Does surgery belong to medical history for gastric lymphomas?

Favorable radiation field decrease in gastric marginal zone lymphoma : Experience of the German Study Group on Gastrointestinal Lymphoma (DSGL)

PURPOSE

Long-term impact of stage-adapted field reduction in a large cohort of gastric marginal zone lymphoma (gMZL) patients treated conservatively with curative radiation therapy (RT).

PATIENTS AND METHODS

Prospective analysis of paper records of 290 patients with stage IE-IIE gMZL, treated in 78 radiotherapeutic institutions in Germany from 1992-2013. Stage-adapted radiation fields decreased from extended field (EF) to involved field (IF) over the course of three consecutive prospective trials of the German Study Group on Gastrointestinal Lymphoma (DSGL). Treatment results were compared between the three cohorts.

RESULTS

Overall collective with median age of 60 years, slight male predominance (m:f = 1.1:1) and ratio of disease stage I:stage II = 2.1:1. Median follow-up 6.4 years in total: 13.0 years in the first gastrointestinal study (GIT 1992), 8.2 years in the second (GIT 1996) and 4.7 years in the third study (DSGL 01/2003). Stage-adapted radiation field decrease together with further technological development led to reduced relative frequencies of acute/chronic adverse effects and until now was accompanied by lower disease recurrence. The third study design with smallest field size (IF in stage I, locoregional EF in stage II) achieved the best survival outcome at the 5‑year follow-up (overall survival 92.7%, event-free survival 89.5% and lymphoma-specific survival 100.0%). Disease relapse observed in 10 patients. Cumulative incidence of disease-specific death was 1.7% of the followed patients. Primary disease stage associated with lymphoma-specific survival.

CONCLUSION

Stage-adapted reduction towards IF in gMZL resulted in favorable adverse effects, local control and survival rates. These results support further decreases in modern RT of gMZL.

Isolated oculomotor nerve palsy as a paraneoplastic manifestation of gastric diffuse large B-cell lymphoma: A case report

Isolated oculomotor nerve palsy (ONP) is rare. The major causes are aneurysm of the posterior communicating artery, microvascular ischemia, neoplasm, inflammation and trauma. The present study reports the case of a 72-year-old female with left isolated pupil-sparing ONP and severe anemia as the initial manifestations of gastric diffuse large B-cell lymphoma (DLBCL). Systemic chemotherapy without any central nervous system (CNS)-directed treatment led to a complete resolution of the ONP, suggesting that it was most likely to be a paraneoplastic phenomenon. If CNS involvement cannot be demonstrated by brain magnetic resonance imaging and cerebrospinal fluid assessment, the present case suggests that it may be acceptable to omit CNS-directed therapy in such cases of ONP, since it may be paraneoplastic in nature and may resolve following successful treatment of the underlying malignancy.

The many faces of marginal zone lymphoma

Indolent B-cell lymphomas that are supposed to derive from the marginal zone (marginal zone lymphomas [MZLs]) include 3 specific entities: extranodal marginal zone lymphoma (EMZL) or mucosa-associated lymphatic tissue (MALT) lymphoma, splenic MZL (SMZL), and nodal MZL (NMZL). The clinical and molecular characteristics are different for each entity, with some shared phenotypic and genetic features. EMZL is the most common entity, accounting for approximately 70% of all MZLs. These neoplasms can arise at virtually any extranodal site and are commonly associated with chronic antigenic stimulation either as a result of infection (eg, Helicobacter pylori in the stomach) or autoimmune disease (eg, Sjögren syndrome and salivary glands). Several chromosomal translocations were also identified in EMZL, accounting in the aggregate for approximately one-third of all cases. SMZL accounts for approximately 20% of all MZLs. Patients typically present with an enlarged spleen and involvement of abdominal lymph nodes and BM. Approximately 40%-50% of SMZLs are associated with deletions of chromosome 7q. NMZL is the less common entity, representing approximately 10% of all MZLs. Patients with NMZL, by definition, have lymph node–based disease without involvement of the spleen or extranodal sites. The molecular pathogenesis of NMZL is still unknown.

Long-term follow-up of localized, primary gastric diffuse large B-cell lymphoma treated with rituximab and CHOP

The addition of rituximab to cyclophosphamide, doxorubicin, vincristine and prednisone [CHOP (i.e., R-CHOP)] is considered to be the standard regimen for treating localized, primary gastric diffuse large B-cell lymphoma (PG-DLBCL). However, few studies have reported the long-term efficacy of R-CHOP therapy in the management of localized PG-DLBCL. In the present study, we performed a retrospective analysis of 11 patients with localized PG-DLBCL, who were treated with R-CHOP at Nihon University Itabashi Hospital and Kasukabe Municipal Hospital (Japan) from 2001 to 2008. Limited stage cancer was defined as stage I/II according to the Lugano staging system for gastrointestinal (GI) lymphomas. The relative dose intensity (RDI) of CHOP therapy was calculated for each patient. The median age of the patients was 68 years (range, 48-82). Gastralgia and anemia were common symptoms at initial presentation. All patients except 1 received 6 cycles of R-CHOP treatment without consolidative radiation therapy or prior surgery. RDI was maintained at over 80% in 9 out of 11 patients. All patients achieved complete remission and the estimated overall survival with a median follow-up of 54 months (range, 39-103) was 100%, without relapse or significant GI adverse effects, such as perforation or bleeding during R-CHOP treatment. No long-term adverse effects of rituximab were recorded during the observation period. Helicobacter pylori infection was diagnosed in 72.7% (8 cases) of the patients, but was eradicated in a limited number of patients. Our data suggest the feasibility and effectiveness of the addition of rituximab to conventional CHOP therapy in the management of localized PG-DLBCL.

The comparison between CHOP and R-CHOP in primary gastric diffuse large B cell lymphoma

The combination chemotherapy with cyclophosphamide, doxorubicin, vincristine, and prednisolone (CHOP) plus rituximab is the standard treatment for patients with primary gastric diffuse large B cell lymphoma (DLBCL). However, a few trials comparing CHOP plus rituximab (R-CHOP) with CHOP have been conducted in primary gastric DLBCL. Among 93 consecutive patients receiving CHOP or R-CHOP as a first-line chemotherapy at our institution, 38 patients received CHOP and 55 patients received R-CHOP. With a median follow-up time of 48 months, the complete response (CR) rate, event-free survival (EFS), and overall survival (OS) did not differ between two treatment groups (P = 1.000, P = 0.744, and P = 0.213, respectively). The CR rates were 93.9% for patients receiving CHOP and 92.5% for patients receiving R-CHOP. The 3-year EFS rates were 86.0% for patients receiving CHOP and 81.7% for patients receiving R-CHOP; the 3-year OS rates were 94.7 and 84.7%, respectively. In a multivariate analysis, The CR rate was affected by the number of extranodal involvements (P = 0.011). The EFS and OS rates were affected by the Lugano stage (P = 0.067 and P = 0.008, respectively). High serum level of β₂-microglobulin was associated with worse EFS and OS in patients receiving R-CHOP (P = 0.018 and P = 0.015, respectively). In conclusion, the addition of rituximab was not found to have an impact on patients' outcomes with primary gastric DLBCL. The β₂-microglobulin in primary gastric DLBCL might be able to discriminate the patients' prognosis who are treated with R-CHOP chemotherapy.

Retrospective analysis of primary gastric diffuse large B cell lymphoma in the rituximab era: a multicenter study of 95 patients in Japan

Primary gastric diffuse large B cell lymphoma (PG-DLBCL) is common subtype of extranodal non-Hodgkin lymphoma. The optimal treatment strategy for PG-DLBCL in the rituximab era still remains unknown. To evaluate clinical outcomes of PG-DLBCL in the rituximab era, we conducted a retrospective, multicenter analysis of 95 patients with PG-DLBCL. In 58 patients with localized disease, 3-year progression-free survival (PFS) and overall survival (OS) were 91% and 91% for patients with six cycles of rituximab plus CHOP (R-CHOP) and 92% and 95% for patients with three to four cycles of R-CHOP plus radiotherapy (Log-rank test, P = 0.595 and P = 0.278, respectively). In 37 patients with advanced disease, 3-year PFS and 3-year OS were 43% and 64% for patients with R-CHOP chemotherapy with or without radiotherapy. On multivariate analysis, advanced stage and elevated serum LDH levels were independent predictors of survival in patients with PG-DLBCL. One patient with localized disease relapsed in lymph node, and eight patients with advanced disease relapsed in lymph node (n = 3), stomach (n = 2), central nervous system (CNS; n = 2), and duodenum (n = 1). Intriguingly, CNS relapse developed within 6 months after initial series of treatment (4.9 and 5.8 months, respectively), and stomach relapse developed in later phase (27.2 and 32.9 months, respectively). Clinical outcomes of PG-DLBCL were extremely favorable for localized-stage patients in the rituximab era, although these might be poor for advanced-stage patients even in the rituximab era. Further prospective analyses are warranted.

Primary gastric diffuse large B-cell Lymphoma (DLBCL): analyses of prognostic factors and value of pretreatment FDG-PET scan

OBJECTIVES

We report a single institution experience with gastric diffuse large B-cell lymphoma (DLBCL) in an attempt to evaluate the roles of different treatment modalities, to assess the value of pretreatment positron emission tomography (PET) scan, and to identify potential prognostic factors.

METHODS

Among 384 patients diagnosed with DLBCL between 1995 and 2008, 75 patients had primary gastric DLBCL and were reviewed and analyzed.

RESULTS

The median age was 66. International prognostic index (IPI) risk was low in 52%, low-intermediate in 23%, high-intermediate in 9%, and high in 16%. Pretreatment PET scan was highly sensitive in detecting gastric lesions except stage I gastric DLBCL without detectable mass by CT or gastroscopy. As a general rule, patients with limited-stage disease were treated with three times of CHOP (with or without rituximab) and radiotherapy, and those with advanced-stage disease were treated with eight cycles of CHOP (with or without rituximab), and radiotherapy was given to residual diseases after chemotherapy. Three-year overall survival (OS) rate was 78%. Multivariate analysis revealed that low albumin, hemoglobin <12.0 g/dL, and treatment without rituximab were independently associated with shorter OS. Low albumin, hemoglobin <12.0 g/dL,and advanced stage were independently associated with shorter progression-free survival.

CONCLUSION

We showed the survival benefit of rituximab and potential prognostic value of pretreatment hemoglobin and serum albumin levels in gastric DLBCL.

Early stage gastric diffuse large B-cell lymphomas: results of a randomized trial comparing chemotherapy alone versus chemotherapy + involved field radiotherapy. (IELSG 4). [corrected]

Here, we present the results of a randomised clinical trial carried out between 1998 and 2004, evaluating the possible role of radiotherapy (RT) as consolidation treatment after induction chemotherapy (CT) in diffuse large B-cell (DLBC) gastric lymphoma. Fifty-four patients were enrolled and all received anthracycline containing regimens as induction CT. Patients were evaluated after four to six cycles and those in complete remission (CR) were randomised to receive gastric involved field (IF) RT or two addition cycles of the same CT. Forty-five patients (83%) were randomised after the induction CT. Clinical results of patients allocated to the RT arm showed a significant reduction in incidence of local relapse versus patients who received CT alone. However, overall survival was not different between the two arms. Our results confirm that CT could be considered as first line therapy for newly diagnosed gastric DLBC lymphoma; IF RT delivered in those patients achieving CR after induction CT is able to prevent local relapse.

Primary extranodal lymphomas of stomach: clinical presentation, diagnostic pitfalls and management

Gastrointestinal lymphoma is the most common form of extranodal lymphoma, accounting for 30%-40% of cases. The most commonly involved site is the stomach (60%-75% of cases), followed by the small bowel, ileum, cecum, colon and rectum. The most common histological subtypes are diffuse large B-cell lymphoma (DLBCL) and marginal zone B-cell lymphoma of the mucosa-associated lymphoid tissue (MALT). Helicobacter pylori infection has been implicated in the pathogenesis of MALT gastric lymphoma, but its role in gastric diffuse large B-cell non-Hodgkin's lymphoma (NHL) is controversial. The therapeutic approach for patients with gastric NHL has been revised over the last 10 years. Conservative treatment with anthracycline-based chemotherapy alone or in combination with involved-field radiotherapy has replaced gastrectomy as standard therapy in cases with DLBCL. Additionally, MALT lymphomas are mainly treated with antibiotics alone, which can induce lasting remissions in those cases associated with H. pylori infection. Nevertheless, various therapeutic aspects for primary gastric lymphomas are still controversial and several questions remain unanswered. Among others, the role of rituximab, consolidation radiotherapy as well as H. pylori eradication in histological aggressive subtypes warrants better clarification.

A single unit lymphoma experience: outcome in a Cape Town academic centre

To document outcome in Hodgkin and other lymphomas from a privately based academic centre the clinical records from 253 consecutive referrals were analysed. Diagnosis was according to World Health Organization criteria, prognosis assigned by the international index and therapy risk-stratified with results subject to appropriate statistical methodology. None of these patients underwent transplantation. For the cohort the median age was 55 years (range 11-94) and 63% were male. Constitutional symptoms were present in 22%; a quarter had previous chemotherapy and a third some form of irradiation prior to referral. Fifty-seven percent were stage I or II and 21% had nodal disease above and below the diaphragm whilst in the remainder cells were present in the circulation and this included the subset of chronic lymphocytic leukaemia -- small lymphocytic lymphoma. Positron emission scanning was not available for these studies. Median survival for the cohort is 3.2 years and reduced to 1.3 years by the presence of unexplained fever, sweating or inappropriate weight loss. Further adverse factors included any prior treatment, intermediate or high-grade histopathology, risk factors defined by the International Prognostic Index as well as late Rai stages. Analysed by disease category Hodgkin lymphoma (n=17) when managed according to the German Study Group protocols and hairy cell leukaemia (n=10) treated with two chlorodeoxyadenosine -- both had a stable plateau in excess of 90%. The corresponding figures for follicular variants (n=31) was 72% in the low risk and 58% in the remainder when treated with cyclophosphamide, vincristine and prednisone. Curves for the aggressive or diffuse large B-cell lymphoma (n=44) fell initially to 48%, but relapse continued in stages III and IV to the current level of 18% when receiving cyclophosphamide, hydroxydaunorubicin, vincristine and prednisone on the 21-day schedule. Chronic lymphocytic leukaemia -- small lymphocytic lymphoma (n=58) were initially given pulsed chlorambucil and sustained response was over 90% with low bulk, but declined to reach 30% as prognostic score rose. The miscellaneous categories (n<5 each) managed variably, but using the same criteria, were pooled and are presently at 62% and 30% for high and low grades. It is concluded that precise diagnosis, accurate staging and therapy on standardised risk-stratified programmes, delivered uniformly by a single multidisciplinary group, creates the all-important centre effect; matching figures are unlikely to apply outside these disciplined circumstances. The expectation from patients and referring physicians alike is that, since lymphomas are potentially curable, such an approach to comprehensive management will be regarded as standard even in an under resourced or Third World country. It follows that late referral and prior therapy will adversely affect performance status and compromise life span: These alternative approaches are inappropriate and strongly discouraged.

Primary gastric lymphoma pathogenesis and treatment: what has changed over the past 10 years?

Primary gastric (PG) lymphomas are generally non-Hodgkin lymphomas (NHL). They represent 5% of gastric malignancies and show an apparently increasing incidence worldwide. The most common histological subtypes are diffuse large B-cell and marginal zone B-cell NHL of the mucosa-associated lymphoid tissue (MALT)-type. Pathogenesis is often related to Helicobacter pylori infection (HPI). There is still no consensus on the optimal treatment for PG lymphoma. Nowadays surgery is limited to rare cases and radiotherapy--combined or not with chemotherapy--represents an effective therapeutic option ensuring long-term, organ-salvage benefits mainly in aggressive histological subtypes. Additionally, the description of MALT lymphomas has made the situation even more complex, because antibiotics alone can induce lasting remissions in those cases associated with HPI. Consequently, a global therapeutic approach to the cure of PG-NHL has completely changed over the last 10 years: innovative, conservative options to reduce treatment toxicity, thus preventing systemic relapses, have made their appearance and are on the rise.

Treatment of extranodal lymphomas

At least one-quarter of the non-Hodgkin's lymphomas arise primarily at extranodal sites. The rising incidence of non-Hodgkin's lymphomas, observed over recent decades, have mainly affected the primary extranodal entities. Survival rates vary among the specific sites of primary extranodal lymphomas. This is due partly to differences in natural history, related mainly to the histological type but also to differences in management strategy which are related to organ-specific problems. Few controlled studies facilitate therapeutic decisions in this setting. This chapter represents a general overview of the available data.

Comparison of MALT and non-MALT primary large cell lymphoma of the stomach: does histologic evidence of MALT affect chemotherapy response?

BACKGROUND

Although the clinicopathologic features of low grade gastric MALToma (lymphoma of mucosa-associated lymphoid tissue) recently have been well delineated, the significance of identifying histologic evidence of MALT origin in a primary high grade gastric lymphoma is less clear. The authors sought to address this issue and, in particular, to clarify if MALT and non-MALT primary large cell gastric lymphoma might have a different response to systemic chemotherapy.

METHODS

The authors reviewed the pathologic specimens of all patients who had a diagnosis of primary large cell lymphoma of the stomach and who had been treated primarily by systemic chemotherapy in our institutions January 1, 1988-December 31, 1998. The patients were divided into two groups by experienced hematopathologists, based on the presence or absence of histologic features suggestive of MALToma, including typical lymphoepithelial lesions and infiltration of characteristic centrocyte-like cells. Disease staging was done according to the AJCC/UICC system with Musshoff modification. The median number of gastric biopsies for each patient was 7 (range, 1-21).

RESULTS

Seventeen patients with and 26 patients without histologic evidence of MALToma were identified. Clinical features were similar between the two groups except that a greater proportion of patients without evidence of MALToma had elevated levels of serum lactate dehydrogenase (50% vs. 12%, P = 0.01). The median duration of follow-up for the 43 patients was 46.5 months (range, 17-124 mos). All patients received standard systemic chemotherapy including anthracyclines or anthracenedione. The response rate was 88.2% for patients with evidence of MALToma and 57.7% for those without (P = 0.03). The 5-year overall survival rate was 80.5% for patients with evidence of MALToma and 48.9% for those without (P = 0.02). Multivariate analysis indicated that response to chemotherapy, disease stage (Stage I and II-1 vs. Stage II-2, III, and IV), and the presence of MALToma features were independent prognostic factors for overall survival.

CONCLUSION

The results of this relatively small study series suggested that the presence of histologic features of MALToma in patients with primary large cell gastric lymphoma might have been associated with a better response to systemic chemotherapy and a better prognosis. Further studies to consolidate this conclusion are necessary.

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.

Primary gastric non-Hodgkin's lymphoma: clinical features, management, and prognosis of 185 patients with diffuse large B-cell lymphoma

BACKGROUND

Primary gastric non-Hodgkin's lymphoma (PG-NHL) is common in Saudi Arabia. This has prompted the analysis of a large series of patients with PG-NHL having high-grade diffuse large B-cell lymphoma (DLCL) in order to define the clinical features and outcome of this disease.

PATIENTS AND METHODS

The data of all adult patients in the series with PG-NHL having DLCL histology were retrospectively reviewed. Patients were eligible if they had biopsy-confirmed diagnoses obtained by endoscopy or following laparotomy.

RESULTS

Over a 16-year period, 185 patients with DLCL PG-NHL were identified and their data were reviewed. Patients had a median age of 54 years. In 53% of them only one initial therapeutic modality was given, while 47% were managed by a multi-modality approach. One hundred forty patients (76%), 19 (10%), and 26 (14%) attained complete remission (CR), partial remission, and no response/progressive disease, respectively. Multivariate analysis showed that poor performance status and advanced stage were negatively associated with the likelihood of attaining CR. Over a median follow-up of 54 months, 118 (64%) of the patients were alive and disease-free, 17 (9%) were alive with evidence of disease, and the remaining 50 (27%) were dead. The projected 5-year and 10-year overall survivals (OS) (+/- SD) were 68% (+/- 4%) and 61% (+/- 6%), respectively. The Cox proportional hazards model identified the same variables of response as adverse prognostic factors of survival. Using the influence of performance status, and stage, a prognostic index was constructed to recognize three prognostically distinctive risk categories with overall survival proportions of 87%, 61%, and 45%, respectively. The unadjusted International Prognostic Index, however, failed to classify patients into prognostically meaningful risk strata. Of the 140 patients who achieved CR, the median disease-free survival (DFS) was not reached, but the predicted 5- and 10-year DFS were 82% and 75%, respectively. A multivariate analysis identified poor performance status as the only independent prognostic covariate that adversely influenced DFS. Our analysis showed that compared with single-modality management, multi-modality strategy attained significantly higher CR, and advantageous OS and DFS.

CONCLUSIONS

This large series characterized the clinico-pathologic features and outcome of patients with DLCL PG-NHL. Performance status, and stage significantly influenced patient outcome. A prognostic index was developed and it identified three prognostically distinctive risk groups; however, prospective validation is warranted.

Stage-modified international prognostic index effectively predicts clinical outcome of localized primary gastric diffuse large B-cell lymphoma. International Extranodal Lymphoma Study Group (IELSG)

BACKGROUND

The definition of prognostic parameters in early stages of gastric lymphoma is still controversial. The aim of this retrospective analysis was to assess the value of the stage-modified international prognostic index (IPI) in predicting the outcome of a large, consecutive series of patients with PGL of diffuse large B-cell histology (DLCL).

PATIENTS AND METHODS

Three hundred twelve consecutive, newly-diagnosed, patients with localized PGL (stages I-IIE according to the 'Lugano staging system for GI lymphomas') referred from April 1972 to December 1997 to eight Italian and one Swiss centers were reviewed and their outcomes updated to June 1998. One hundred three patients were treated with single-modality therapy, while two hundred four received combined-modality treatment, most of which included surgery and short-term chemotherapy.

RESULTS

After a median follow-up of 66 months (range 0.6-300 months), 195 (64%) were alive in first continuous complete remission (CCR). The five-year estimates of overall survival (OS) and event-free survival (EFS) were 75% and 67%, respectively. OS and EFS varied according to IPI, from, respectively, 90% and 82% for patients with 0-1 risk factors, to 40% and 35% for patients with > or = 3 risk factors (P = 0.00001). Cox regression analysis showed that IPI was the strongest predictor of survival.

CONCLUSIONS

This study shows that stage-modified IPI is an effective predictive model in patients with primary DLCL of the stomach, enabling identification of patients with significantly different outcomes.

Evaluation and management of the "new" lymphoma entities: mantle cell lymphoma, lymphoma of mucosa-associated lymphoid tissue, anaplastic large-cell lymphoma, and primary mediastinal B-cell lymphoma

Non-Hodgkin's lymphomas (NHL) represent a major health problem worldwide, and incidence has been on the rise continuously for the last few decades. It is estimated that approximately 55,000 new cases of NHL will be diagnosed in the United States in 1998 and that slightly fewer than 25,000 patients will die of treatment failure or recurrent disease. The rising incidence of NHL is related not only to the acquired immunodeficiency syndrome epidemic but to also a steady increase in the number of cases diagnosed in older patients without immunosuppression. The new pathologic classification of NHL (revised European-American lymphoma classification, REAL) developed by the International Lymphoma Study Group (ILSG) is already resulting in more accurate disease-specific epidemiologic and clinical investigations. These studies have brought a new awareness of the existence and the relative prevalence of discrete NHL subtypes that appear to predominate among patients in different populations according to age, sex, geographic distribution, and predisposing conditions. This developing database has also the potential to result in the discovery of specific environmental causes, predisposing genetic factors, and therapeutic approaches. Some of the entities defined in the REAL classification, such as follicular lymphomas, diffuse B large-cell lymphomas, and T-cell lymphoblastic lymphomas, were already well described in the older classification systems (Kiel and Working Formulation). Others, such as mantle cell lymphoma, (MCL) anaplastic large-cell lymphoma (ALCL), lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma), and primary mediastinal B-cell lymphoma (PMBCL) are relatively new members of the family, and accurate data on their clinicopathologic features and natural histories have only recently begun to emerge. This review presents in detail the most recent data on the clinical presentation of, diagnostic evaluation of, and treatment options for the most common of the new NHL entities: MCL, MALT lymphoma, CD30+ (Ki-1+) ALCL, and PMBCL. These four entities combined represent approximately 20% of all cases of NHL and exemplify well the broad clinicopathologic spectrum of NHL and the diagnostic and therapeutic challenges facing those who care for patients affected by these conditions.