphomas in the gastrointestinal tract

Primary gastrointestinal (GI) lymphomas are uncommon diseases that can involve the whole GI tract. The etiologies of the disease remain unclear, and potential risk factors include celiac disease, Helicobacter pylori infection, use of immunosuppressive agents, human immunodeficiency virus (HIV) or Epstein–Barr virus (EBV) infection and inflammatory bowel disease, etc. Diffuse large B‐cell lymphoma (DLBCL) and mucosa‐associated lymphoid tissue (MALT) lymphoma are the most common subtypes of GI lymphomas. B‐cell lymphomas of the GI tract are more common in Western countries, while in Asia–Pacific region T‐cell lymphomas are more frequently reported. In this review, lymphomas in the esophagus, stomach and intestine are described, including their epidemiology, histology, clinical manifestations, endoscopic findings, radiological features and treatment.     

Peripheral T cell lymphoma in Asia

Peripheral T-cell lymphomas (PTCLs) comprise a heterogeneous group of mature T- and NK-cell neoplasms, the incidence of which is higher in Asian countries than in Western countries. Although its etiology is mainly unknown, several risk factors (such as genetic factors, abnormal immunity, environmental factors, and infectious causes) have been proposed. PTCL are classified based on a combination of several parameters, including morphology, site of presentation, viral status, immunophenotype, and specific genetic alterations. Their classification is ongoing, with the emergence of new entities and refinement of existing entities because of the development of diagnostic markers and new genetic alterations. This review presents epidemiologic data for PTCL in Asia, together with recent progress in the pathology of PTCL compared with the WHO 2008 classification.     

Frequent occurrence of B-cell lymphomas in angioimmunoblastic T-cell lymphoma and proliferation of Epstein-Barr virus-infected cells in early cases

Secondary lymphomas occurring in the setting of angioimmunoblastic T-cell lymphoma (AILT) are considered to be rare. Their occurrence has been attributed to Epstein-Barr virus (EBV)-associated lymphoproliferations. A previous study detected a dysregulated hypermutation process in B-cells of AILT. The present study aimed at estimating the frequency of B-cell lymphomas in AILT. By studying the expression of EBV and activation-induced cytidine deaminase (AID) as an indicator of hypermutating cells, we assessed whether B-cell lymphoproliferations in AILT were strictly associated with EBV and whether hypermutation might contribute to lymphomagenesis. Among 161 cases of AILT, diagnosed between 1996 and 2005 at the lymph node registry, Frankfurt, Germany, 19 cases were detected that also had B-cell non-Hodgkin lymphoma (NHL) and two cases had classical Hodgkin lymphoma (HL). EBV was detected in tumour cells of 7/18 NHL and both HL, suggesting that factors other than EBV contribute to lymphomagenesis. AID was expressed in AILT in large cells disseminated in the tissue, implying that the process of somatic hypermutation is ongoing in AILT, although the GC architecture is disrupted. This might be relevant in the development of secondary lymphomas.     

Characterization of posttransplant lymphomas that express T-cell- associated markers: immunophenotypes, molecular genetics, cytogenetics, and heterotransplantation in severe combined immunodeficient mice

Immunosuppressed individuals are at high risk for the development of hematologic malignancies. The typical lymphomas arising in organ transplant recipients are B-cell non-Hodgkin's lymphomas that contain Epstein-Barr virus (EBV) DNA sequences. We investigated the characteristics of posttransplant lymphomas that lacked expression of the usual markers associated with EBV transformation. We describe four large-cell lymphomas seen recently at our institution. Two of these four cases were CD4+, one was CD8+, and in one staining for CD4 and CD8 expression was not performed. One CD4+ lymphoma was a CD30+, EBV- large- cell lymphoma from a 65-year-old kidney transplant recipient, the second was an EBV+ large-cell lymphoma from a 25-year-old heart transplant patient. Two T-cell lymphomas were EBV+ and had clonal T- cell receptor beta gene rearrangements. The other two lymphomas expressed T-cell markers CD4 and CD43, and lacked expression of B-cell markers CD19, CD20, CD21, CD22, CD23, and surface Ig. Both CD4+ lymphomas were tumorigenic after their heterotransplantation into severe combined immunodeficient (SCID) mice. Cytogenetics, immunophenotyping, and genotyping of the secondary tumors from SCID mice showed their clonality and identity with the patients' primary tumors. Novel CD4+ lymphoma cell lines, LH521/4 and LK418/4, were established from tumors that had been passaged in SCID mice. An immunodeficient environment may facilitate the growth of these T-cell or biphenotypic lymphomas; the etiology of their genesis can include transformation with EBV and other, as yet unidentified mechanisms.     

Posttransplant Lymphoproliferative Disease in Liver Transplant Patients

Posttransplant lymphoproliferative disorders (PTLD) are a life-threatening complication following solid organ transplantation. Many posttransplant lymphomas develop from the uncontrolled proliferation of Epstein–Barr virus (EBV)-infected B-cells, whereas EBV-negative PTLDs were increasingly recognized within the past decade. Major risk factors for the development of PTLDs after liver transplantation are immunosuppressive therapy and the type of underlying disease: viral hepatitis, autoimmune liver disease, or alcoholic liver cirrhosis contribute to an increased risk for PTLD. Therapeutic regimens include reduction of immunosuppression, the anti-CD20 antibody rituximab, and chemotherapy, as well as new approaches using interferon-α and anti-interleukin-6 antibodies. Despite the different therapeutic regimens, mortality from PTLD remains high. Therefore, it is of major importance to identify patients at risk at an early stage of the disease. In this review, risk factors for PTLD development after liver transplantation, clinical presentation, diagnosis, and therapy are discussed.     

EBV-induced human B cell lymphomas in hu-PBL-SCID mice.

Epstein-Barr virus (EBV) infection is associated with Burkitt's lymphoma (BL) in normal individuals and immunoblastic B cell lymphomas in immunosuppressed or HIV-infected individuals. SCID mice reconstituted with human peripheral blood leukocytes (hu-PBL-SCID) from EBV-seropositive donors also may develop spontaneous B cell lymphomas which histologically and phenotypically resemble post-transplant tumors, and are distinct from BL. These tumors always contain EBV DNA. We have noted three different reproducible outcomes depending upon the EBV-seropositive donor used for generation of hu-PBL-SCID mice: (i) no tumors appear; (ii) tumors appear in a fraction of hu-PBL-SCID mice with a 10-20 wk. latent period; or (iii) tumors appear in all hu-PBL-SCID mice within 6-10 wk. Southern blot analysis of late versus early tumors using a probe specific for the EBV terminal repeat sequences (BamNJ), which allows distinction between circular latent and linear replicating genomes, shows that late tumors do not involve active EBV replication but that early tumors do show replicating genomes. In addition, EBV genomes were monoclonal in late tumors but polyclonal in early tumors. These data suggest two mechanisms for EBV lymphomagenesis, slow outgrowth of rare latently-infected B cells, and more rapid transformation of uninfected bystander B cells by replicating virus. The latter process may be highly amenable to therapy in patients at risk for EBV-related lymphomas. In addition, prospective screening of EBV-seropositive transplant recipients in the hu-PBL-SCID model may predict the risk of post-transplant lymphoma development.     

Primary tonsillar lymphomas according to the new World Health Organization classification: to report 87 cases and literature review and analysis

The present study aimed to define the natural history, World Health Organization (WHO) classification, prognostic factors, and treatment outcome of 87 patients with primary lymphoma of the palatine tonsil and literature review and analysis. Between 1990 and March 2008, 87 consecutive patients diagnosed with primary lymphoid malignancy of the palatine tonsil. All pathologic specimens were reviewed and reclassified according to the recent WHO classification. To investigate the association of tonsillar lymphomas with Epstein-Barr virus (EBV), in situ hybridization was performed for 24 tonsillar lymphomas (23 diffuse large B-cell lymphoma (DLBC) and one classic Hodgkin’s disease) and ten normal tonsils as control group. In literature review, we found 26 major related series including 1,602 patients with primary tonsillar lymphoma. The median age of our patients was 52 years (range 11–86 years). There were 39 women and 48 men with a median follow-up of 67 months for living patients. The vast majority (95%) of patients had B-cell phenotype. DLBC was the most frequent histology. In situ hybridization revealed none of 23 DLBC to be positive for EBV. The 5-year disease-free and overall survival rates were 78.9% and 86%, respectively. In the literature review and by analyzing the data collection from 26 major reported series, the median age was 55 years and male/female ratio was 1.3:1. Intermediate grade tumors consisted of 72% of all tonsillar lymphomas and B-cell lymphomas constituted 82% of all cell immunophenotypes. The 5-year disease-free and overall survival rates were 61% and 67%, respectively. The vast majority of tonsillar lymphomas are of B-cell origin and with intermediate to high-grade histology. These neoplasms tend to present in early stage disease and to have favorable outcome. WHO classification predicts more accurately treatment outcome of patients with tonsillar lymphoma. The association of DLBC in the palatine tonsil with EBV infection is infrequent.     

ALK-negative anaplastic large cell lymphoma and Hodgkin's disease of nodular sclerosing type in 2 siblings

Familial clustering of Hodgkin's disease (HD) and increased risk of developing the disease among the siblings of affected patients suggest that both environmental and genetic factors may play an important role in its pathogenesis. An association between Epstein-Barr virus (EBV) and HD has been widely demonstrated. Recently, latent membrane protein of EBV has also been detected in CD30-positive anaplastic large cell lymphoma. Familial aggregation of HD and a three- to seven-fold-increased risk among the siblings of affected patients suggest increased genetically determined susceptibility. No data about genetic factors are available for anaplastic large-cell lymphoma. In this study, the authors report the case of a woman with anaplastic-lymphoma-kinase (ALK)-negative CD30-positive anaplastic large cell lymphoma, whose brother had developed HD 11 years previously. The clinical, histologic, and immunohistochemical features of the 2 lymphomas were studied. Both siblings showed bulky mediastinal involvement, effacement of normal lymph node architecture by large, atypical cells, resembling Reed-Sternberg cells, expression of EBV latent membrane protein-1 in the lymph node specimens, concordance of both HLA classes I and II. The clinical presentations and immunological studies disclose numerous similarities between the 2 cases and can suggest that their association is not fortuitous. At present, in problematic cases, a combination of morphologic, immunophenotypic and genetic studies may contribute to better define the tumour type.     

Lymphoma subtypes in patients with rheumatoid arthritis: increased proportion of diffuse large B cell lymphoma

OBJECTIVE: Patients with rheumatoid arthritis (RA) have an increased risk of developing malignant lymphoma. It is not clear whether the increase is confined to certain subtypes of lymphomas. Immunosuppressive therapy and Epstein-Barr virus (EBV) have been linked to the development of these lymphomas. To gain information about the baseline pattern of lymphoma subtypes in RA before the current widespread use of immunosuppressive drugs, we examined the distribution of lymphoma subtypes and the presence of EBV in a cohort of RA patients with a low frequency and duration of treatment with immunosuppressive drugs. METHODS: By linking data from the Swedish Hospital Discharge Register and the Swedish Cancer Register, 42 cases of lymphoma were identified among 11683 patients with RA in the Uppsala Health Care Region between 1964 and 1984. The medical records and paraffin-embedded lymphoma tissues were collected, and the lymphomas were reclassified using the World Health Organization classification. In situ hybridization was used to detect EBV. RESULTS: Tissues from 35 patients were reviewed. Non-Hodgkin's lymphoma (NHL) was found in 33 patients and Hodgkin's lymphoma in 2 patients. There was an increased frequency of diffuse large B cell lymphoma (DLBCL) (22 of 33 NHL patients, 67%) compared with that in the general population (30-40%). EBV was detected in 5 of 30 examined lymphomas from patients (17%). Twenty of the 22 DLBCL patients had RA with medium or high inflammatory activity, and 6 had been treated with a disease-modifying antirheumatic drug for >or=1 year. CONCLUSION: The findings of this study suggest an increased incidence of one specific lymphoma subtype, DLBCL, in RA patients, as well as a possible association with RA disease activity.     

Malignant lymphoma associated with human AIDS and with SIV-induced immunodeficiency in macaques.

Malignant lymphomas associated with human (HIV) and simian (SIV) immunodeficiency virus infections are reviewed and compared. Recent observation of a high frequency of lymphomas in a series of cynomolgus macaques, highly immunodeficient after infection with SIVsm(smm3) are described. In addition to the increased frequency in human and monkey AIDS, SIV and HIV lymphomas share several important features. Clinically and by histology they present as aggressive high-grade malignant tumors with a predilection for extranodal growth in viscera, skin, central nervous system, testis, and retroorbitally. Most malignant lymphomas are of B-cell origin. AIDS lymphomas in humans are heterogeneous with regard to Epstein-Barr virus (EBV) association. Similarly, most lymphomas in monkeys experimentally infected with SIV tested to date were shown to be associated with an EBV-like simian herpes virus. These observations point to the possibility of using SIV-immunodeficient macaques for study of EBV and other oncogenic and immunosuppressive factors in AIDS-associated lymphomagenesis.     

Association of chronic inflammation, not its treatment, with increased lymphoma risk in rheumatoid arthritis

OBJECTIVE: Chronic inflammatory conditions such as rheumatoid arthritis (RA) have been associated with malignant lymphomas. This study was undertaken to investigate which patients are at highest risk, and whether antirheumatic treatment is hazardous or protective. METHODS: We performed a matched case-control study of 378 consecutive Swedish RA patients in whom malignant lymphoma occurred between 1964 and 1995 (from a population-based RA cohort of 74,651 RA patients), and 378 controls. Information on disease characteristics and treatment from onset of RA until lymphoma diagnosis was abstracted from medical records. Lymphoma specimens were reclassified and tested for Epstein-Barr virus (EBV). Relative risks (odds ratios [ORs]) for lymphomas (by subtype) associated with deciles of cumulative disease activity were assessed, as were ORs associated with drug treatments. RESULTS: The relative risks of lymphoma were only modestly elevated up to the seventh decile of cumulative disease activity. Thereafter, the relative risk increased dramatically (OR ninth decile 9.4 [95% confidence interval 3.1-28.0], OR tenth decile 61.6 [95% confidence interval 21.0-181.0]). Most lymphomas (48%) were of the diffuse large B cell type, but other lymphoma subtypes also displayed an association with cumulative disease activity. Standard nonbiologic treatments did not increase lymphoma risk. EBV was present in 12% of lymphomas. CONCLUSION: Risk of lymphoma is substantially increased in a subset of patients with RA, those with very severe disease. High inflammatory activity, rather than its treatment, is a major risk determinant.     

Epstein-Barr virus in benign lymph node biopsies from individuals infected with the human immunodeficiency virus is associated with concurrent or subsequent development of non-Hodgkin's lymphoma.

Individuals infected with the human immunodeficiency virus (HIV) have an increased incidence of high-grade B-cell lymphoma. In many instances, these lymphomas contain Epstein-Barr viral (EBV) genomes. To investigate the role of EBV in development of HIV-related lymphoma, benign fixed lymph node biopsies from normal individuals and HIV-infected individuals with persistent generalized lymphadenopathy (PGL) were analyzed for EBV sequences by polymerase chain reaction and in situ DNA hybridization techniques. EBV DNA was not detected in any of 16 benign lymph node biopsies from normal individuals, but could be detected from 13 of 35 PGL biopsies. The EBV-infected cells were present in both follicular and interfollicular areas and in both small and large lymphoid cells. The presence of detectable amounts of EBV DNA in the 13 PGL biopsies was associated with an increased incidence of concurrent lymphoma at another site (n = 3) or development of lymphoma in time (n = 2). In contrast, only 1 of 22 individuals with EBV-negative PGL biopsies developed lymphoma in time (P less than .05). EBV was detected in all five lymphomas in which tissue was available for subsequent analysis, including the lymphoma that developed in the individual without EBV in his previous PGL biopsy. These findings support the hypothesis that EBV plays a role in development of some HIV-related lymphomas. Detectable EBV lymphoproliferations occur in a few PGL biopsies and are associated with a significant risk of EBV DNA-positive non-Hodgkin's lymphoma.     

Epstein-Barr virus-associated T-cell acute lymphoblastic leukaemia

Epstein-Barr virus (EBV) is frequently detected in haematological malignancies, including Burkitt's lymphomas/leukaemias, Hodgkin's diseases and non-Hodgkin's lymphomas. However, immature T-cell malignancies associated with EBV have not been reported previously. We report a patient with T-cell acute lymphoblastic leukaemia (T-ALL), whose leukaemic cells had EBV, confirmed by Southern blotting and in situ hybridization. The EBV existed in episomal form and was detected in most leukaemic cells, but not in bystander normal B-cells. The leukaemic cells, massively infiltrated into the liver and spleen, were resistant to chemotherapy. EBV might be associated with tumorigenesis of T-ALL, and characteristic clinical features of the patient.     

Quantification of circulating Epstein-Barr virus (EBV) DNA in the diagnosis and monitoring of natural killer cell and EBV-positive lymphomas in immunocompetent patients

In Epstein-Barr-virus (EBV)-positive lymphomas in immunocompetent patients, release of EBV DNA from tumor cells into the plasma might be useful for disease monitoring and prognostication. To test this hypothesis, we quantified serially plasma EBV DNA by quantitative polymerase chain reaction in 39 cases of EBV-positive (natural killer [NK] cell, n = 23; T cell, n = 8; B cell, n = 4; Hodgkin, n = 4) lymphomas. As control, EBV DNA was undetectable in 34 cases of EBV-negative lymphomas at diagnosis and during chemotherapy. In all cases of EBV-positive lymphomas, EBV DNA was detectable (10(5)-10(10) copies/mL) at diagnosis. It paralleled the clinical course, with EBV DNA becoming undetectable at remission and remaining elevated in refractory disease. On multivariate analysis, high-presentation EBV DNA (> 7.3 x 10(7) copies/mL) was significantly associated with an inferior overall survival (OS). Subgroup analysis of NK cell lymphomas, the largest cohort in this study, showed that presentation EBV DNA was correlated with disease stage and lactate dehydrogenase. On multivariate analysis, high-presentation EBV DNA (> 6.1 x 10(7) copies/mL) was significantly associated with an inferior disease-free survival. During treatment, patients with EBV DNA that showed further increases or failed to become undetectable had significantly inferior OS. In EBV-positive lymphomas, plasma EBV DNA is valuable as a tumor biomarker and for prognostication.     

Diagnosis of Epstein-Barr virus-associated diseases

Epstein-Barr virus (EBV) is a common DNA virus distributed worldwide. Usually the initial infection involves the upper respiratory tract without any problems and almost the entire population more than 25 years old test positive for anti-EBV antibodies. However, EBV often causes not only acute lytic infection but also chronic active infection with B cells and even T cells. In addition the EBV genome has been detected in tumors of hematopoietic or epithelial cell origin such as Burkitt's lymphomas, Hodgkin's disease, NK/T cell lymphomas, nasopharyngeal carcinomas (NPCs) and gastric adenocarcinomas. It is clearly important to make a correct diagnosis for EBV associated diseases and monitor the EBV load in individual patients for an appropriate therapy. In this paper recent advances in serological, immunological and molecular approaches for detection of EBV associated disease are described.     

Tumoren nach Nierentransplantation

Renal transplant recipients are 2?C4 times more likely to develop tumors than the general population, the risks being particularly increased for skin cancer, lymphoma and renal cell carcinoma. The increased incidence of malignancies has been attributed to the immunosuppressive therapy which results in impaired immune surveillance for malignant transformations as well as increased susceptibility for oncogenic viruses. This is particularly highlighted by the role of primary infection with Epstein-Barr virus (EBV) in post-transplantation lymphomas. However, renal chronic kidney disease itself is associated with an increased risk especially for renal and bladder tumors. There are also differences between immunosuppressive agents concerning tumor risk. The increased incidences of certain tumors as well as the associated risk factors have implications regarding tumor prevention, screening and treatment.     

Epstein-Barr virus clonality in lymphomas occurring in patients with rheumatoid arthritis

Objective. A causative role for Epstein-Barr virus (EBV) in the development of lymphoma in patients with rheumatoid arthritis (RA) has been proposed. We investigated the molecular features of EBV-positive diffuse large cell lymphomas in 2 patients with RA. Methods. Southern blot analysis for immunoglobulin gene rearrangements, terminal repeat analysis for clonality of the EBV genome, and double-labeling of the lymphoma cells by in situ hybridization and immuno-peroxidase staining were performed. Results. In both cases, double-labeling studies localized the EBV genome to the malignant B cells. Both neoplasms contained clonal immunoglobulin gene rearrangements and clonal EBV genomes. Conclusion. Our data indicate that EBV infection was an early step in the development of these neoplasms. The findings further extend knowledge on the similarity of this subset of lymphomas to posttransplantation lymphomas and emphasize the role of immunosuppression in their genesis.     

Epstein-Barr virus, methotrexate, and lymphoma in patients with rheumatoid arthritis and primary Sjögren's syndrome: case series

OBJECTIVE: Rheumatoid arthritis (RA) and primary Sj?gren's syndrome (SS) are associated with an increased risk of lymphoma. Epstein-Barr virus (EBV), a ubiquitous herpes virus, has been linked etiologically to lymphoma in patients with RA and primary SS. Recently, methotrexate (MTX) has also been linked to the development of these lymphomas. We investigated the frequency of EBV in lymphoma tissue of patients with RA and primary SS and the association of MTX with lymphomagenesis. METHODS: Twenty-three patients with RA and 9 with primary SS with a history of lymphoma were identified by writing to all Arthritis Foundation member rheumatologists in Washington State. Formalin fixed, paraffin embedded tissue blocks were then requested from pathology laboratories. Lymph nodes from 5 RA patients without lymphoma were also studied. In situ hybridization using a biotinylated EBER-1 oligonucleotide probe was used to detect EBV in tissue sections. Positive and negative laboratory controls were used to ensure procedural integrity. RESULTS: Specimens from 21 RA patients were obtained, with 2 subsequently excluded due to specimen quality. Specimens from 6 patients with primary SS were obtained. In situ hybridization for EBV was positive in 5/19 (26%) RA patients and 1/6 patients with primary SS. In the nonmalignant lymph nodes no patient showed EBV. One primary SS and 12 RA patients were known to be taking MTX at the time of lymphoma diagnosis. Of the EBV positive RA lymphoma patients, 4/5 were receiving MTX at the time of diagnosis. These results show that EBV is present in lymphoma tissue of some patients with RA and very few with primary SS. CONCLUSION: EBV is over-represented in the lymphomas of patients with RA, but whether MTX plays a role in predisposing patients with RA and primary SS to the development of lymphoma, perhaps by influencing behavior of EBV, remains unclear.     

Immunosuppression-related lymphomas and cancers in IBD: how can they be prevented?

Most of the immunosuppressive therapy-associated excess lymphomas in IBD are due to a loss of control of Epstein-Barr virus (EBV) infection. Systemic EBV viral-load monitoring and preemptive treatments are extensively used in the posttransplant setting, but these methods have not yet been evaluated in IBD patients and cannot therefore be recommended in this context. However, the systemic EBV viral load should be measured in cases of unexplained fever, lymphadenopathy or hemophagocytic syndrome, in order to optimize the diagnostics of early EBV-related lymphoproliferations. The risk of hepatosplenic T cell lymphoma can, theoretically, be limited by avoiding prolonged combination therapy with thiopurines and anti-tumor necrosis factor (anti-TNF) beyond 2 years in young males. Young males seronegative for EBV are at risk for fatal forms of primary EBV infection, with postmononucleosis lymphoproliferation. This incidence could be limited by considering avoiding treatment with thiopurines in this subgroup of patients. There is a marked excess risk of nonmelanoma skin cancer in IBD patients currently or previously treated with thiopurines, which justifies lifelong sun protection and dermatological screening in these patients. The level of risk is still unclear for monotherapies with anti-TNF. An excess of human papilloma virus (HPV)-related uterine cervix dysplasia and cancer has been reported in various populations of women with IBD, but the proper role of immunosuppressive therapy remains to be quantified. However, yearly screening for uterine cervix abnormalities is recommended for all female IBD patients, along with HPV vaccination in young girls.     

Lymphoma in patients with rheumatoid arthritis: Association with the disease state or methotrexate treatment with the disease state or methotrexate treatment

Although long-term clinical studies have shown no excessive risk of lymphomain rheumatoid arthritis (RA) patients treated with methotrexate (MTX), an increasing number of reports of this association continue to appear. We describe two cases, review the cases in the world's literature, and summarize their important characteristics. Possible oncogenic mechanisms are discussed. Most lymphoproliferation cases presented here have features of immunosuppression-associated lymphoma. The immunosuppressed state is attributable to a combination of factors, such as RA itself and the actions of MTX. The risk factors for RA patients to develop lymphoma while on MTX include severe disease, intense immunosuppression, genetic predisposition, and an increased frequency of latent infection with prooncogenic viruses such as Epstein-Barr virus (EBV). The spontaneous remission of lymphomas in eight RA patients after MTX was stopped highlights the likely causative role of the drug in the development of these malignancies. If the clinical situation permits, a period of observation for spontaneous remission after MTX is stopped is advisable. The physicians caring for RA patients on MTX should maintain a high surveillance for signs and symptoms suggestive of lymphoma.