Stage II large B-cell lymphoma with sclerosis treated with MACOP-B

Improved survival for dose-intensive chemotherapy in primary mediastinal B-cell lymphoma: a systematic review and meta-analysis of 4,068 patients

Primary mediastinal B-cell lymphoma (PMBCL) is a distinct clinicopathologic entity. Currently, there is a paucity of randomized prospective data to inform on optimal front-line chemoimmunotherapy (CIT) and use of consolidative mediastinal radiation (RT). To assess if distinct CIT approaches are associated with disparate survival outcomes, we performed a systematic review and meta-analysis comparing dose-intensive (DI-CIT) versus standard CIT for the front-line treatment of PMBCL. Standard approach (S-CIT) was defined as R-CHOP-21/CHOP-21, with or without RT. DI-CIT were defined as regimens with increased frequency, dose, and/or number of systemic agents. We reviewed data on 4,068 patients (2,517 DI-CIT; 1,551 S-CIT) with a new diagnosis of PMBCL. Overall survival for DI-CIT patients was 88% (95% CI: 85-90) compared to 80% for the S-CIT cohort (95% CI: 74-85). Meta-regression revealed an 8% overall survival (OS) benefit for the DI-CIT group (P<0.01). Survival benefit was maintained when analyzing rituximab only regimens; OS was 91% (95% CI: 89-93) for the rituximab-DI-CIT arm compared to 86% (95% CI: 82-89) for the R-CHOP-21 arm (P=0.03). Importantly, 55% (95% CI: 43-65) of the S-CIT group received RT compared to 22% (95% CI: 15-31) of DI-CIT patients (meta-regression P<0.01). To our knowledge, this is the largest meta-analysis reporting efficacy outcomes for the front-line treatment of PMBCL. DI-CIT demonstrates a survival benefit, with significantly less radiation exposure, curtailing long-term toxicities associated with radiotherapy. As we await results of randomized prospective trials, our study supports the use of dose-intensive chemoimmunotherapy for the treatment of PMBCL.

Primary Mediastinal B-Cell Lymphoma: A 2021 Update on Genetics, Diagnosis, and Novel Therapeutics

Primary mediastinal large B-cell lymphoma (PMBCL) is an aggressive B-cell lymphoma arising from thymic B-cells having clinicopathologic features distinct from systemic diffuse large B-cell lymphoma (DLBCL). PMBCL comprises 2% to 4% of all non-Hodgkin lymphomas (NHL), 7% of DLBCL and seen predominantly in young females with a median age of 35 years at diagnosis. The annual incidence of PMBCL is 0.4 per million with a 5-year survival rate exceeding 70% with improving supportive care and genetic characterization of the disease. Pathogenesis involves dysregulation of Janus kinase-signal transducer and activator of transcription (JAK-STAT), nuclear factor-kB (NF-kB) pathways and amplification of the 9p24.1 region of chromosome 9. PMBCL patients have a prolonged life expectancy necessitating the need for treatment approaches that are based on maximizing cure with minimal long-term toxicity. Due to rarity and its recognition as a distinct entity, therapeutic decisions are guided by clinical presentation, clinician and center experience, and analysis of patients with PMBCL within DLBCL registries. Historically R-CHOP has been the usual first line treatment for PMBCL followed by involved site radiotherapy (ISRT), however clinical practice varies across centers with emerging consensus to avoid upfront RT by utilizing dose intense regimens (DA-EPOCH-R) in younger and fit patients. Prognosis of relapsed refractory PMBCL not responding to salvage chemotherapy is dismal, however there are many emerging options including Brentuximab Vedotin, immune check point inhibitors and chimeric antigen receptor T-cell therapy. In this article, we focus on the pathogenesis, current and evolving treatments, and provide recommendations for optimal management of patients with PMBCL.

How I treat primary mediastinal B-cell lymphoma

The World Health Organization now recognizes primary mediastinal B-cell lymphoma (PMBCL) as a unique clinical and biologic entity. PMBCL is distinct from other B-cell non-Hodgkin lymphoma subtypes and has features that overlap with classical Hodgkin lymphoma, including a peak incidence in the adolescent and young adult population, mediastinal presentation of disease, and molecular alterations in JAK2 and programmed death ligands. Because PMBCL is rare, there are few prospective clinical trials to guide therapy, resulting in no single standard of care. Given the long life expectancy of survivors of PMBCL, treatment approaches must balance maximizing cure while minimizing long-term toxicity. In this article, I review my approach to the treatment of PMBCL, incorporating data from adult and pediatric studies, as well as recent advances in our understanding of the molecular basis of PMBCL.

Optimizing Outcomes in Primary Mediastinal B-cell Lymphoma

Primary mediastinal B-cell lymphoma is characterized by a high chance of cure, and cured patients have a long disease-free life-expectancy; however, prognosis is severe in the case of relapsed or refractory disease. The initial use of the most effective chemoimmunotherapy regimen is therefore crucial. Understanding who will benefit from postinduction radiotherapy is also of paramount importance; positron emission tomography may be a reliable guide for physicians in determining which patients will require consolidation. New drugs with mechanisms of action including the most relevant biologic features of the tumor may allow better disease control.

The treatment of primary mediastinal large B-cell lymphoma: a two decades monocentric experience with 98 patients

Background

The purpose of this study is to investigate the most suitable first-line approach and the best combination treatment for primary mediastinal large B-cell lymphoma (PMLBCL) as they have been matter of debate for at least two decades.

Methods

Our single centre experience in the treatment of 98 de novo PMLBCL patients over the last 20 years is reviewed. All patients received MACOP-B chemotherapy. Thirty-seven received both rituximab and mediastinal radiotherapy; 30 were irradiated after chemotherapy, although not receiving rituximab and 20 received rituximab without radiotherapy consolidation. Eleven patients received chemotherapy only.

Results

Sixty-one (62.2%) patients achieved a complete response after MACOP-B (with or without rituximab); among the 27 (27.6%) partial responders, 21 obtained a complete response after radiotherapy. At the end of their scheduled treatment, 82 patients (83.7%) had a complete and 6 a partial response (6.1%). Eleven patients relapsed within the first 2 years of follow-up. The 17-year overall survival is 72.0% (15 patients died); progression-free and disease-free survival are 67.6% and 88.4%, respectively. A statistically significant difference in overall and progression-free survival was noted among treatment groups, although no disease-free survival difference was documented.

Conclusions

Our data indicate that a third-generation regimen like MACOP-B could be considered a suitable first-line treatment. Mediastinal consolidation radiotherapy impacts on survival and complete response rates and remains a good strategy to convert partial into complete responses. Data suggest that radiotherapy may be avoided in patients obtaining a complete response after (immuno)chemotherapy, but this requires confirmation with further ad hoc studies.

Current trends in the treatment of primary mediastinal large B-cell lymphoma - an overview

Primary mediastinal large B-cell lymphoma has been recognised as a distinct entity with unique clinical, pathologic, and genetic features. According to WHO 2008 classification it is marked as a variant of diffuse large B-cell lymphoma but shares characteristics with classic Hodgkin lymphoma. Genetic analysis has shown that amplification of the 9p24.1 region is the disease's specific structural alteration. Aggressive behaviour and a tendency to invade surrounding tissues of the thoracic cavity, often causing superior vena cava syndrome, or pleural or pericardial effusions, are the clinical hallmarks of this disease. For a long period of time it has been considered as a disease with poor prognosis, which responds poorly to the conventional treatment created for diffuse large B-cell lymphoma. An elective treatment has not yet been established, but recently the situation has became much more favourable. After the introduction of rituximab the cure rates have risen to over 80%, and the most recent results have demonstrated a new insight with dose-adjusted intensified continuous treatments, in which the cure rates have exceeded 90%. Current trends have led to the introduction of dose-adjusted intensified protocols becoming a standard of care, whereas the use of radiotherapy remains controversial because of the questionable predictive value of post-treatment PET/CT validity. The relapse rate is very low after two years of sustained complete remission. If the disease relapses or is resistant the outcome is very poor regardless of the applied treatment modality.

Primary mediastinal DLBCL: evolving biologic understanding and therapeutic strategies

Primary mediastinal diffuse large B-cell lymphoma is a quite rare clinicopathologic entity. Molecular analysis shows it to be distinct from other types of diffuse large B-cell lymphoma, and some retrospective analyses suggests that it may respond better to third-generation chemotherapy regimens than to the more commonly used CHOP. The addition of rituximab could reduce these differences; the role of consolidation with local radiotherapy, which is often used to treat residual mediastinal masses, remains. The real role of FDG-PET scanning requires prospective studies, and it is hoped that this may allow the de-escalation of radiation therapy accordingly to yield reliable prognostic information.

Rituximab combined with MACOP-B or VACOP-B and radiation therapy in primary mediastinal large B-cell lymphoma: a retrospective study

BACKGROUND

Third-generation regimens (MACOP-B [methotrexate/leucovorin (LV)/doxorubicin/cyclophosphamide/vincristine/ prednisone/bleomycin] or VACOP-B [etoposide/LV/doxorubicin/cyclophosphamide/vincristine/prednisone/bleomycin]) in combination with local radiation therapy seem to improve lymphoma-free survival of primary mediastinal large B-cell lymphoma (PMLBCL). Recently, the superiority of R-CHOP (rituximab plus cyclophosphamide/doxorubicin/vincristine/ prednisone) over CHOP-like regimens has been demonstrated in elderly and younger patients with low-risk diffuse large B-cell lymphoma.

PATIENTS AND METHODS

Retrospectively, between February 2002 and July 2006, 45 previously untreated patients with PMLBCL were treated with a combination of a third-generation chemotherapy regimen (MACOP-B or VACOP-B), concurrent rituximab, and mediastinal radiation therapy.

RESULTS

Twenty-six (62%) patients achieved a complete response (CR), and 15 (36%) obtained a partial response after MACOP-B/VACOP-B plus rituximab. After radiation therapy, the CR rate was 80%. At a median follow-up of 28 months, among the 34 patients who obtained a CR, 3 relapsed after 16, 19, and 22 months, respectively. Projected overall survival was 80% at 5 years; the relapse-free survival (RFS) curve of the 34 patients who achieved CR was 88% at 5 years.

CONCLUSION

In this retrospective study, in patients with PMLBCL, combined-modality treatment using the MACOP-B/VACOP-B regimen plus rituximab induces a high remission rate, with patients having a > 80% chance of surviving relapse free at 5 years. In comparison with historical data on MACOP-B/VACOP-B without rituximab, there are no statistically significant differences in terms of CR and RFS rates.

Primary mediastinal B-cell lymphoma: treatment and therapeutic targets

Primary mediastinal B-cell lymphoma (PMBCL) is a recognised subtype of diffuse large B-cell lymphoma according to the WHO classification that represents approximately 5% of aggressive lymphomas, and 2% of all cases of lymphomas. It presents with unique clinical, morphologic and immunophenotypic characteristics that define the disease. Retrospective studies have found that PMBCL patients have excellent survival rates with a distinct plateau and a trend to better outcome if treated with dose-intensified chemotherapy with MACOPB or VACOPB. In spite of the multiple molecular data known, generated on the pathogenesis of this tumour, treatment is still essentially based on a combination of chemo and immunotherapy. We take this opportunity for reviewing the recent biologic data provided by gene expression profiling of the tumour, for discussing new potential therapeutic targets.

Primary mediastinal large B-cell lymphoma: optimal therapy and prognostic factor analysis in 141 consecutive patients treated at memorial Sloan Kettering from 1980 to 1999

Primary mediastinal large B-cell lymphoma (PMLBL) is a distinct clinicopathological entity with unclear prognostic factors and optimal treatment approach. To elucidate an optimal treatment and identify predictive factors, a retrospective analysis of 141 consecutive patients was undertaken. Patients received cyclophosphamide, hydroxydaunomycin, Oncovin, prednisone (CHOP)-like therapy, the non-Hodgkin lymphoma (NHL)-15 regimen or upfront autologous stem cell transplantation (ASCT) on Institutional Review Board approved trials or according to the institutional guidelines. Evaluation included lactate dehydrogenase, International Prognostic Index (IPI) assessment, computed tomography scan and gallium imaging. With a median follow-up of 10.9 years, event-free survival (EFS) and overall survival (OS) was 50% and 66% respectively. EFS/OS for CHOP/CHOP-like, NHL-15 and upfront ASCT was 34/51%, 60/84% and 60/78% respectively. CHOP/CHOP-like regimens had inferior EFS and OS versus NHL-15 or upfront ASCT (P < 0.001). A total of 23% of patients received radiotherapy. Multivariate analysis revealed the following outcome predictors: for EFS, greater than or equal to two extranodal sites and initial therapy received (NHL-15 or upfront ASCT); for OS, only initial therapy with NHL-15. We conclude: (i) dose-dense chemotherapy with NHL-15 may be superior to CHOP for PMLBL; (ii) The impact of consolidative radiotherapy requires randomised controlled trials; (iii) The age-adjusted IPI did not predict survival in this analysis; (iv) high-dose chemotherapy/ASCT should be reserved for upfront anthracycline-based therapy failure or in clinical trials for high-risk patients.

Primary mediastinal large B-cell lymphoma: clinical study of a distinct clinical entity and treatment outcome in 20 patients: review of the literature

Primary mediastinal B-cell lymphoma (PMBCL) is a discrete subset of large B-cell lymphoma with unique clinicopathologic features. The question of optimal treatment emerges because it is an uncommon but not rare occurrence. A retrospective study was therefore conducted in a group of patients in Greece to evaluate the clinical features and treatment outcome in this disease. Twenty patients with PMBCL, with a median age of 42 years, treated at centers participating in the Hellenic Cooperative Oncology Group over the last 20 years, were reviewed. Thirteen (65%) had bulky disease at the time of presentation, 7 (35%) had superior vena cavae obstruction, and 15 (75%) had extranodal involvement. All received doxorubicin-containing chemotherapy, followed in 11 cases by mediastinal radiotherapy. With a median follow-up of 91 months, the median survival is 67.7 months. These data are consistent with those reported from other centers concerning the patient's characteristics, natural history, response pattern to chemoradiation therapy, and prognosis. Response to therapy proved of prognostic significance. A key question that remains is the prompt identification of patients who would benefit from innovative or more intensive therapies.

Primary mediastinal large B-cell lymphoma (PMLBCL): long-term results from a retrospective multicentre Italian experience in 138 patients treated with CHOP or MACOP-B/VACOP-B

The optimal treatment of primary mediastinal large B-cell lymphoma (PMLBCL) is still undefined. In the absence of randomised studies, we retrospectively analysed: (a) the effectiveness of two chemotherapy regimens (CHOP vs MACOP-B/VACOP-B) in complete remission (CR) achievement and event-free survival (EFS) and (b) the role of mediastinal involved-field radiotherapy (IF-RT) as consolidation. From 1982 to 1999, 138 consecutive patients affected by PMLBCL were treated in 13 Italian institutions with CHOP (43) or MACOP-B/VACOP-B (95). The two groups of patients were similar as regard to age, gender, presence of bulky mediastinal mass, pleural effusion, stage and international prognostic indexes category of risk. Overall, 75.5% of patients in CR received IF-RT as consolidation. Complete remission was 51.1% in the CHOP group and 80% in MACOP-B/VACOP-B (P<0.001). Relapse occurred in 22.7% of CHOP- and in 9.2% of MACOP-B/VACOP-B-treated patients (n.s.). Event-free patients were 39.5% in CHOP and 75.7% in the MACOP-B/VACOP-B group (P<0.001). The addition of IF-RT as consolidation improved the outcome, irrespectively of the type of chemotherapy (P=0.04). At a multivariate analysis, achievement of CR (P<0.0001) and type of CT (MACOP-B/VACOP-B) retained the significance for OS (P=0.008) and EFS (P=0.03). In our experience, MACOP-B/VACOP-B appears to positively influence OS and EFS in patients affected by PMLBCL, as compared to CHOP. Consolidation IF-RT on mediastinum further improves the outcome of CR patients.

Primary mediastinal B-cell lymphoma: a review of pathology and management

PURPOSE

Primary mediastinal B-cell lymphoma (PMBL) is recognized as a separate disease entity in the REAL classification. There is uncertainty about the relevance and especially the optimal management of this disorder. In this review, we discuss clinical presentation, pathology, pathobiology, and management of PMBL in order to provide a platform for initiation of further clinical and biologic studies.

MATERIALS AND METHODS

Studies were identified through a MEDLINE search and from the bibliographies of relevant articles.

RESULTS

PMBL is a tumor of young adults who present with a rapidly proliferating tumor. At diagnosis, the tumor is usually limited to intrathoracic organs. Spread to parenchymal organs such as liver, kidneys, and CNS is common at recurrence. Fibrosis and the presence of so-called clear cells are distinctive morphologic features of PMBL, although they are not pathognomonic or even necessary for diagnosis. On the other hand, biologic features relating to oncogene rearrangement and overexpression as well as cytogenetic features clearly differentiate PMBL from other types of diffuse large B-cell lymphoma. Phase II studies and retrospective series indicate cure rates that range from 38% to 88%. The role of chemotherapy, radiation, and high-dose chemotherapy with stem cell rescue in the management of PMBL is reviewed.

CONCLUSION

PMBL has unique clinical and biologic characteristics that are radically different from those of other types of diffuse large B-cell lymphoma. Although relatively rare, its aggressive growth and its occurrence in young patients increase the clinical relevance of this entity. The consistent recognition and study of PMBL will allow the development of new approaches to its management.

Treatment and Clinical Management of Primary Mediastinal Large B-Cell Lymphoma With Sclerosis: MACOP-B Regimen and Mediastinal Radiotherapy Monitored by 67Gallium Scan in 50 Patients

To evaluate the efficacy of a combined modality treatment (MACOP-B plus mediastinal radiotherapy) and the advantages of Gallium-67-citrate single-photon emission (67GaSPECT) over computed tomography (CT) for restaging in patients with primary mediastinal large B-cell lymphoma (PMLBCL) with sclerosis. Between 1989 and 1998, 50 previously untreated patients with PMLBCL with sclerosis (70% with bulky mass) were treated with MACOP-B regimen plus mediastinal radiotherapy. The radiologic clinical stage with evaluation of tumor size included CT and 67GaSPECT at diagnosis, after chemotherapy, and after radiotherapy. Forty-three patients (86%) achieved a complete response and 7 were nonresponders to treatment. For the imaging evaluation, only 47 patients were evaluable because 3 had disease progression during chemotherapy. After treatment, 3/5 (60%) patients with positive 67GaSPECT and negative CT scan relapsed, as against 0/21 (0%) with negative 67GaSPECT and CT scan. Twenty-one patients had a positive CT scan: of these, the 4 with positive 67GaSPECT all progressed, whereas there were no relapses among the 17 with negative 67GaSPECT. After radiotherapy, there was a decrease of positive CT (from 33 to 21 cases) and of positive 67GaSPECT (from 31 to 9 cases). Relapse-free survival rate was 93% at 96 months (median 39 months). In patients with PMLBCL with sclerosis, MACOP-B plus radiation therapy is a very useful first-line treatment and radiation therapy may play an important role. As regards restaging, 67GaSPECT should be considered the imaging technique of choice at least in patients who show CT positivity.

Primary mediastinal large B-cell lymphoma: the need for prospective controlled clinical trials

Primary mediastinal large-B cell lymphomas (PMLCL) are considered to be a distinct clinicopathologic entity among the diffuse large B-cell lymphomas. This study evaluated the prognostic factors and therapeutic outcome of PMLCL in a single-institution series. Twenty seven patients were reviewed. Nineteen of the 27 had Stage I-II and 8 had Stage III-IV disease. B-symptoms were found in 11 (41%) and bulky disease in 10 (37%) patients. All were initially given combination chemotherapy (CT): doxorubicin-containing regimens to 23 patients (11 patients had CHOP, 12 received more intensive third-generation regimens) and 4 elderly (>70 years) patients received CVP. Eleven responders were consolidated with irradiation (RT) as part of their initial treatment, with a median total dose of 39 Gy. Nineteen patients (70%) achieved clinical remission (15 CR and 4 PR) with their initial therapy. Forty-four percent of patients remained progression-free and 59% are alive at 3 years. The actuarial 10-year time to progression (TTP) and overall survival (OS) were 44% and 50%, respectively. Age >60 years, performance status >1 and IPI intermediate-high to high risk were significantly associated with poorer OS and TTP by univariate analysis (log-rank test). A better outcome was associated with the use of more aggressive chemotherapy regimens or with the inclusion of RT in the first-line treatment. Our analyses suggest that the application of radiotherapy in combination regimens and the use of more aggressive chemotherapy in the treatment of this particular type of lymphoma should now be evaluated in prospective randomized trials.

Primary mediastinal large B-cell lymphoma (PMLCL): the need for prospective controlled clinical trials

Primary mediastinal large-B cell lymphomas (PMLCL) are considered to be a distinct clinicopathologic entity among the diffuse large B-cell lymphomas. This study evaluated the prognostic factors and therapeutic outcome of PMLCL in a single-institution series. Twenty seven patients were reviewed. Nineteen of the 27 had Stage I-II and 8 had Stage III-IV disease. B-symptoms were found in 11 (41%) patients and bulky disease in 10 (37%). All patients were initially given combination chemotherapy (CT): doxorubicin-containing regimens to 23 patients (11 patients had CHOP, 12 more intensive third-generation regimens) and 4 elderly (>70 years) patients received CVP. Eleven responders were consolidated with irradiation (RT) as part of their initial treatment, with a median total dose of 39 Gy. Nineteen patients (70%) achieved clinical remission (15 CR and 4 PR) with their initial therapy. Forty-four percent of patients remained progression-free and 59% are alive at 3 years. The actuarial 10-year TTP and OS were 44% and 50%, respectively. Age >60 years, performance status >1 and IPI intermediate-high to high risk were significantly associated with poorer OS and TTP by univariate analysis (log-rank test). A better outcome was associated with the use of more aggressive chemotherapy regimens or with the inclusion of RT in the first-line treatment. In conclusion our analyses suggest that the application of radiotherapy in combination regimens and the use of more aggressive chemotherapy in the treatment of this particular lymphoma entity should be evaluated in prospective randomized trials.

CNS involvement in primary mediastinal large B-cell lymphoma

PURPOSE

The risk of CNS involvement by non-Hodgkin's Lymphoma (NHL) has been associated with bone marrow and/or testicular involvement; however, it was recently reported that the number of extranodal sites is a more reliable predictor of CNS disease. Because primary mediastinal thymic large B-cell lymphoma (PMLCL) has a high propensity for involving extranodal sites, we investigated the frequency and pattern of CNS involvement in PMLCL.

PATIENTS AND METHODS

The medical records of 219 patients with aggressive NHL, consecutively entered onto protocols at the National Cancer Institute between 1987 and 1998, were retrospectively reviewed.

RESULTS

Twenty-three patients (11%) had clinical and pathologic features of PMLCL. These patients were young (median age, 29 years), female (61%), and presented with massive mediastinal adenopathy (70%). Extranodal disease occurred at presentation in 70% and at relapse in 93% of patients and involved contiguous intrathoracic structures and/or distant sites, including the lungs, kidneys, liver, adrenals, ovaries, pancreas, and bone. Six patients (26%) developed CNS involvement, two (9%) at presentation and four (27%) at relapse. All had extranodal disease, but only one had bone marrow involvement. Parenchymal and leptomeningeal CNS disease occurred in four and three patients, respectively.

CONCLUSION

CNS involvement in PMLCL is associated with extranodal involvement other than bone marrow and may reflect the unique biology of this disease. The propensity to involve the CNS parenchyma raises the concern that intrathecal prophylaxis may not be effective and suggests that CNS imaging should be considered in patients with extranodal disease.

Primary mediastinal large B-cell lymphoma: a clinicopathologic study of 43 patients from the Nebraska Lymphoma Study Group

PURPOSE

To investigate whether primary mediastinal large B-cell lymphoma (PMLBL) is a distinct clinicopathologic entity with a more aggressive course than other diffuse large B-cell lymphomas (DLBL).

MATERIALS AND METHODS

All patients with CD20-positive DLBL who presented with a mediastinal mass measuring at least 5.0 cm and were treated with curative intent were identified. A control group of 352 patients with nonmediastinal DLBL was selected for comparison.

RESULTS

The 43 patients with PMLBL had a male to female ratio of 20:23 and a median age of 42 years. Stage I/II disease was present in 58% of the patients, with only 9% having bone marrow involvement. A complete remission was achieved in 63% of the patients, and the 5-year overall and failure-free survivals were 46% and 38%, respectively. Among the clinical variables, an elevated serum lactate dehydrogenase level, a low performance score, more than one extranodal site, and an intermediate or high International Prognostic Index score were predictive of poor survival. When compared with the DLBL group, a younger median age was the only clinical feature that was significantly different in the PMLBL group.

CONCLUSION

The clinical features of PMLBL do not appear to be significantly different from those of nonmediastinal DLBL. Although the younger age of onset, slight female predominance, mediastinal location, and size of the mass may justify the recognition of PMLBL as a clinical syndrome, additional evidence is needed to define it as a distinct disease entity.

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.

MACOP-B and involved field radiation therapy is an effective therapy for primary mediastinal large B-cell lymphoma with sclerosis

PURPOSE

To evaluate the clinical features of presentation and the response to two different third-generation regimens (F-MACHOP and MACOP-B) of primary mediastinal large B-cell lymphoma (MLBCL), a recently defined distinct clinicopathological entity of non-Hodgkin's lymphoma (NHL).

PATIENTS AND METHODS

Thirty-seven consecutive patients with MLBCL, eight male and 29 female (F/M ratio 1:3.5) with a median age of 35 years, were enrolled in the present study. Thirty-five (94.5%) patients presented disease confined to thorax, with chest symptoms of a rapidly enlarging mass in the mediastinum in 70% and superior vena cava syndrome (SCVS) in 43% of these patients. The first 10 patients received F-MACHOP and the succeeding 27 patients MACOP-B chemotherapy, associated in 24 (88.8%) with involved field radiation therapy (IFRT). 67Gallium scan was routinely performed pre- and post-IFRT in 18 patients.

RESULTS

All 37 patients were assessable for response: 10 of 10 (100%) in the F-MACHOP and 26 of 27 (96.3%) in the MACOP-B group achieved overall responses (CR + PR). Three of 24 (12.5%) patients in PR after chemotherapy obtained CR after IFRT. Persistent Gallium avidity was observed in 16 patients after chemotherapy and in only four patients after IFRT. Thus far, four of the 10 F-MACHOP and two of the 26 MACOP-B responders have presented disease progression. The probability of progression-free survival (PFS) was 91% and 60% (P < 0.02) while overall survival (OS) was 93% and 70% (P = n.s.) at a mean follow-up of 27 and 52 months in the MACOP-B + IFRT and F-MACHOP groups, respectively.

CONCLUSION

MACOP-B + IFRT has proved to be a highly effective and less toxic therapeutic approach for primary MLBCL and appears to be superior to other third-generation chemotherapy regimens.

Mediastinal large-cell lymphoma with sclerosis refractory to conventional chemotherapy can respond after daily oral cyclophosphamide

Mediastinal large-cell lymphoma with sclerosis (MLCLS) is a distinctive subtype of non-Hodgkin's lymphoma (NHL) with unique clinicopathology aspects and aggressive behavior. Prompt diagnosis and aggressive chemotherapy followed by consolidation radiotherapy may result in long-term survival in the majority of cases. However, a subset of patients do not respond to first-line or salvage treatment and have a poor prognosis. We report here a 27-year-old man with MLCLS resistant to several conventional chemotherapies and to radiotherapy who achieved a very good partial remission after one year's treatment with daily oral cyclophosphamide (100 mg/day). This is the first report of refractory MLCLS with good response to daily oral cyclophosphamide. This case suggests that daily oral monochemotherapy might be beneficial for some patients with mediastinal large-cell lymphoma with sclerosis refractory to conventional intravenous chemotherapies and radiotherapy.

Use of the international prognostic index and the tumor score to detect poor-risk patients with primary mediastinal large B-cell lymphoma: a study of 37 previously untreated patients

We tested two prognostic models devised for intermediate-grade lymphomas, the age-adjusted international prognostic index and the tumor score, in 37 consecutive untreated patients treated for a diagnosis of primary mediastinal large B-cell lymphoma (PMLCL). Neither model selected for a group of patients with statistically significant differences in rates of complete response, failure-free survival (FFS) and overall survival (OS). Because the level of beta microglobulin (beta2m) is consistently low in the serum of patients with PMLCL despite bulky disease, we tested the median value of this continuous variable in the 37 patients and found it to be statistically significant for predicting FFS. A hypothetical tumor score model using the adjusted value for beta2m improved the prognostic accuracy for achievement of complete response (93% vs. 60%; P = 0.02), FFS (73% vs. 35%; P = 0.02), and OS (80% vs. 55%; P = 0.05). This hypothetical model merits further testing in a larger population of patients with PMLCL.

Primary mediastinal B-cell lymphoma: update of its clinicopathologic features

The peculiar clinical, histomorphological and biological characteristics of PMBCL are reviewed. Special emphasis is given to the frequent aggressive clinical behaviour of this lymphoma in which conventional prognostic factors seem inadequate to identify high risk cases. The need for new clinical and/or biological prognostic markers is stressed.

Endocrine characterization of primary mediastinal lymphoma

Because of the characteristic presentation of primary mediastinal large cell lymphoma (PMLCL) in young females its known origin from thymic B-cells, there might be a role in lymphomagenesis for estrogen receptors as well as for known neuroendocrine thymic mediators. A retrospective review of all patients with diffuse large cell lymphoma seen at our institution from January 1985 to January 1994 revealed 75 consecutive cases with a diagnosis of PMLCL. Through retrieval from our pathologic archives and requests to outside pathologists, we recovered and analyzed 17 biopsy specimens for the presence of the following hormone receptors: estrogen, beta endorphin, prolactin, T3, growth hormone, and leutinizing hormone. None of the specimens stained for any of the reagents. The most plausible explanation is that PMLCL tissues are devoid of these hormonal receptors and thus these receptors do not seem to play a role in the pathogenesis of PMLCL.

Primary mediastinal large B-cell lymphoma. A clinicopathologic study of 141 cases compared with 916 nonmediastinal large B-cell lymphomas, a GELA ("Groupe d'Etude des Lymphomes de l'Adulte") study

Among non-Hodgkin's lymphomas, primary mediastinal large B-cell lymphoma (PMLCL) has been considered a separate entity that has specific clinical and histological aspects and a poor prognosis. In this study, we reexamined the clinicopathologic features and the response to current treatment of 141 PMLCL and compare them with 916 nonmediastinal large B-cell lymphomas (NMLCL) recorded in the same period and treated with similar combined chemotherapy. The clinical features of PMLCL at diagnosis were largely homogeneous and distinct from NMLCL, with a predilection for young women (59% with a mean age of 37 years versus 42% with a mean age of 54 years), bulky tumor (77% versus 7%, p < 10(4)), high serum lactic dehydrogenase (LDH) level 76% versus 51%, p < 10(4)), and frequent intrathoracic extension to adjacent organs such as pleura, pericardium, and lung. By contrast, extrathoracic or hematologic dissemination was uncommon (2% of bone marrow involvement versus 17%). All patients had diffuse large B-cell nonimmunoblastic, nonanaplastic lymphomas. Histological analysis of the 141 PMLCL evaluated two common patterns: the presence of large cells with clear cytoplasm (found in 38% of cases) and the presence of fibrosis (marked in 25% of cases). The presence of clear cells or intense fibrosis did not constitute prognostic indicators. Immunologic and molecular analysis assessed the profile of bcl-2 expression and the presence of Epstein-Barr virus (EBV) in PMLCL: 30% expressed a high level of bcl-2 protein; EBER RNAs were detected by in situ hybridization in only two of the 41 cases tested. Monotypic light chain restriction could be demonstrated in seven of the 41 PMLCL tested on fixed-section. Treated with polychemotherapy regimens without radiotherapy, 79% of PMLCL patients achieved a complete remission compared with 68% in the NMLCL patient group (p = 0.01). Overall, 3-year survival rates were estimated at 66 and 61%, respectively (p = 0.05), and disease-free survival rates were not significantly different (61 versus 64%). Stratified analysis on the International Prognostic Index (based on age, tumor stage, serum LDH level, and performance status) showed no difference in the overall and disease-free survivals between the two lymphoma groups. In conclusion, PMLCL can be combined with other diffuse large B-cell lymphomas on morphologic grounds; it is not associated with EBV. It responds favorably to treatment and should be managed like other high-grade lymphomas of equivalent histology. However, the uncommon clinical presentation makes it a distinct entity.

Primary Mediastinal B-cell lymphoma with sclerosis: clinical and therapeutic evaluation of 22 patients

In the last decade, there have been several reports on what is now recognized as a new clinical and pathological entity termed primarily mediastinal B-cell lymphoma (PMBCL) with sclerosis. This lymphoma presents unique clinical characteristics with an aggressive outcome and, at present, the best approach seems to be a combination of chemotherapy and radiotherapy. Between June 1989 and September 1994, twenty-two previously untreated patients with PMBCL with sclerosis were treated with a combination of third-generation chemotherapy regimen (MACOP-B or F-MACHOP) and mediastinal irradiation. All the patients presented with bulky mediastinal involvement; the radiologic clinical stage with evaluation of tumor size included computed tomography and Gallium-67-citrate SPECT. Twenty-one patients (95%) achieved a complete response and only one was resistant to treatment. Regarding 67Ga SPECT, 6 patients, including the nonresponder, showed persistent abnormal 67Ga uptake after chemotherapy; however after the mediastinal radiotherapy, all the patients except for the nonresponder were 67Ga-negative. The overall survival was 87%, with a median follow-up of 24 months from the time of diagnosis. Two of the patients who achieved complete response relapsed 7 and 10 months after completion of treatment, respectively. The relapse-free survival rate was 89% at 62 months (median 20 months). In patients presenting with bulky mediastinal PMBCL with sclerosis combined modality treatment using third-generation chemotherapy regimens and radiotherapy induces a good remission rate with greater than 80% chance of surviving disease-free, at 2 years. A longer follow-up before definitive conclusions are drawn is still warranted.

Mediastinal large B-cell lymphoma: clinical and immunohistological findings in 18 patients treated with different third-generation regimens

We report on the immunophenotype, clinical findings and response to aggressive chemotherapy of 18 patients with mediastinal large B-cell lymphoma (MLCL). Cases were collected from a series of 286 high-grade non-Hodgkin's lymphomas (HG-NHL) which, in the period September 1988 to August 1991, were enrolled in a prospective multicentre trial designed to compare the MACOP-B and F-MACHOP regimens. Immunostaining on frozen sections revealed a previously unrecognized phenotype, i.e. co-expression of B-cell (CD19, CD20, CD22, Ig-associated dimer) and activation-associated antigens (CD30 and CDw70) in about 60% of MLCL cases; in contrast, the activation-associated antigens CD25 and Ki-27 (unclustered) were consistently negative. This peculiar phenotype may reflect a derivation of the tumour from a subset of thymic activated B cells. Clinically, the patients (median age 31 years; F/M ratio 2.6) presented with bulky mediastinal mass (72%) associated with mediastinal syndrome in > 50% cases; disease was stage IIA in most cases. All 18 patients received aggressive chemotherapy (F-MACHOP 11; MACOP-B 7). Complete response (CR) was achieved in 57.1% of cases treated with MACOP-B. In contrast, the response of the 11 MLCL treated with F-MACHOP was poor (CR 18.2%) as compared to that of the 135 HG-NHL treated with the same regimen during the trial (CR 69.6%). This difference was still statistically significant after adjusting for negative prognostic factors (mediastinal mass > 10 cm plus increased LDH) and suggests that F-MACHOP might not be the most appropriate regimen for this kind of lymphoma.

Primary mediastinal large cell lymphoma

PURPOSE

Primary mediastinal large cell lymphoma PMLCL is a recently described entity which has provoked considerable interest lately. The unique immunophenotype of the malignant cell, as well as conflicting reports regarding its response to therapy, prompted us to review the current literature focusing on the pathological and clinical aspects of this disease.

DESIGN

We reviewed the current literature that contained details on the clinical presentation, pathological profile and clinical outcome.

RESULTS

Most reports agree that PMLCL typically affects a young female population and presents with symptoms related to compression of mediastinal structures. Pathologically, the malignant cells may arise from a distinctive thymic medullary B cell subpopulation which is characterized by the following phenotype: CD19+, CD21-, CD20+, CD22+. Alterations of c-myc and lack of expression of HLA class 1 antigens on the tumour cell surface have been described. Response to treatment and clinical outcome have varied from one series to another and is possibly explained by the small number of patients in most series and by the heterogeneity of therapy. In general, the outcome does not appear to be worse than that of other large cell lymphomas although, given the young age of these patients, it might be expected to be more favourable.

CONCLUSIONS

Primary mediastinal large cell lymphoma is a distinct clinico-pathological entity characterized by: (1) a predominance of young adults; (2) female predominance (female/male ratio of 2:1) in contrast to the other large cell lymphomas; (3) CD19+/CD21- immunophenotype; (4) absence of HLA-class 1 antigen expression; (5) possible involvement of c-myc; (6) frequent dissemination at relapse to unusual anatomic sites in a pattern reminiscent of Burkitt's lymphoma. The role of radiotherapy and the optimal treatment for this disorder are issues that remain unresolved.

Mediastinal large-cell lymphoma with sclerosis (MLCLS)

In a retrospective analysis encompassing a 14 year period (1978-92), 22 patients (age range 19-71, median 30 years) were identified as having mediastinal large-cell lymphoma with sclerosis on the basis of clinical and pathological features. At presentation, 15/22 had 'bulky' disease and 11/22 had evidence of superior vena caval obstruction. Thirteen patients had stage II disease (6,II; 7,IIE), nine presented with stage IV disease. Complete remission (CR) was achieved in only 4/22 patients with the initial adriamycin-containing regimen. 'Good partial remission' (no clinical evidence of disease, minimal abnormalities of uncertain significance on radiological investigation) was achieved in a further seven patients and 'poor partial remission' (a reduction in measurable disease > 50%) in four, giving an overall response rate of 15/22 (68%). One patient died within 48 h of arrival at the hospital; 16 of the 17 remaining patients in whom anything less than CR was achieved subsequently received additional, alternative treatment (one chemotherapy, six mediastinal radiotherapy, nine both treatment modalities) but in only 2/16 did this result in any further degree of response. With a median follow-up of 5 1/2 years, 10/22 patients remain well without progression between 6 months and 14 years (5/6 in whom CR was eventually achieved and 5/11 in whom only partial remission was ever documented). The seven patients in whom the initial treatment demonstrably failed have all died. These results suggest that a proportion of patients with this rare subtype of high-grade B-cell lymphoma may be cured by chemotherapy alone and that the presence of a residual mediastinal mass after treatment does not necessarily imply treatment failure. However, patients in whom the initial chemotherapy fails have a very grave prognosis.

Fine-needle aspiration cytology of primary large-cell lymphoma of the mediastinum: cytomorphologic findings with potential pitfalls in diagnosis

We report the fine-needle aspiration (FNA) cytomorphologic features of six cases of primary mediastinal large-cell lymphoma with sclerosis. The series consisted of three men and three women with a median age of 36 yr. All the patients presented with a large anterior or superior mediastinal mass with no evidence of peripheral lymphadenopathy or hepatosplenomegaly. Two of the cases showed typical findings of lymphoma, characterized by hypercellular specimens with numerous individually scattered markedly atypical lymphoid cells present, demonstrating nuclear irregularity with the presence of nucleoli and surrounding scant to slight amount of cytoplasm. Numerous lymphoglandular bodies were seen in the background. Both cases were correctly diagnosed as representing non-Hodgkin's large-cell lymphomas. Two other cases had slight cellularity with the presence of a few scattered atypical lymphoid cells. Although a definite diagnosis was not rendered in either case, the possibility of malignant lymphoma was considered. Two other cases consisted predominantly of microtissue fragments with some associated scattered individual atypical cells. Within the microtissue fragments, the cells were distorted with a tendency to elongate and spindle in a prominent fibrous matrix. Our experience demonstrates that FNA cytology of primary mediastinal diffuse large cell lymphoma with sclerosis can be challenging, with a potential for a false-negative diagnosis due to limited cellularity secondary to the sclerosis or a misdiagnosis as a spindle cell neoplasm due to distortion of these cells by the fibrous matrix. To the best of our knowledge, we believe this is the first FNA series of primary mediastinal diffuse large cell lymphoma with sclerosis.