Diffuse histiocytic lymphoma with sclerosis: a clinicopathologic entity frequently causing superior venacaval obstruction

Mediastinal Lymphoproliferative Disorders

Lymphoproliferative disorders comprise 50% to 60% of all mediastinal malignancies in both children and adults. Primary mediastinal involvement is rare (∼5%), whereas secondary mediastinal involvement by systemic disease is more common (10% to 25%). Primary mediastinal disease is defined as involvement by a lymphoproliferative disorder of mediastinal lymph nodes, the thymus, and/or extranodal mediastinal organs without evidence of systemic disease at presentation. In this review, the clinical, radiologic, histopathologic, immunohistochemical, and genetic features of some of the most characteristic mediastinal lymphoproliferative disorders are presented. The entities discussed here include: classic Hodgkin lymphoma with emphasis on nodular sclerosis and mixed cellularity types, and non-Hodgkin lymphomas, including primary mediastinal (thymic) large B-cell lymphoma, mediastinal gray zone lymphoma, mediastinal diffuse large B-cell lymphoma, thymic marginal zone lymphoma, mediastinal plasmacytoma, T-lymphoblastic lymphoma, and anaplastic large cell lymphoma. Although not a malignant process, hyaline vascular Castleman disease is also discussed here as this disorder commonly involves the mediastinum. Despite multiple advances in hematopathology in recent decades, the day-to-day diagnosis of these lesions still requires a morphologic approach and a proper selection of immunohistochemical markers. For this reason, it is crucial for general pathologists to be familiar with these entities and their particular clinicoradiologic presentation.

Primary mediastinal large B cell lymphoma with coexisting aberrations of C-MYC and BCL-2: a case report and literature review

Primary mediastinal large B-cell lymphoma (PMLBCL) is an aggressive lymphoma characteristic with distinct clinical, morphologic, and immunophenotypic features. The rearrangements of C-MYC, BCL2 and/or BCL6 which are common in diffuse large B-cell lymphoma (DLBCL) are typically absent in PLMBCL. Here we proved a novel case of PMLBCL with concurrent rearrangements of C-MYC and BCL2. Histology showed typical pathomorphological features of PLMBCL. Fluorescent in situ hybridization (FISH) studies showed rearrangements of C-MYC and copy number variation (CNV) of BCL2 gene. It is not well known on the clinical significance of rearrangements of C-MYC and BCL2 genes in PMLBCL. The case gives evidence that cytogenetic testing is necessary for PMLBCLs to get precise clinical evaluation and appropriate treatment.

Primary Mediastinal Nodal and Extranodal Non-Hodgkin Lymphomas: Current Concepts, Historical Evolution, and Useful Diagnostic Approach: Part 1

Primary mediastinal non-Hodgkin lymphomas (PM-NHLs) represent ~5% of all NHLs and comprise lymphomas of B-cell and T-cell origin. PM-NHLs are defined as involvement of mediastinal lymph nodes, thymus, and/or mediastinal organs (heart, lung, pleura, pericardium) by NHL without evidence of systemic disease at presentation. The clinical scenario is variable and depends on the lymphoma subtype. The radiologic presentation is also variable ranging from a mediastinal mass with or without superior vena cava syndrome, a pleural or a cardiac mass associated with an effusion, or as an effusion only. The diagnosis of PM-NHLs can only be established by microscopic evaluation, and therefore, general pathologists should be aware of these tumors and familiar with their diagnostic approach. The most common anterior mediastinal NHLs (90% to 95%) are primary mediastinal large B-cell lymphoma and T lymphoblastic lymphoma. Thymic marginal zone lymphoma and mediastinal gray zone lymphoma are very rare. The remainder PM-NHLs involving middle or posterior mediastinum include diffuse large B-cell lymphoma (DLBCL) and rare cases of T-cell lymphoma, including anaplastic large cell lymphoma and breast implant-associated anaplastic large cell lymphoma extending to the anterior mediastinum. Primary pleural and cardiac NHLs are mostly DLBCLs. Other rare subtypes of PM-NHLs include DLBCL associated with chronic inflammation/pyothorax-associated lymphoma, fibrin-associated DLBCL (both EBV), and pleural and/or pericardial primary effusion lymphoma (HHV-8/EBV). We review the historical aspects, epidemiology, clinico-radiologic features, histopathology, immunohistochemistry, differential diagnosis, and relevant cytogenetic and molecular features of PM (thymic) LBCL, PM "nonthymic" DLBCL, BCL, unclassifiable, with features intermediate between DLBCL and classic Hodgkin lymphoma (mediastinal gray zone lymphoma), DLBCL associated with chronic inflammation (pyothorax-associated lymphoma), fibrin-associated DLBCL, and primary effusion lymphoma. This review represents the first part of 2 manuscripts covering PM-NHLs.

The role of pembrolizumab in relapsed/refractory primary mediastinal large B-cell lymphoma

Primary mediastinal large B-cell lymphoma (PMBCL) is a subtype of diffuse large B-cell lymphoma (DLBCL). PMBCL comprises approximately 10% of DLBCLs, thus making it a rare variant of DLBCL. Cure rates for PMBCL with upfront regimens like DA-REPOCH exceed 90%. However, if there is a poor response to this first-line therapy, relapsed/refractory PMBCL (rrPMBCL) has limited treatment options. The historic trend is to treat rrPMBCL with salvage regimens commonly used for DLBCL followed by high-dose therapy and autologous stem cell transplant (HDT-ASCT); however, response rates to salvage therapy remain low and few patients are able to proceed to transplant. An interesting feature of PMBCL is that even though it is classified as a subtype of DLBCL, PMBCL actually shares many clinical, pathologic, and genetic features with classical Hodgkin lymphoma (cHL). For example, both frequently express program death ligand 1 and 2 (PD-L1/2), which is not seen in other mature B-cell lymphomas. The expression of PD-L1/2 in PMBCL makes PDL1 inhibitors, such as pembrolizumab, an attractive therapeutic target. Pembrolizumab is an effective and well-tolerated therapy now approved for a number of cancer types from advanced melanoma to relapsed/refractory cHL. There are now multi-institutional trials underway assessing the role of pembrolizumab in the treatment of rrPMBCL.

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 large B-cell lymphoma

The management of primary mediastinal large B-cell lymphoma (PMBCL) requires a balance between optimizing chances of cure and reducing risk of long-term toxicities. The combination of rituximab to cyclophosphamide, doxorubicin, vincristine and prednisone (RCHOP) followed by mediastinal radiation results in a plateau in progression-free survival after first few years of follow-up. In rituximab era, a negative positron emission tomography (PET) scan performed after the completion of immunochemotherapy has a high predictive value for durable remission. Consequently, end-of-therapy PET may be utilizable to avoid radiation without compromising survival. Additionally, intensified chemotherapy alone has shown excellent survival. PMBCL is frequently associated with amplification of programmed death ligand (PDL) 1/2 and constitutive activation of JAK-STAT and NFKB pathways; these may serve as promising therapeutic targets. Clinical trials that integrate novel therapies into upfront immunochemotherapy and utilize end-of-therapy PET scan to guide mediastinal radiation have potential to further enhance survival and prevent long-term toxicities.

Primary mediastinal B-cell lymphoma in the pediatric patient: Can a rational approach to therapy be based on adult studies?

The literature on adult and pediatric primary mediastinal B-cell lymphoma (PMBCL) was reviewed and compared. Biologically, adult PMBCL has more similarities to Hodgkin Lymphoma (HL) than diffuse large B-cell lymphoma (DLBCL). Pediatric studies suggest that the biology is similar to that in adults. Median age of children is 14.3 years and the overall survival (OS) is reported as 78.6% and event-free survival (EFS) as 67.4%. Adverse prognostic factors included LDH >500 and mass size over 10 cm, with a trend towards better survival in younger patients. Studies in adults show better survival with intensified chemotherapy and the addition of rituximab. Data on the use of radiation therapy show improved CR rates and survival with addition of involved field radiation therapy (IFRT). Positron emission tomography (PET) with computerized tomography (CT) imaging response-assessment after two courses and at therapy-end may allow for the rational use of IFRT in pediatric/adolescent patients who are more susceptible to development of adverse late effects.

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 B-cell lymphoma: detection of BCL2 gene rearrangements by PCR analysis and FISH

Primary mediastinal large B-cell lymphoma (PMBCL) has a characteristic clinical presentation, morphology, and immunophenotype, representing a clinically favorable subgroup of diffuse large B-cell lymphoma (DLBCL). By gene expression profiling (GEP), PMBCL shares features with classical Hodgkin lymphoma (cHL). Of further interest, BCL6 gene mutations and BCL6 and/or MUM1 expression in a number of PMBCLs have supported an activated B-cell (ABC) origin. Several studies, including GEP, have failed to detect BCL2 gene rearrangements (GRs) in PMBCL. An index case of t(14; 18)+ PMBCL prompted our study of the incidence of BCL2 GRs in PMBCL by polymerase chain reaction (PCR)/fluorescence in situ hybridization (FISH) analyses and its possible clinical impact. Twenty-five retrospectively identified, well-defined PMBCLs (five with cytogenetics) from three institutions were analyzed for a BCL2 GR by PCR/FISH analyses. The formalin-fixed, paraffin-embedded tissue blocks of 24 available cases were also analyzed by BCL2 immunohistochemistry (IHC). Of the five with cytogenetics, two had a t(14; 18) (q32; q21). Of the 25 analyzed by PCR, 2 had no amplifiable DNA (aDNA), including 1 t(14; 18)+ case. Of those with aDNA, two showed a BCL2 GR; by FISH analysis, three demonstrated a BCL2 GR. BCL2 protein expression by IHC analysis was variably detected in 21 out of 24 (strongly, uniformly expressed: 6, including all with a t(14; 18) or a BCL2 gene rearrangement; moderately weakly expressed in a subset of the malignant cells: 15). Available clinical follow-up of this BCL2+ subset showed a similar course to the other PMBCL cases. Our results imply that a subset of PMBCL [(4 out of 24 analyzed) in our series] may be of GC origin. A larger study is necessary to determine any clinical significance.

Primary mediastinal B-cell lymphoma

Primary mediastinal B-cell lymphoma (PMBCL) is a sub-type of the heterogeneous diffuse large B-cell lymphoma category, and comprises approximately 5% of all non-Hodgkin's lymphomas (NHL). It was first recognized as a distinct clinico-pathologic entity 20 years ago, and recent work has further characterized specific molecular features. Gene expression profiling has suggested a partial overlap with nodular sclerosing Hodgkin lymphoma (HL), with which it shares some clinical features. The optimal management remains a matter of debate. There is uncertainty as to whether weekly alternating chemotherapy regimens may be more effective than CHOP, whether consolidation radiotherapy (RT) to the mediastinum is always required, whether PET scanning can be used to determine this, and whether the use of rituximab as part of initial therapy will change the answers to these questions. The International Extranodal Lymphoma Study Group (IELSG) 26 clinicopathologic study of PMBCL, which has recently opened, represents a first attempt to gather data prospectively on some of these issues.

Primary mediastinal large B-cell lymphoma with sclerosis in pediatric and adolescent patients: treatment and results from three therapeutic studies of the Berlin-Frankfurt-Münster Group

PURPOSE

Primary mediastinal large B-cell lymphoma with sclerosis (PMLBL) is a rare entity of non-Hodgkin's lymphoma (NHL) arising from thymic mature B cells. Optimal treatment strategies remain to be established, especially in pediatric patients.

PATIENTS AND METHODS

This study analyzes clinical characteristics and treatment outcome of 30 pediatric patients with PMLBL, diagnosed in multicenter therapy NHL-Berlin-Frankfurt-Münster Group (BFM) trials. Treatment was stratified by stage and serum lactate dehydrogenase (LDH) and consisted of four to six 5-day courses of chemotherapy using steroids, oxazaphosphorine alkylating agents, methotrexate, cytarabine, etoposide, and doxorubicin. Radiation was not part of the protocol.

RESULTS

From April 1986 to August 1999, 1,650 patients with newly diagnosed NHL were enrolled in the NHL-BFM trials; 30 patients (1.8%) had PMLBL. Median age was 14.3 years (range, 1.4 to 16.7 years); 15 patients were male and 15 patients were female. With a median observation time of 5 years (range, 1 to 12 years), probability of event-free survival (pEFS) at 5 years was 0.70 (SE, 0.08). Two patients erroneously diagnosed as T-cell NHL received non-B-cell therapy and died from progress of disease. Events in 28 patients receiving B-cell therapy included early progress during therapy (n = 1) and relapse (n = 6). Residual mediastinal masses were present in 23 patients after two courses of therapy and in 15 patients after the end of therapy. LDH > or = 500 U/L was associated with increased risk of failure in multivariate analysis.

CONCLUSION

PMLBL mainly is found in adolescents. Dose-intense chemotherapy including high-dose methotrexate yields a pEFS at 5 years of 0.70 (SE, 0.08). LDH is of prognostic value in pediatric patients with PMLBL.

Autologous and allogeneic transplantation for aggressive NHL

BACKGROUND

Intermediate- and high-grade NHL are generally chemosensitive diseases with high initial response rates to combination chemotherapy. Dose intensification via autologous and allogeneic transplantation provides viable treatment options in specific clinical settings. Currently, autologous transplantation is the standard of care for relapsed but chemosensitive aggressive B-cell NHL. However, tools such as the International Prognostic Index allow risk-adapted analyses, and show that the magnitude of benefit from autologous transplantation differs in lymphoma subsets.

METHODS

Low-risk patients appear to do well regardless of salvage approaches, whereas high-risk patients have suboptimal outcomes with autologous transplantation. In high-risk patients, high-dose chemotherapy with autologous stem-cell transplantation has been examined as part of initial therapy, with long-term data promising but still evolving.

DISCUSSION

A significant concern with autologous transplantation in aggressive and high-grade NHL is the risk of graft contamination with tumor cells. Several investigators have demonstrated the presence of malignant cells in both BM and PBSC, although the clonagenic potential of such cells is unclear. Allogeneic stem-cell transplantation has several potential advantages over autologous transplantation for NHL,including procurement of an uncontaminated stem-cell graft, GvL effects, and the elimination of hematopoietic stem-cell damage and consequent secondary leukemia.

RESULTS

The ideal application of allogeneic transplantation in aggressive and high-grade lymphomas is still unclear; but the lower relapse rates demonstrated in several comparisons of the two approaches make this an exciting area to pursue. Finally, non-myeloablative stem-cell transplantation may broaden the use of allogeneic transplantation by lowering regimen-related mortality while capitalizing on GvL.

Diffuse large B-cell lymphoma with primary retroperitoneal presentation: clinico-pathologic study of nine cases

Diffuse large B-cell lymphoma primarily presenting in the retroperitoneum (PRLBCL) has been the object of occasional reports, all based on dated techniques.

MATERIALS AND METHODS

Nine PRLBCLs--with clinical information and paraffin blocks available--were reviewed on morphologic, immunohistochemical and molecular grounds.

RESULTS

At microscopic examination, the cases were characterized by a diffuse proliferation of large cells (CD20+, CD79a+, CD3-), displaying a wide rim of cytoplasm (clear in seven instances and acidophilic in two), associated with sclerosis and frequent compartmentalization. Phenotypic and molecular analyses showed that: a) three cases were bcl-2+, bcl-6+, HLA-DR+, and CD10+ (1/3), with associated follicular dendritic cell (FDC) component and bcl-2 gene rearrangements; b) four cases were bcl-2, bcl-6, HLA-DR, CD10, FDC, and bcl-2 gene rearrangement negative; c) two cases had border-line characteristics (bcl-2+, bcl-6+, FDC+, HLA-DR-, CD10-, and bcl-2 gene rearrangement-). The first subgroup was thought to be of follicular derivation, as was the third due to bcl-6 and FDC stains. Of the corresponding five patients, three are in complete remission and two died of disease within 12 months. No obvious, normal counterpart was detected in the remaining four tumors: the corresponding patients died of disease in 3-23 months. The problem of similarities between PRLBCL and primary mediastinal LBCL is discussed.

CONCLUSIONS

Although the present series is small, our findings suggest that PRLBCL may represent a more heterogeneous group of tumors than previously thought, which merits further phenotypic and molecular studies to broaden the understanding of its histogenesis and behavior.

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.

Large-cell lymphoma arising in the mediastinum in children and adolescents is associated with an excellent outcome: a Children's Cancer Group report

PURPOSE

Large-cell lymphoma (LCL) arising in the mediastinum (LCL-M) is a heterogeneous group of non-Hodgkin's lymphoma (NHL) that includes B-cell lymphomas as well as T-cell lymphomas, including anaplastic LCL. LCL-M is well recognized in young adults but is less well characterized and infrequent in children and adolescents.

METHODS

A retrospective review of Children's Cancer Group therapeutic studies for nonlymphoblastic lymphomas (CCG-551, CCG-503, CCG-552, and CCG-5911) identified 20 patients with LCL-M, representing 7.2% of all LCLs classified by central pathology review.

RESULTS

The patients ranged in age from 4 to 19 years (median, 12.5 years; mean, 12 years); 55% of the patients were male. Although a variety of chemotherapy regimens were used, response was excellent, with all 20 patients (100%) achieving a complete response. Four patients (20%) experienced relapse locally or in distant sites including brain and kidney. One patient died of sepsis during therapy. For the 20 patients with LCL-M, the product-limit estimated 5-year event-free survival (EFS) and 5-year overall survival (OS) rates are 75% +/- 10% and 85% +/- 8%, respectively. For disseminated LCLs (192 cases), the EFS and OS rates were 50% +/- 4% and 63% +/- 4%, respectively, which differ significantly from the those of the LCL-M cases (EFS, P =.025; OS, P =.034). The 5-year EFS and OS rates for patients with localized LCL (67 cases) were 92 +/- 3% and 97 +/- 2%, respectively.

CONCLUSION

LCL-M is a heterogeneous group of NHLs that makes up approximately 7.2% of LCL in children and adolescents. Response to therapy and OS in this young age group seems excellent and superior to that of disseminated LCLs but inferior to that of other localized LCL. Future studies of LCL-M will evaluate short intense chemotherapy administered without radiation therapy.

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.

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.

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.

Primary Diffuse Large B-Cell Lymphoma of the Mediastinum: Outcome Following High-Dose Chemotherapy and Autologous Hematopoietic Cell Transplantation

We performed a retrospective analysis of 35 patients with primary diffuse large B-cell lymphoma of the mediastinum treated with high-dose cyclophosphamide, carmustine, and etoposide (CBV) plus autologous hematopoietic cell transplantation to determine outcome and prognostic features for progression-free survival (PFS). Thirty-five patients with primary diffuse large B-cell lymphoma of the mediastinum in first response (complete remission [CR] or partial remission [PR]) with poor prognostic features, with primarily refractory disease, or with relapsed disease following conventional chemotherapy, were treated with CBV and autologous hematopoietic cell transplantation. PFS and overall survival were assessed by the Kaplan-Meier method. Patient characteristics before transplantation were examined by univariate analysis using the log-rank test and by Cox's proportional hazards regression analysis to determine predictors of PFS. Estimated 5-year PFS varied significantly with patient disease status at transplantation. Patients transplanted in first response had an estimated 5-year PFS rate of 83%, compared with 58% and 27% for primarily refractory and relapsed patients, respectively (P = .02). The strongest predictor of PFS was chemotherapy responsiveness immediately before transplantation. Patients with chemotherapy-responsive disease had a significantly greater PFS rate than patients with chemotherapy-nonresponsive disease (risk ratio, 3.60; 95% confidence interval [CI], 1.14 to 11.4). No other factors were found to be significant on univariate or multivariate analysis. Patients with primary diffuse large B-cell lymphoma of the mediastinum can achieve prolonged PFS following high-dose chemotherapy and autologous hematopoietic cell transplantation. Outcomes are strongly correlated with disease status (first response v refractoryv relapsed) at transplantation and chemotherapy responsiveness immediately before transplantation.

Primary Diffuse Large B-Cell Lymphoma of the Mediastinum: Outcome Following High-Dose Chemotherapy and Autologous Hematopoietic Cell Transplantation

We performed a retrospective analysis of 35 patients with primary diffuse large B-cell lymphoma of the mediastinum treated with high-dose cyclophosphamide, carmustine, and etoposide (CBV) plus autologous hematopoietic cell transplantation to determine outcome and prognostic features for progression-free survival (PFS). Thirty-five patients with primary diffuse large B-cell lymphoma of the mediastinum in first response (complete remission [CR] or partial remission [PR]) with poor prognostic features, with primarily refractory disease, or with relapsed disease following conventional chemotherapy, were treated with CBV and autologous hematopoietic cell transplantation. PFS and overall survival were assessed by the Kaplan-Meier method. Patient characteristics before transplantation were examined by univariate analysis using the log-rank test and by Cox's proportional hazards regression analysis to determine predictors of PFS. Estimated 5-year PFS varied significantly with patient disease status at transplantation. Patients transplanted in first response had an estimated 5-year PFS rate of 83%, compared with 58% and 27% for primarily refractory and relapsed patients, respectively (P = .02). The strongest predictor of PFS was chemotherapy responsiveness immediately before transplantation. Patients with chemotherapy-responsive disease had a significantly greater PFS rate than patients with chemotherapy-nonresponsive disease (risk ratio, 3.60; 95% confidence interval [CI], 1.14 to 11.4). No other factors were found to be significant on univariate or multivariate analysis. Patients with primary diffuse large B-cell lymphoma of the mediastinum can achieve prolonged PFS following high-dose chemotherapy and autologous hematopoietic cell transplantation. Outcomes are strongly correlated with disease status (first response v refractoryv relapsed) at transplantation and chemotherapy responsiveness immediately before transplantation.

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.

Inflammatory pseudotumor of lymph nodes: a study of 25 cases with emphasis on morphological heterogeneity

The clinicopathological and immunohistochemical findings in 25 cases of inflammatory pseudotumor of lymph nodes (IPT) are presented. The patients were 13 women and 12 men between 8 and 81 years of age. Clinically, symptoms of prior infection, fatigue, abdominal pain, weight loss, fever of unknown origin, pelvic inflammatory disease, or nausea and night sweats were obtained in 15 patients, whereas six patients presented with asymptomatic lymphadenopathy. In four additional patients, no clinical information was obtained. The involved nodes included cervical, supraclavicular, inguinal, mesenteric, and mediastinal lymph nodes. In two cases, there was synchronous involvement of separate lymph node groups (inguinal and cervical in one case and cervical and mediastinal in another case), whereas in a third patient there was synchronous involvement of the spleen and a paraaortic lymph node. Histologically, the lesions were characterized by a fibrosing/inflammatory process that showed marked heterogeneity and striking variation from case to case. Based on their histological features, the lesions could be classified into three different groups: Stage I was characterized by the appearance of single or multiple small foci containing a spindle cell proliferation admixed with a prominent inflammatory background, with complete preservation of the remainder of the nodal architecture; stage II was characterized by more diffuse involvement of the lymph node with a marked inflammatory response admixed with a prominent myofibroblastic proliferation leading to subtotal effacement of the nodal architecture, often with extension of the process beyond the capsule into perinodal fat; and stage III was characterized by almost complete replacement of the lymph node by diffuse sclerosis with scant residual inflammatory elements and total loss of the normal nodal architecture. Immunohistochemical studies in 20 cases showed a striking number of vimentin- and actin-positive myofibroblastic cells with moderate increase in CD20/CD45+ small lymphocytes and polyclonal plasma cells in the stage I lesions, the emergence of numerous CD68+ histiocytes admixed with lymphocytes, plasma cells, and abundant fibromyofibroblastic cells in the stage II lesions, and only few remaining scattered CD68+ histiocytes and fibroblasts in the stage III lesions. Our findings suggest that inflammatory pseudotumor of lymph node represents an evolving, dynamic process that may adopt different morphological appearances depending on its stage of evolution. Recognition of the various stages of this process may be of importance for differential diagnosis with other fibrosing/inflammatory conditions of lymph nodes.

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.

Pleomorphic large cell lymphomas of the mediastinum

Nine cases of primary non-lymphoblastic, non-Hodgkin's large cell lymphomas of the mediastinum characterized by a highly pleomorphic histologic appearance are described. The patients, four women and five men, were aged 30 to 65 years. All patients presented with symptoms referable to their tumors, including cough, chest pain, dyspnea, pleural effusion, and superior vena cava syndrome. Clinical and pathologic staging in all patients showed that the bulk of the tumor was confined to the chest cavity at the time of initial diagnosis, with local infiltration into the neck, lung hilum, and surrounding mediastinal structures. Three different histological growth patterns were observed: one composed of a diffuse proliferation of pleomorphic, highly atypical cells with bizarre nuclear features that closely resembled a high grade sarcoma; another one composed of sheets of large, epithelial-appearing atypical cells suggestive of anaplastic carcinoma; and another pattern characterized by a pleomorphic proliferation of large lymphoid cells admixed with numerous scattered Reed-Sternberg-like cells reminiscent of the lymphocyte-depleted variant of Hodgkin's disease. Immunohistochemical studies on paraffin-embedded tissue sections in all cases showed positive staining of the tumor cells with CD20 and CD45 antibodies and negative staining with a large panel of markers, including broad-spectrum keratin, CAM 5.2, carcinoembryonic antigen, epithelial membrane antigen, vimentin, actin, desmin, HMB 45, S-100 protein, CD3, CD15, CD30, and CD45RO. Because of their location restricted to the anterior mediastinum, frequent lack of recognizable lymph node architecture, and bizarre cytologic features, the present group of lesions posed difficulties for diagnosis, their correct identification was achieved through the application of a panel of immunohistochemical markers. An awareness of these unusual histologic appearances of primary large cell lymphoma in the mediastinum and inclusion of a broad panel of lymphoid markers are therefore recommended for the evaluation of pleomorphic, undifferentiated malignant neoplasms of this anatomic region.

Primary mediastinal large cell lymphoma in children: a report from the Childrens Cancer Group

Malignant lymphomas arising in the mediastinum account for approximately 60% of all mediastinal tumors in children; two-thirds are non-Hodgkin's lymphomas and one-third represent Hodgkin's disease. In contrast to adults, in children mediastinal non-Hodgkin's lymphomas are usually synonymous with lymphoblastic lymphoma, and nonlymphoblastic lymphomas are rare. We describe nine children with primary mediastinal large cell lymphoma who were treated with the Children's Cancer Group protocol CCG-503, a randomized phase III protocol for disseminated nonlymphoblastic lymphoma. Histologic subclassification revealed three immunoblastic lymphomas, three multilobated large cell lymphomas, one with clear cell features, and two large noncleaved cell lymphomas. Sclerosis, of variable degrees, was seen in all tumors. Immunophenotyping revealed all tumors to be of B cell lineage. Thymic epithelial cells could be demonstrated, utilizing antibody to keratin, in two of nine patients, suggesting that some of the tumors are of thymic origin. None of the patients had central nervous system or bone marrow involvement. It appears that primary mediastinal nonlymphoblastic lymphomas in children, although much less common, are similar to those seen in adults. These tumors must be differentiated from lymphoblastic lymphoma and Hodgkin's disease, as the therapeutic approach may depend on histologic subtype. Primary mediastinal large cell lymphoma in children appears curable with aggressive treatment in the majority of patients.

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.

Childhood B cell lymphomas arising in the mediastinum

AIMS

To report the clinical features and pathology of four childhood cases of primary mediastinal non-Hodgkin's lymphoma of non-lymphoblastic pathology.

METHODS

Biopsy material was fixed in formol-saline and routinely processed and stained. Immunohistochemical staining was performed on paraffin wax embedded sections using the alkaline phosphatase anti-alkaline phosphatase method.

RESULTS

The four patients presented with a large mediastinal mass and symptoms consistent with superior vena cava syndrome secondary to lymphoma. None of the patients had any clinically important disease outside the mediastinum. The four tumours had a histological appearance similar to diffuse large cell non-Hodgkin's lymphoma with sclerosis. Immunohistochemical staining showed that these tumours were of B cell origin. One patient died from infection during treatment and two patients died with progressive disease. The remaining patient remained well 43 months off all treatment.

CONCLUSIONS

These four cases further illustrate the heterogeneity of paediatric large cell lymphomas. Clinically, they seem to be equivalent to the B cell lymphoma of the mediastinum, sclerosing type, that is seen in young (predominantly female) adults. The clinical and biological features of this type of tumour in childhood are largely unknown. Using standard treatment protocols, this tumour seems to have a poor prognosis and its optimal treatment therefore requires further clarification.

Clinicopathologic study of primary mediastinal non-lymphoblastic non-Hodgkin's lymphomas among the Japanese

We studied the morphologic, immunologic and clinical features of 14 cases of primary non-lymphoblastic non-Hodgkin's lymphomas of the mediastinum. The patients ranged in age from 3 to 76 years, with a median age of 28 years. According to the Ann Arbor classification, 71% of our cases were in an early stage. Three cases were in Stage I, eight in Stage II, one in Stage III and two in Stage IV (one with multiple hepatic lesions and another with bone marrow involvement). The patients were heterogeneous in terms of the disease and were therefore histologically classified into three categories: diffuse large B cell lymphoma with sclerosis (DLS; n = 8); large cell anaplastic lymphoma (LC-Ana; n = 5); and low grade B cell lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma; n = 1). DLS was the most common group and was characterized as CD5-, CD10-, CD19+, CD20+, CD21- and CD22+. Imprint smears showed azurophilic granules in the cytoplasm of the tumor cells of three of four DLS cases. All of the six cases examined were negative when tested for Epstein-Barr virus (EBV) sequences after hybridization with the EBV internal repeat probe. DLS and MALT lymphoma cases were of a B-lineage lymphoma of the thymus, while most of the LC-Ana cases were of a T-lineage lymphoma. Patients with non-lymphoblastic non-Hodgkin's lymphomas had a relatively favorable prognosis compared with lymphoblastic lymphoma (P < 0.01 by the generalized Wilcoxon test). There was no significant difference in the survival between non-lymphoblastic non-Hodgkin's lymphoma and Hodgkin's disease (P > 0.05 by the generalized Wilcoxon test).

Large cell lymphoma of the mediastinum with marked tropism for germinal centers

The cases are presented of three patients with large cell malignant lymphoma of the mediastinum with a distinctive growth pattern characterized by marked tropism of tumor cells for germinal centers. The patients' ages ranged from 35 to 70 years; one was a woman, and two were men. Histologically, the lesions were characterized by a proliferation of large atypical cells arranged in clusters that encroached on mantle zones and invaded germinal centers. Immunohistochemical studies showed positive staining of the tumor cells for leukocyte common antigen, L-26 (pan-B-cell antigen), and lambda light chain restriction and negative staining with Leu-M1, UCHL-1 (pan-T-cell antigen), Ber-H2 (Ki-1 antigen), S-100 protein, HMB-45, low-molecular weight keratins, epithelial membrane antigen, carcinoembryonic antigen, and placental alkaline phosphatase. Electron microscopy done on one specimen showed cells with abundant cytoplasm, some of them containing surface microvilli, scant organelles, and scattered polyribosomes consistent with lymphoid cells. Because of their unusual growth pattern and morphology, these tumors can be mistaken for primary or metastatic carcinomas, germ cell tumors (particularly seminomas), and metastatic malignant melanomas. It is proposed that the "germinotropic" features observed in these lesions are the result of active colonization of germinal centers by the tumor cells. The possible pathogenetic implications of this phenomenon are discussed.

A study of 15 cases of primary mediastinal lymphoma of B-cell type

Fifteen cases of pure supradiapragmatic lymphoma with initial prominent antero-superior mediastinal involvement displaying a B-cell pattern of reactivity were studied. These cases occurred in six men and nine women with a median age of 33 years at diagnosis (range, 23 to 75 years). Supradiapragmatic peripheral lymphadenopathies were present in three cases, and intrathoracic extension to the lung, pericardium, or pleura was possible. In five cases a thymic origin was obvious. All cases exhibited a B-cell pattern of differentiation, with a great variety of histopathologic aspects associated with a high frequency of fibrosis and/or necrosis. Hodgkin's disease was initially misdiagnosed in four cases. The evolution was purely local, with extrathoracic extension in five cases, at the ultimate phase of the disease. The prognosis appeared to be poor with only five patients still alive at a median survival time of 16 months. A complete chemoresistance and radio-resistance was observed in seven cases; only two complete remissions were achieved with aggressive chemotherapy. Prolonged remission could be achieved after surgical reduction of the mass. Primary B-cell mediastinal lymphoma appears to be a distinct clinical entity with local evolution and resistance to therapy. A new therapeutic regimen, which could include surgery in some cases, should be found for this disease.

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

In a series of 193 patients with advanced stage diffuse large-cell lymphoma (DLCL) treated with MACOP-B, 18 (11%) were defined as having a stage II large B-cell lymphoma with sclerosis of the mediastinum. This type of lymphoma has been reported to have a highly aggressive behaviour and special histological and clinical features. In our series young women were more commonly affected and the most striking clinical feature was the presence of a bulky mediastinal mass in 81%. A comparison was made between stage II patients with DLCL with and without sclerosis. The group of patients with sclerosis had prognostic parameters significantly worse than those of the patients without sclerosis, namely, elevated LDH level and bulky disease. The complete remission rates (89% vs 76%) were similar in the two groups and, with a median follow-up of 23 months, survival and disease-free survival rates were also superimposable. MACOP-B chemotherapy has been proven effective in this subgroup of lymphoma patients with sclerosis that had thus far been reported to have a poor prognosis.

Lymphomas of the mediastinum

The purpose of this clinicopathologic overview is to describe the types of lymphomas that present in the mediastinum. A comparison of the frequency of the different subtypes of lymphoma that are found in children and adults is provided. In general, immunohistochemistry and immunophenotyping studies are essential to the laboratory workup of neoplasms presenting in the mediastinum. An assessment of proliferative index in lymphoma is most helpful to determine tumor aggressiveness and patient prognosis. Electron microscopy is most helpful in the differential diagnosis of mediastinal neoplasms, where lymphomas may be distinguished from nonlymphomatous neoplasms using key ultrastructural features. The role of electron microscopy in the subclassification of lymphomas is mostly academic, with a few exceptions. The varied ultrastructural appearance of Hodgkin's cells and of different subtypes of non-Hodgkin's lymphoma is illustrated, using cases from our patient files. An ultrastructural study of lacunar cells in Hodgkin's disease provides evidence that the formation of lacunae may have a structural and/or physiologic basis. Mummified cells showing some of the features of a physiologic form of cell death, called apoptosis, are also described.

Primary anterior mediastinal B-cell lymphoma. A clinicopathologic and immunohistochemical study of 16 cases

Sixteen cases of primary anterior mediastinal B-cell lymphoma were characterized by morphologic, immunophenotypic, and clinical profiles. Twelve were men and four were women. The median age was 42 years. Virtually all tumors were of large cell type. Three main morphologic categories were identified, with one rare exception. In some tumors, the cells were compatible with centrocytes and centroblasts (four). Others had cells readily identifiable as centroblasts (six). Both these groups had a variable proportion of cells with multilobed nuclei. A third group was composed mainly of unclassifiable cells with multilobed nuclei (five). All had discernible sclerosis of varying intensity. A wider range of morphologic features and different sex distribution was noticed in comparison with previously reported clear cell features and younger women. The dominant phenotype of these B-cell lymphomas was CD19+, CD22+, CD37+, CD21-, CD30-, CD10-, CD5-, and Ig-negative. The finding of CD21-, Ig-negative phenotype, as observed by the authors and others, overlaps with some high-grade lymphomas of follicular center cell origin but is thought to bear similarity to a noncirculating population of thymic medullary B-cells. The tumors attained large size without peripheral dissemination and responded to chemotherapy as well as radiotherapy.

Imprint cytology of non-Hodgkin's lymphomas based on a study of 212 immunologically characterized cases: correlation of touch imprints with tissue sections

The classification of non-Hodgkin's lymphomas (NHLs) has been traditionally based on analysis of histologic sections and has been supplemented more recently by immunologic marker studies. It was the purpose of the present study to illustrate, side-by-side, sections and Romanowsky-stained imprints from the same surgical specimen from practically all categories of immunophenotyped NHLs, including rare and atypical variants that were difficult to classify from the histologic sections alone. Our results indicate that imprint cytology may reveal nuclear and cytoplasmic details not discernible in even the best tissue sections and that it may be selectively helpful in contributing to the classification of NHLs. Our results also show that the relative value of imprint cytology in the classification of malignant lymphomas varies greatly among categories. Specifically, we have found that imprints assist in three ways: the recognition of plasmacytoid features in small cell lymphocytic lymphomas, the recognition of plasmacytoid immunoblastic lymphoma, and the differentiation between NHLs which may be difficult to distinguish histologically. These include (1) small lymphocytic lymphoma versus lymphocytic lymphoma of intermediate differentiation, (2) true histiocytic malignancies versus large cell malignant lymphomas with abundant cytoplasm and/or phagocytosis, (3) anaplastic myeloma versus plasmacytoid immunoblastic lymphoma, (4) large noncleaved versus plasmacytoid immunoblastic lymphoma, (5) lymphoblastic lymphoma versus diffuse small cleaved cell lymphoma, and (6) lymphoblastic lymphoma versus small noncleaved cell lymphoma. Lymph node imprints are easy to prepare and readily interpretable by those experienced in the study of abnormal blood and bone marrow films. Their value as an ancillary methodology aimed at optimal accuracy in the classification of NHLs should be recognized.

Residual masses on follow-up computed tomography in patients with mediastinal non-Hodgkin's lymphoma

During the last 4 years we have treated four patients with extensive mediastinal non-Hodgkin's lymphoma (NHL). None had extrathoracic disease and they were clinically stage I-II. All received intensive combination chemotherapy and radiotherapy resulting in good response. Nevertheless, when treatment was completed, computed tomography (CT) showed a residual mediastinal mass in all four patients, who have remained alive and well for more than 19 to 45 months after completion of therapy and without any supplemental treatment. The residual masses gradually regressed or resolved on follow-up CT, suggesting that they did not contain malignant components.

Histological and immunohistological analysis of human lymphomas

Morphological and immunological characteristics of lymphoproliferative diseases are reviewed. In particular, a basic distinction is made between non-Hodgkin's lymphomas and Hodgkin's disease. As to the non-Hodgkin's lymphomas, emphasis is given to the problems of classification, technical approach, histogenesis, and prognosis. The authors adopt a version of the Kiel Classification modified to take account of new knowledge regarding T-cell lymphomas. The value of immunophenotyping in making an accurate distinction between the various categories is stressed; immunocytochemical detection of the growth fraction is also discussed and then proposed as a new prognostic tool. Finally, the criteria for differential diagnosis between non-Hodgkin's lymphomas, malignant histiocytosis, non-lymphoid large cell tumors, and atypical immune reactions are outlined.

Mediastinal large cell lymphoma. An uncommon subset of adult lymphoma curable with combined modality therapy

Thirty adults with large cell lymphoma predominantly localized to the mediastinum diagnosed at the Massachusetts General Hospital between 1976 and 1985 were identified. The median age of the 20 females and 10 males was 34 years. All but one presented with symptoms due to an enlarging mediastinal mass, which was localized in 22 patients (73%) and exceeded 10 cm in maximal diameter in 65%. Superior vena cava syndrome and large pleural and pericardial effusions were common. Employing CHOP chemotherapy (cyclophosphamide, doxorubicin, vincristine, prednisone) and consolidation radiation therapy in most cases, 80% achieved a complete remission and 59% survive failure-free at 5 years by actuarial calculation. The size of the mediastinal mass adversely affected failure-free survival (89% vs. 40%, P less than 0.05). No other pretreatment risk factor predicted outcome, but more intense chemotherapy was associated with improved survival (P = 0.035). Large cell mediastinal lymphoma is a locally invasive, often bulky malignancy with a predilection for young women; disease of low or moderate bulk is curable with full dose CHOP chemotherapy and consolidation radiation, but bulky disease requires more aggressive treatment.

Primary lymphoma of the head of the pancreas

Primary and isolated lymphoma of the head of pancreas with secondary involvement of the lungs and obstructive jaundice, in a 31-year-old postpartum woman, is described. The histological diagnosis was diffuse histiocytic lymphoma. Chemotherapeutic treatment resulted in complete remission of the tumor. During therapy a pseudocyst of the pancreas developed and a gastrocystostomy was performed. This is the second reported case of primary pancreatic lymphoma in the English medical literature.

Mediastinal large-cell lymphoma of B-type, with sclerosis: histopathological and immunohistochemical study of eight cases

Eight cases of mediastinal non-lymphoblastic large-cell lymphoma have been studied by histopathological and immunohistochemical methods. A common clinical, morphological and immunophenotypic pattern was identified. Six of eight cases proved to be of B-cell origin by the expression of B-associated antigens detected by specific monoclonal antibodies. Cells of large size with nuclei of varying morphology and a peculiar type of fine compartmentalizing fibrosis were observed in all specimens. Clinically the disease was characterized by the young age of the patients, primary mediastinal involvement, aggressive behaviour and spread to unusual sites (kidneys in four cases). This seems to be a hitherto unrecognized entity in the field of non-Hodgkin's lymphomas, often misdiagnosed because of location and a morphology uncommon for B-cell malignancies. Immunohistochemical analysis on frozen tissue sections appears to be mandatory for a correct diagnosis. Nevertheless, this type of lymphoma could be suspected also on the basis of its peculiar clinicopathological characteristics.