Large B-cell lymphoma rich in T-cells and simulating Hodgkin's disease

T-Cell-Rich B-Large-Cell Lymphoma Simulating Hodgkin's Disease: Report of Two Cases with Transformation to Pleomorphic B-Large-Cell Lymphoma

Malignant lymphomas resembling Hodgkin's disease in which the Hodgkin's-like cells express a B-cell phenotype pose a diagnostic and therapeutic dilemma. Recent studies have suggested these lymphomas are T-cell-rich B-large-cell lymphomas. In the present study we present two cases of malignant lymphomas meeting the histologic criteria for Hodgkin's disease, in which the Hodgkin's-like cells expressed a B-cell phenotype (CD20 positive, CD 15 negative, CD30 negative). In both cases therapy for Hodgkin's disease was unsuccessful, and the histology at relapse was that of a pleomorphic B-cell large-cell lymphoma. The findings support the view that malignant lymphomas resembling Hodgkin's disease, in which the Hodgkin's-like cells express a B-cell phenotype, are T-cell-rich B-large-cell lymphomas, and suggest a role for immunophenotyping of atypical cases of Hodgkin's disease.

Extra-nodal subcutaneous Hodgkin's-like lymphoma and subsequent regression in a cat

Hodgkin's-like lymphoma is a slow growing neoplasm, usually affecting the lymph nodes of the head and neck, which has been sporadically described in veterinary patients. This report describes the clinical and histopathological features in a 9-year-old male neutered Siamese cat that presented with a 6 week history of mid-dorsocranial swelling. Immunohistochemistry demonstrated positive staining for CD79a, paired box protein and B lymphocyte antigen-36, with variable, weak-to-moderate cytoplasmic staining for human leukocyte antigen-DR and CD18, and negative staining for antimacrophage antibody. The diagnosis based on incisional biopsy was Hodgkin's-like lymphoma; however, no evidence of neoplasia was found following wide surgical excision. This case report demonstrates two unreported items of note: the novel extranodal site of Hodgkin's-like lymphoma in a cat and tumour regression following initial biopsy. It is hypothesised that the surgical trauma of biopsying the lesion or the introduction of foreign material may have caused the regression of the neoplastic cells through induction of an anti-tumour immune or inflammatory response.

Matched-pair analysis comparing the outcomes of T cell/histiocyte-rich large B cell lymphoma and diffuse large B cell lymphoma in patients treated with rituximab-CHOP

BACKGROUND

T cell/histiocyte-rich large B cell lymphoma (THRLBCL) is a rare morphological variant of diffuse large B cell lymphoma (DLBCL), accounting for 1-3% of all DLBCLs. However, its impact on treatment outcome and prognosis is still not clearly defined.

METHODS

We compared the clinical outcomes between THRLBCL and DLBCL, not otherwise specified (NOS), in patients treated with rituximab plus cyclophosphamide, doxorubicin, vincristine and prednisone (R-CHOP).

RESULTS

Data from 11 patients with THRLBCL were matched to 33 patients with DLBCL-NOS. Patients were matched by five established prognostic factors of the International Prognostic Index, including age, Ann Arbor stage, Eastern Cooperative Oncology Group performance status, serum lactate dehydrogenase level and the number of extranodal involvement. There was no significant difference in the complete response rate to R-CHOP between THRLBCL (91%, 10/11) and DLBCL-NOS (97%, 32/33; p = 0.442). The 3-year event-free survival rate was 81% for both THRLBCL and DLBCL-NOS (p = 0.813). The 3-year overall survival rates were 75 and 81%, respectively (p = 0.719).

CONCLUSIONS

The treatment outcomes of THRLBCL are similar to those of DLBCL-NOS. The addition of rituximab to CHOP seems to be helpful for the management of THRLBCL, as it is for DLBCL-NOS.

T cell/histiocyte-rich large B-cell lymphoma: an update on its biology and classification

T cell/histiocyte-rich large B-cell lymphoma (THRLBCL), originally considered an uncommon variant of Diffuse Large B-Cell Lymphoma (DLBCL), is recognized by the World Health Organisation as a separate clinicopathological entity since 2008. It predominantly affects middle aged men often presenting with advanced stage disease frequently involving spleen, liver and bone marrow at time of diagnosis. According to the WHO, this lymphoma is morphologically characterized by less than 10% of large neoplastic B cells in a background of abundant T cells and frequently histiocytes. Differentiating THRLBCL from other lymphoproliferative disorders such as Nodular Lymphocyte Predominant Hodgkin Lymphoma (NLPHL) and Lymphocyte-Rich classical Hodgkin lymphoma (LRcHL) is important from a clinical point of view and can be achieved in most cases, given adequate biopsy specimens, by careful morphological and immunohistochemical evaluation of both the neoplastic cells as well as the nonneoplastic stromal component. According to this WHO definition, THRLBCL is still considered a clinically heterogeneous entity, though it is noted that especially the cases containing numerous histiocytes behave aggressively and show resistance to current therapies for DLBCL. Gene expression profiling studies of THRLBCL provided evidence for a prominent role for this histiocytic component that is important for a tolerogenic host immune response in which they may assist neoplastic cells in escaping the T cell-mediated immune surveillance. Therefore, reserving the diagnosis of THRLBCL to cases containing a large proportion of histiocytes might be relevant, as modulating their activity could provide new therapeutic options.

Therapy Outcome of a T-Cell-Rich-B-Cell Lymphoma (TCRBCL) Patient with R-CHOP in Ibadan, Nigeria: a Case Report

T-cell-rich B-cell lymphoma (TCRBCL) is considered a rare variant of aggressive B cell lymphoma characterized by few neoplastic B cells and a large reactive infiltrate with striking similarities to nodular lymphocyte predominant Hodgkin’s lymphoma.

A case of a 46 year old man referred with a 5 months history of generalized lymphadenopathy, weight loss, low grade pyrexia and two separately reported lymph node histology consistent with TCRBCL is described.

The clinical course was indeed aggressive because in spite of initial treatment with four cycles of CHOP combination chemotherapy, followed by R+CHOP(x 6 cycles), signs of tumor re-growth/infiltration were frequently observed. Also, recurrent infection was frequent, troublesome and eventually became overwhelming resulting to the loss of the patient.

This case, being the first case of TCRBCL diagnosed by immunohistochemical confirmation and managed at this centre with R-CHOP, is presented to highlight the dilemma in making diagnosis, clinical challenges faced and rituximab therapy outcome especially in resource poor country. It will also serve to increase our index of suspicion and the need reinforce immunohistochemistry in the diagnosis of lymphoma.

T-cell/histiocyte-rich large B-cell lymphoma shows transcriptional features suggestive of a tolerogenic host immune response

BACKGROUND

Gene expression profiling has successfully identified the prognostic significance of the host response in lymphomas. The aggressive T-cell/histiocyte-rich large B-cell lymphoma and the indolent nodular lymphocyte-predominant Hodgkin's lymphoma are both characterized by a paucity of tumor cells embedded in an overwhelming background. The tumor cells of both lymphomas share several characteristics, while the cellular composition of their microenvironment is clearly different.

DESIGN AND METHODS

We collected 33 cases of T-cell/histiocyte-rich large B-cell lymphoma and 56 cases of nodular lymphocyte-predominant Hodgkin's lymphoma and performed microarray gene expression profiling on ten cases of each lymphoma, to obtain a better understanding of the lymphoma host response. By quantitative reverse transcriptase polymerase chain reaction we verified that these 20 selected cases were representative of the entire population of T-cell/histiocyte-rich large B-cell and nodular lymphocyte-predominant Hodgkin's lymphomas.

RESULTS

We observed that the microenvironment in nodular lymphocyte-predominant Hodgkin's lymphoma is molecularly very similar to a lymph node characterized by follicular hyperplasia, while the microenvironment in T-cell/histiocyte-rich large B-cell lymphoma is clearly different. The T-cell/histiocyte-rich large B-cell lymphoma signature is hallmarked by up-regulation of CCL8, interferon-gamma, indoleamine 2,3 dioxygenase, VSIG4 and Toll-like receptors. These features may be responsible for the recruitment and activation of T cells, macrophages and dendritic cells, characterizing the stromal component of this lymphoma, and may point towards innate immunity and a tumor tolerogenic immune response in T-cell/histiocyte-rich large B-cell lymphoma.

CONCLUSIONS

The gene expression profile of T-cell/histiocyte-rich large B-cell lymphoma, in comparison with that of nodular lymphocyte-predominant Hodgkin's lymphoma, shows features suggestive of a distinct tolerogenic host immune response that may play a key role in the aggressive behavior of this lymphoma, and that may serve as a potential target for future therapy.

Diffuse aggressive B-cell lymphomas

Diffuse aggressive B-cell lymphomas comprise a relatively common and increasingly diverse group of neoplasms. Newer modalities including gene expression profiling and an increasing panel of immunohistochemical markers have contributed to greater accuracy in defining these entities. Attention is paid not only to the neoplastic cells but also to the cellular and stromal milieu in which they proliferate. These distinctions may have therapeutic implications as well, with improved outcome related to newer and sometimes targeted therapies. At the same time there is increasing understanding of the overlap, which occurs in the grey zone between diffuse large B-cell lymphoma and Burkitt lymphoma as well as between diffuse large B-cell lymphoma and Hodgkin lymphoma. This review aims to provide practical insights in the correct identification and differential diagnosis of these lymphomas, with emphasis on the changes that have occurred with the publication of the 2008 World Health Organization updated classification.

T-cell/histiocyte-rich B-cell lymphoma: Clinical presentation, management and prognostic factors: report on 61 patients and review of literature

T-cell/histiocyte-rich B-cell lymphoma (TC/HRBCL) is a rare subtype of diffuse large B-cell non-Hodgkin's lymphoma (DLBCL) with characteristic morphologic and immunophenotypic features, often misdiagnosed as Hodgkin's lymphoma and peripheral T-cell lymphoma. Few and conflicting clinical data are available in the literature addressing optimal treatment, prognosis and outcome. We retrospectively reviewed all patients diagnosed and managed at our institution between 1995 and 2004 diagnosed with T-cell-rich-B-cell lymphoma by WHO criteria. Sixty-one patients were identified. Initial pathology was incorrect in 82% of referred cases. The median age was 30 years. Seventy-one patients were males. Stage distribution was I - II in 21 patients, and III - IV in 40. Fifty-two percent of patients (32) had splenic involvement and thirty-seven patients (61%) presented with extranodal disease (22 >or= 2 sites). The International Prognostic Index (IPI) score was >or=2 in 62% of patients. All 59 newly diagnosed TC/HRBCL patients were treated with CHOP or R-CHOP combination chemotherapy +/- radiation therapy. The overall response rate was 85% and nine patients progressed on therapy. Fourteen patients relapsed with a median time of relapse of 6 months (range, 2 - 28). At a median follow-up of 22 months (range 1 - 132); 32 patients (52%) are alive with no evidence of disease. The 5-year overall survival and event free survival rates were 46% and 39% respectively. To conclude, TC/HRBCL is difficult to recognize without immunohistochemistry. It has an aggressive course and poor outcome; with most of patients presenting with advanced disease stage together with high IPI score. Treatment outcome seems to be similar to IPI matched DLBCL counterpart.

T-cell-rich B-cell lymphoma of the spleen presenting with severe hypersplenism

We report a 19-year-old woman who was presented with B-symptoms, massive splenomegaly, hepatomegaly and hypersplenism. She underwent diagnostic/therapeutic splenectomy. Microscopically, the spleen showed a vaguely micronodular and diffuse proliferation of lymphoid cells in the white pulp that also involved the red pulp. On immunohistochemical staining, this proliferation consisted predominantly of CD3(+), CD7(+) small T cells with the presence of a minor population of CD15(-),CD30(-), CD20(+) large atypical B cells. A liver biopsy also showed a similar morphology to that seen in the spleen. After splenectomy, only the pancytopenia improved. A combined immunochemotherapy regimen (rituximab, cyclophosphamide, doxorubicin, vincristine and prednisolone) was utilized, which resulted in a complete remission.

T-cell/histiocyte-rich B-cell lymphoma: biology, diagnosis, and management

T-cell/histiocyte-rich B-cell lymphoma (T/HRBCL) is an uncommon morphologic variant of diffuse large B-cell lymphoma (DLBCL). Pathologically, it is distinguished by <10% malignant B cells amid a majority population of reactive T lymphocytes and histiocytes. Diagnosis of this entity is occasionally difficult, as it may appear similar to other lymphoid diseases, such as nodular lymphocyte-predominant Hodgkin's lymphoma and classic Hodgkin's lymphoma. Accurate diagnosis therefore rests with careful immunohistochemical analysis of the tumor cells and the inflammatory microenvironment. Clinically, T/HRBCL occurs in younger patients, predominantly affects men, and involves the liver, spleen, and bone marrow with greater frequency than traditional DLBCL. Despite the unique clinical features and robust host inflammatory response, T/HRBCL follows a natural history similar to those of other DLBCLs and responds similarly to therapy. Recent gene expression analysis demonstrates that a productive relationship with the host immune response may extend beyond this small DLBCL variant to include as many as one third of all DLBCLs. At present, T/HRBCL should be treated similarly to other stage-matched DLBCLs, though future therapies will likely be targeted at the relationship of the tumor cells with their inflammatory microenvironment.

Familial nodular lymphocyte predominant Hodgkin lymphoma: Successful treatment with CHOP plus rituximab

Nodular lymphocyte-predominant Hodgkin lymphoma (NLPHL) is a rare tumor type distinct from classical Hodgkin lymphoma and its familial form is unusual. The two cases (mother at age 48 and son at age 30 years) of NLPHL in advanced clinical stage are described. The patients were successfully treated with an immunochemotherapy schedule consisting CHOP plus rituximab (CHOP-R). This chemotherapy was well tolerated and the patients reached complete remission. These remissions were for 34 and 40 months for mother and son, respectively. In patients with NLPHL, CHOP-R regimen should be used as an alternative treatment regimen to obtain a good long-lasting response without any adverse events.

Immunohistochemistry in bone marrow pathology: a useful adjunct for morphologic diagnosis

Pathomorphological examination of trephine biopsies of the bone marrow (BM) represents a standard method for the diagnosis and staging of hematologic neoplasms and other disorders involving the BM. The increasing knowledge about the genetic basis and biology of hematologic neoplasms, as well as the recently proposed WHO classification system, provide the framework for an accurate diagnosis. Although conventional morphology remains the gold standard for paraffin-embedded BM trephines, immunohistochemical stainings have become an integral part of the diagnostic workup. Antibodies suitable for paraffin sections are generally applicable to BM trephines, but modifications of staining protocols may be necessary due to the alternative fixatives and decalcification procedures used for BM biopsies. The indications for immunostainings range from confirmation and classification of lymphoma involvement, subclassification of acute leukemias, and estimating blast counts in myelodysplastic and myeloproliferative syndromes to characterization of BM involvement in nonhematologic neoplasms. Although subtyping of NHL in the BM is more difficult from the point of morphology, classification of the entities that frequently involve the BM, especially the small B-cell lymphomas, can easily be achieved with the help of immunohistochemistry. In this review, we try to summarize the current state of the art in BM immunohistochemistry for the diagnosis of hematologic disorders. Moreover, diagnostic algorithms and useful antibody panels are proposed for a rational and cost-effective approach.

Non-mediastinal grey zone lymphomas and report from the workshop

Grey zone lymphomas represent borderline lesions between classical Hodgkin lymphoma (cHL) and other morphologically and immunophenotypically related diseases and entities like nodular lymphocyte predominant HL, T-cell rich B-cell lymphoma, ALK-negative anaplastic large cell lymphoma (ALCL), diffuse large B cell lymphoma (DLBCL) anaplastic variant and primary mediastinal LBCL. The sharp definition of morphological, immunophenotypical and molecular features of the "text-book cases" of each disease and the comparison with grey zone cases has reduced most of the latter cases. Two reports in this workshop dealt with the problematic non-mediastinal grey zone lymphomas, one with a cHL of T cell-type presenting in the skin as a ALK-negative ALCL and the other with the grey zone between cHL of B-cell type and ALK-negative ALCL.

T-Cell/Histiocyte-Rich Large B-Cell Lymphoma Displays a Heterogeneity Similar to Diffuse Large B-Cell Lymphoma

T-cell/histiocyte-rich large B-cell lymphoma (THRLBCL), a proliferating peripheral B-cell neoplasm, is a morphologic variant of diffuse large B-cell lymphoma (DLBCL), which may be confused with Hodgkin's lymphoma, non-Hodgkin's lymphoma, and reactive lymphadenopathies. Though more recent studies suggested that it might be a distinct clinicopathologic entity and/or a heterogeneous entity with derivation from germinal center B cells, its histogenetic derivation remains controversial. The authors analyzed 30 cases of THRLBCL to further characterize the origin of the neoplastic cells using immunohistochemical and molecular studies for expression of Bcl-6, CD10, and CD138, as well as rearrangements of IgH/bcl-2 genes on paraffin-embedded tissue. Half of the cases (15/30) showed Bcl-6 expression and five cases (19%) showed CD10 expression, but none had CD138 expression (0/20). Only three cases showed coexpression of both Bcl-6 and CD10. Molecular studies performed in 21 cases detected rearrangement of immunoglobulin heavy gene in 18 cases, with none having detectable Bcl-2 gene rearrangement. These data indicate that similar to DLBCL, the cell origin of neoplastic cells in THRLBCL is composed of a heterogeneous group of proliferating peripheral B cells, with only some cases originating from germinal center B cells and others derived from heterogeneous origins. Lack of Bcl-2 gene rearrangements seems to argue against a possible progression from preexisting follicular lymphoma. Thus, the normal counterpart of the neoplastic cells cannot at this time be the sole basis for the subclassification of THRLBCL.

Aggressive B-cell lymphomas: a review based on the workshop of the XI Meeting of the European Association for Haematopathology

The generic term aggressive B-cell lymphoma includes a variety of entities, each with particular diagnostic and therapeutic issues. To define these entities better and to help confront such issues, a workshop was organized by the European Association of Haematopathology (EAHP) and the Society of Haematology during the XI Meeting of the EAHP, held in Italy in May 2002. Participants were asked to submit cases under various categories and all cases submitted were examined and reviewed by the panel members. The panel's diagnoses formed the basis for discussion at the workshop and a limited number of cases were selected to be presented in more detail and discussed during the workshop. After the workshop the panel met again to discuss the outcome, summarized in this report, which describes the panel's proposals regarding diagnostic criteria, terminology, the definition of new entities and evaluation of biological differential and new prognostic parameters.

T-cell-rich B-cell lymphoma presenting in the spleen: a clinicopathologic analysis of 3 cases

We review the clinical, pathologic, and molecular genetic features of 3 splenic T-cell-rich B-cell lymphomas and discuss their differential diagnosis. All patients presented with symptomatic splenomegaly and underwent diagnostic/therapeutic splenectomy. Microscopically, the spleen in all cases showed a micronodular proliferation of lymphoid cells. A proportion of the nodules demonstrated central hyalinization or sclerosis. There was also an exuberant extramedullary hematopoiesis. On immunohistochemical stain, the nodules consisted predominantly of small T cells with scattered large atypical B cells. The clonal nature of the atypical B cells was confirmed by polymerase chain reaction assays for immunoglobulin heavy-chain gene rearrangement. In the H&E sections, the differential diagnoses included Hodgkin's lymphoma, follicular lymphoma, peripheral T-cell lymphoma, and nonneoplastic granulomatous process. The presence of exuberant extramedullary hematopoiesis also raised the possibility of a chronic myeloproliferative disorder. The combined morphologic, immunohistochemical, and molecular genetic data are essential for a correct diagnosis of splenic T-cell-rich B-cell lymphoma.

Bone Marrow Involvement in Patients With Nodular Lymphocyte Predominant Hodgkin Lymphoma

The significance of bone marrow involvement in patients with nodular lymphocyte predominant Hodgkin lymphoma is unknown. Of 275 patients diagnosed as lymphocyte predominant Hodgkin lymphoma at our institution (1983-2003), we identified 7 patients with purely nodular disease in the diagnostic lymph node biopsy specimen who also had bone marrow involvement. The latter was detected at the time of initial diagnosis in four patients, after one cycle of chemotherapy in one patient, and at relapse in two patients. There were six men and one woman with a median age of 37 years (range, 25-47 years). In all cases, the bone marrow was involved by large B cells, representing <10% of all cells, associated with a prominent T-cell and histiocytic background. All patients had laboratory, radiologic, and/or morphologic evidence of aggressive disease at the time of detection of bone marrow involvement. At last follow-up, four patients had died of their disease and three were alive following therapy. In conclusion, a small subset of patients in whom lymph node biopsy shows nodular lymphocyte predominant Hodgkin lymphoma with a purely nodular pattern also may have lymphoma in the bone marrow. Bone marrow involvement is associated with laboratory, radiologic, or morphologic evidence of aggressive disease and poor prognosis. Although the best terminology for these bone marrow lymphomas is uncertain, the aggressive clinical behavior of these neoplasms supports the need for intensive therapy.

La maladie de Hodgkin nodulaire à prédominance lymphocytaire et ses diagnostics différentiels

Nodular lymphocyte predominance Hodgkin's disease (NLPHD), previously called nodular paragranuloma, is a rare entity recognized as a clinico-pathological entity distinct from classic Hodgkin's lymphoma. It is an indolent B cell lymphoma derived from a germinal center cell. NLPHD may closely resemble lymphocyte-rich classic Hodgkin's disease (LR-CHD) or T-cell or histiocyte-rich large B-cell lymphoma (TCRLBCL). A reproducible distinction between these entities is difficult but the classification is prognostically relevant. NLPHD is characterized by neoplastic "popcorn" cells CD20+ CD30- CD15- EMA+ Bcl6+ scattered within a nodular background predominantly composed of small B lymphocytes. LR-CHD neoplastic proliferation is composed of CD20+/- CD30+ CD15+/- EMA- Bcl6+/- Reed Sternberg or Hodgkin's cells, scattered within numerous CD3+ T cells. TCRLBCL is an agressive lymphoma composed of CD20+ CD30- CD15- EMA+/- Bcl6+/- polymorphic neoplastic cells, scattered within a mixture of CD3+ T cells and histiocytes. Epstein Barr virus is detectable within half cases of LR-CHD, but never in NLPHD and rarely in TCRLBCL. The transcription factors BOB1, PU-1, BSAP and IRF4 are new markers that could be useful for differential diagnosis.

T-cell-rich B-cell lymphoma: a clinicopathologic study of 21 cases and comparison with 43 cases of diffuse large B-cell lymphoma

Clinicopathologic features of 21 patients with T-cell-rich B-cell lymphoma (TCRBCL) were reviewed and compared to 43 patients with diffuse large B-cell lymphoma (DLBCL) to determine if there were distinguishing clinical characteristics and differences in response or survival to CHOP therapy. For the diagnosis of TCRBCL, the current WHO criteria was used. In all of our cases, the majority of cells are non-neoplastic T cells and <10% large neoplastic B cells are present. The initial pathologic diagnosis was nodular lymphocyte predominant Hodgkin's lymphoma (NLPHL) in two cases. Patients with TCRBCL were significantly younger (median: 46 years) and had a significantly higher incidence of B symptoms (62%), hepatomegaly (33%) and marrow infiltration (33%) at presentation when compared to DLBCL (P<0.03). The CR rate after treatment was 48% for TCRBCL patients versus 79% for the DLBCL (P<0.003). Although the CR rates in between the two groups are significant, the difference in 3 years survival rates in each CR groups was insignificant (80% versus 77%). The overall survival time in the two groups was 17 months. Event-free survival time in TCRBCL was 12 months, compared with 17 months in the DLBCL (P>0.05). The frequency of patients with TCRBCL achieving CR was 52.6% whereas that of patients with DLBCL was 79% (P<0.003). The TCRBCL 3 years event-free survival 48% and overall survival 64% were 63 and 72% for DLBCL, respectively.

Nodular lymphocyte-predominant Hodgkin lymphoma with nodules resembling T-cell/histiocyte-rich B-cell lymphoma: differential diagnosis between nodular lymphocyte-predominant Hodgkin lymphoma and T-cell/histiocyte-rich B-cell lymphoma

Nodular lymphocyte-predominant Hodgkin lymphoma (NLPHL) and T-cell/histiocyte-rich B-cell lymphoma (T/HRBCL) are distinct tumors and are treated differently. They are linked by a morphologic and probably a biologic continuum, which renders the differential diagnosis difficult. To develop criteria to distinguish the entities along the morphologic continuum, we correlated the lymph node architecture and immunophenotype of both tumor cells and reactive components of 235 neoplasms in the spectrum of NLPHL and T/HRBCL with clinical data. Two hundred and eighteen cases fitted the World Health Organization (WHO) criteria of NLPHL (139) or T/HRBCL (79). While tumor cells in both entities were immunophenotypically similar, background composition differed: in NLPHL small B cells and CD3+CD4+CD57+ T cells were common, whereas in T/HRBCL, CD8+ cytotoxic T cells and histiocytes dominated. Follicular dendritic cells (FDCs) formed expanded meshworks in NLPHL, whereas they were absent in T/HRBCL. Seventeen cases represented a gray zone: within FDC meshworks, neoplastic B cells resided in a background depleted of small B cells but rich in T cells and histiocytes. Tumor cells either were loosely scattered or formed clusters, thus resembling areas of either T/HRBCL or inflammatory diffuse large BCL (DLBCL) within the nodules. Patients with these NLPHLs with T-cell/histiocyte-rich nodules presented at a high stage and with B symptoms, as in T/HRBCL, but had an excellent survival, as in NLPHL. This morphologic pattern suggests a biologic continuum between NLPHL and T/HRBCL.

T-cell/histiocyte-rich large B-cell lymphomas and classical diffuse large B-cell lymphomas have similar outcome after chemotherapy: a matched-control analysis

PURPOSE

Because it is unclear whether T-cell/histiocyte-rich large B-cell lymphomas (H/TCRBCL) should be considered as a true clinicopathologic entity, we conducted a matched-control analysis comparing patients with H/TCRBCL and patients with diffuse large-B cell lymphoma (B-DLCL).

PATIENTS AND METHODS

More than 4,500 patients were enrolled onto non-Hodgkin's lymphoma trials conducted by the Groupe d'Etude des Lymphomes de l'Adulte. After histologic review, 50 patients were subclassified as H/TCRBCL. They were matched to 150 patients with B-DLCL for each of the factors of the International Prognostic Index (IPI).

RESULTS

Clinical characteristics of H/TCRBCL patients showed a male predominance and a median age of 47 years. Performance status was normal in 89% of patients, whereas lactate dehydrogenase level was increased in 60% of patients. The disease was disseminated in 81% of patients, and 48% had two or more involved extranodal sites. The IPI score was >or= 2 in 53% of patients. The complete response rate to chemotherapy was 63%, and 5-year overall survival (OS) and event-free survival (EFS) rates (mean +/- SD) were 58% +/- 18% and 53% +/- 16%, respectively. The matched-control analysis showed a trend toward a better response to chemotherapy for patients with B-DLCL (P =.06), whereas no difference was observed in OS (P =.9) and EFS (P =.8).

CONCLUSION

H/TCRBCL is an aggressive disease that often presents with adverse prognostic factors. However, when treatment is adapted to the disease risk, outcome is equivalent to that observed in patients with B-DLCL. Thus H/TCRBCL should be considered a pathologic variant that belongs to the B-DLCL category.

Diffuse large B-cell lymphoma: one or more entities? Present controversies and possible tools for its subclassification

Diffuse large B-cell lymphoma (DLBCL) is the commonest type of lymphoid tumour world-wide. This category was included both in the REAL and WHO Classification aiming to lump together all malignant lymphomas characterized by the large size of the neoplastic cells, B-cell derivation, aggressive clinical presentation, and the need for highly effective chemotherapy regimens. These tumours are detected as primary or secondary forms both at the nodal and extranodal levels, in immunocompetent hosts as well as in patients with different types of immunosuppression. They display a significant variability in terms of cell morphology and clinical findings, which justifies the identification of variants and subtypes. Among the latter, the primary mediastinal one does actually correspond to a distinct clinicopathological entity. Immunophenotypic, tissue microarray and molecular studies underline the extreme heterogeneity of DLBCLs and suggest a subclassification of the tumour, based on the identification of different pathogenic pathways, which might have much greater relevance than pure morphology for precise prognostic previsions and adoption of ad hoc therapies. The more recent acquisitions on the pathobiology of DLBCLs are reviewed in the light of the authors' experience, aiming to contribute to the existing debate on the topic.

T-cell/histiocyte-rich large B-cell lymphoma: a heterogeneous entity with derivation from germinal center B cells

T-cell/histiocyte-rich large B-cell non-Hodgkin's lymphoma (THRLBCL) is an unusual morphologic variant of diffuse large B-cell lymphoma. We reviewed 30 cases of THRLBCL to evaluate its heterogeneity based on morphologic, immunophenotypic, and genetic features. Cases were classified according to the appearance of the large neoplastic B cells into three morphologic variants: 1) lymphocytic and histiocytic (L&H-like) (resembling the L&H cells of nodular lymphocyte predominance Hodgkin's lymphoma (14 cases); 2) centroblast (or immunoblast)-like (10 cases), and 3) Reed-Sternberg cell-like (resembling the neoplastic cells of classic Hodgkin's lymphoma) (6 cases). We used a panel of immunohistochemical stains, including those with specificity for germinal center B cells: CD20, CD79a, CD30, CD15, epithelial membrane antigen, BCL-2, BCL-6, and CD10. The /JH polymerase chain reaction assay was further performed to investigate a relationship to follicular lymphoma. The results were correlated with Epstein-Barr virus status as determined by staining for latent membrane protein and EBER-1 in situ hybridization. All cases were of B-cell immunophenotype with strong surface CD20 reactivity in the neoplastic large lymphoid cells, although CD79a was more inconsistently and weakly expressed (10 of 17). Nuclear positivity for the BCL-6 protein was detected in the tumor cells in 26 of 29 (90%) cases. However, differences in expression of other antigens were encountered in the histologic subtypes. Epithelial membrane antigen positivity, a feature often seen in nodular lymphocyte predominance Hodgkin's lymphoma, was observed in 11 of 30 (37%) cases and was most commonly seen in cases with L&H cell morphology (8 of 14; 57%). CD30 expression was observed in 9 of 30 (30%) cases but was most frequent in cases with Reed-Sternberg-like morphology (3 of 6 [50%]). CD10 expression was infrequent overall (3 of 29; 10%), with 2 of 3 positive cases identified in the centroblastic group. The overall rarity of positivity for CD10, BCL-2 (3 of 22; 13%), and -2 JH rearrangement (1 of 28; 4%) indicates a lack of connection to follicular lymphoma for all subtypes. The three cases that were negative for BCL-6 protein were LMP-1 positive and EBER-1 positive by in situ hybridization, and 2 of 3 had neoplastic cells with Reed-Sternberg-like morphology. These results demonstrate that although a large proportion of THRLBCL represent tumors of germinal center B cell derivation, they exhibit a diversity of morphologic and immunophenotypic features. A subset of THRLBCL may be related to nodular lymphocyte predominance Hodgkin's lymphoma. A small percentage show features closely resembling classic Hodgkin's lymphoma and could be considered a variant of grey zone lymphoma.

T-cell/histiocyte-rich large B-cell lymphoma is a disseminated aggressive neoplasm: differential diagnosis from Hodgkin's lymphoma

AIMS

An accurate diagnosis of T-cell/histiocyte-rich large B-cell lymphoma needs to take into consideration those forms of Hodgkin's lymphoma also characterized by a predominance of small lymphocytes and histiocytes, i.e. nodular lymphocyte predominance Hodgkin's lymphoma and lymphocyte-rich classical Hodgkin's lymphoma. We have studied the clinical, phenotypic and genetic features of a series of 12 cases of T-cell/histiocyte-rich large B-cell lymphoma along with 18 cases of Hodgkin's lymphoma for comparative purposes.

METHODS AND RESULTS

Of the Hodgkin's lymphoma cases, there were 11 lymphocyte predominance type and seven classic type. T-cell/histiocyte-rich large B-cell lymphomas presented usually in advanced stages (III or IV in 11/12 cases), frequently with 'B' symptoms (6/9 cases), and followed a more aggressive course than Hodgkin's lymphoma (4/8 patients died due to the tumour in T-cell/histiocyte-rich large B-cell lymphoma versus 0/15 in Hodgkin's lymphoma). T-cell/histiocyte-rich large B-cell lymphoma cases showed diffuse effacement of the nodal architecture by a proliferation of scattered large atypical B-cells obscured by a background of small T-lymphocytes (more CD8+, TIA1+ than CD57+). Five cases showed also a prominent histiocytic component. The large B-cells expressed CD45 and often EMA (6/10 cases). On the other hand, CD 30, CD15 and latent infection by Epstein-Barr virus (EBV) were generally lacking. bc l6 and CD10 were, respectively, detected in 6/6 and 1/5 cases. Conventional polymerase chain reaction (PCR) showed monoclonal immunoglobulin heavy chain (IgH) gene rearrangements in all T-cell/histiocyte-rich large B-cell lymphomas studied (5/5), but did not detect any case with t(14;18) involving the major breakpoint region (0/4).

CONCLUSIONS

The differential diagnosis of T-cell/histiocyte-rich large B-cell lymphoma from Hodgkin's lymphoma is facilitated by the integration of different immunophenotypic, molecular and clinical findings. T-cell/histiocyte-rich large B-cell lymphoma is a monoclonal neoplasm of bc l6+ B-cells with a phenotypic profile similar to lymphocyte predominance Hodgkin's lymphoma, suggesting a germinal centre origin and a possible relation to this disease. Therefore, in order to distinguish it from lymphocyte predominance Hodgkin's lymphoma, characterization of the reactive background, IgH gene rearrangement studies by conventional PCR and clinical features are more useful. In contrast, T-cell/histiocyte-rich large B-cell lymphoma can be distinguished from classical Hodgkin's lymphoma thanks to the presence of monoclonal IgH rearrangement and the CD 30-CD15-CD45+EMA+ immunophenotypic profile of the neoplastic cells in T-cell/histiocyte-rich large B-cell lymphoma.

T-cell rich B-cell lymphoma: clinical distinctiveness and response to treatment in 45 patients

T-cell rich B-cell lymphoma (TCR-BCL) is a recently described pathologic diagnosis without a place among traditional lymphoma classification systems. In the past, TCR-BCL has been included among other diagnoses, in particular lymphocyte predominant Hodgkin's disease (LPHD). The study of TCR-BCL cohorts may elucidate clinical distinctiveness, response to therapy, and the effect of treatment regimen on outcome. Between 1992 and 1997, a hematopathologist at Memorial Sloan-Kettering Cancer Center (MSKCC) diagnosed 45 patients with TCR-BCL according to published criteria. Clinical data was collected through retrospective chart review and communication with other patient providers. Our patients presented most commonly as males in their fourth decade with advanced stage disease. Three-year overall survival (OS) and failure-free survival (FFS) were 73 and 37%, respectively. Conventional combination chemotherapy regimens were utilized for an aggressive non-Hodgkin's lymphoma (NHL) diagnosis in 26 and for a Hodgkin's disease (HD) diagnosis in 10. Disease-free survival (DFS) was significantly better for NHL (36%) vs. HD (10%) directed chemotherapy at 3 years (p = 0.003). Overall survival at 3 years was not statistically different (62 vs. 79%) due to successful salvage therapy in both groups. It is important to distinguish TCR-BCL from LPHD and classical HD. Advanced stage, extranodal disease, involvement of the mediastinum, mesentery and/or spleen are clinical clues to a TCR-BCL diagnosis. Chemotherapy directed to a NHL diagnosis rather than HD results in a significant improvement in disease-free survival. Initial Hodgkin's disease-directed (HD-directed) chemotherapy should be avoided, although salvage transplantation may result in prolonged survival.

T-cell-rich B-cell lymphoma - diagnostic and therapeutic aspects

BACKGROUND

Morphologically, T-cell-rich B-cell lymphoma (TCRB-NHL) may be indistinguishable from Hodgkin's disease (HD). Immunophenotyping may be helpful in the separation of these entities. TCRB-NHL is occasionally misdiagnosed and treated as HD. However, information is limited regarding clinical characteristics and outcome of this patient population. Furthermore, knowledge concerning any association with Epstein-Barr virus (EBV) in TCRB-NHL, as well as the immunophenotype of reactive T-cells and the expression of T-cell intracellular antigen-1 (TIA-1), granzyme B (GrB) and the CD3-zeta-chain is limited.

PATIENTS AND METHODS

We have re-evaluated 251 tumour biopsies from patients aged > or =15 years with HD diagnosed 1985-1994. Reclassification from HD to TCRB-NHL was done in 12 cases (5%). Six TCRB-NHL patients initially diagnosed and treated as B-NHL were also included. All TCRB-NHL biopsies were analysed for latent membrane protein 1 (LMP-1), CD4, CD8, CD56, CD57, TIA-1, GrB and CD3-zeta-chain.

RESULTS

Twelve cases of TCRB-NHL were initially subclassified as HD (lymphocyte predominance 5, nodular sclerosis 3, and mixed cellularity 4). Of these 12 TCRB-NHL patients, 6 were given radiotherapy alone, 5 MOPP/ABVD or similar combination chemotherapy, and one patient combined modality treatment. Male sex (p<0.05) and inguinal involvement (p<0.001) were significantly more frequent when TCRB-NHL patients receiving HD treatment (n=12) were compared with the remaining patients with confirmed (conf) HD, while no significant differences were seen with regard to stage, bone marrow infiltration, splenomegaly or cause-specific survival. Similar results were achieved when all TCRB-NHL patients (n=18) were compared to conf HD patients. Lymphoma cells in three samples stained positively for LMP-1. A decreased expression of CD3-zeta-chain was seen in 9/14 tumour biopsies.

CONCLUSION

Immunohistochemistry makes it possible to identify cases of TCRB-NHL that are morphologically difficult to distinguish from HD. The outcome of TCRB-NHL patients treated as having HD was comparable with that of the remaining HD population.

T-cell/histiocyte-rich large B-cell lymphoma: a distinct clinicopathologic entity

PURPOSE

Although it has proven difficult to delineate diagnostically reproducible and clinically relevant subgroups, the heterogeneity of diffuse large B-cell lymphomas (DLBCL) is widely acknowledged. In 1992, we reported on six cases that suggested that large B-cell lymphoma rich in stromal histiocytes and T cells may be identified as a distinct clinicopathologic entity within DLBCL.

PATIENTS AND METHODS

An integrated clinicopathologic study of 40 cases of this DLBCL subtype is presented.

RESULTS

Distinguishing a DLBCL rich in histiocytes and reactive T cells, designated T-cell/histiocyte--rich large B-cell lymphoma (THR-BCL), may be justified from a clinical point of view. The disease typically affects middle-aged male patients who usually present with advanced-stage disease that is not adequately managed with current therapeutic strategies. Whereas proliferation fraction and p53 overexpression, in addition to the clinical variables incorporated in the International Prognostic Index (IPI), significantly correlate with response to treatment and survival in a univariate analysis, only the IPI score identifies relevant prognostic THR-BCL subpopulations in a multivariate model. The morphologic and immunophenotypic profile of the neoplastic B cells in THR-BCL suggests that they may originate from a germinal center ancestor.

CONCLUSION

THR-BCL constitutes a distinct clinicopathologic entity that is characterized by an aggressive behavior. Experimental therapeutic strategies may be indicated to obtain a more favorable response to treatment in this disease.

Histiocyte-rich, T-cell-rich B-cell lymphoma: a distinct diffuse large B-cell lymphoma subtype showing characteristic morphologic and immunophenotypic features

AIMS

The clinicopathological features of histiocyte-rich, T-cell-rich B-cell lymphoma (HRTR-BCL) were first recognized in 1992. In this study, 60 cases of HRTR-BCL were analysed in order to provide a detailed morphological and immunophenotypical profile of the disorder.

METHODS AND RESULTS

HRTR-BCL is easily distinguished from other B-cell lymphomas rich in stromal T-cells by (i) a diffuse or vaguely nodular growth pattern, (ii) the presence of a minority population of CD15-, CD20+ large neoplastic B-cells, (iii) a prominent stromal component composed of both T-cells and non-epithelioid histiocytes, and (iv) the scarcity of small reactive B-cells. These criteria also enable a reliable distinction from lymphocyte-rich classical Hodgkin's lymphoma (CHL), from lymphocyte-predominant Hodgkin's lymphoma (LPHL), paragranuloma type and from peripheral T-cell lymphoma. Based on the morphology of the neoplastic cells and on their frequent bcl-6 immunoreactivity, we speculate that HRTR-BCL may be derived from a progenitor cell of germinal centre origin.

CONCLUSIONS

HRTR-BCL presents characteristic clinical features, affecting predominantly middle-aged men who present with advanced stage disease and are at high risk of treatment failure. Considering these distinctive clinicopathological features, recognizing HRTR-BCL as a lymphoma entity may be justified.

Durable remission in recurrent T-cell-rich B-cell lymphoma with the anti-CD20 antibody rituximab

A diagnostic continuum exists between lymphocyte-predominant Hodgkin's disease, T-cell-rich B-cell lymphoma (TCRBCL), and diffuse large B-cell lymphoma. While TCRBCLs are uncommon, their clinical and morphologic presentation can mimic other Hodgkin's and non-Hodgkin's lymphomas from which they must be distinguished for diagnosis and treatment. We present an unusual case of a 30-year-old man with recurrent TCRBCL arising from lymphocyte-predominant Hodgkin's disease with remarkable response to treatment with the anti-CD20 antibody, rituximab.

Feline Hodgkin's-like lymphoma: 20 cases (1992-1999)

We identified 20 cases of feline lymphadenopathy that conform to many clinical and histologic manifestations of human Hodgkin's disease. Histologic subtypes encountered included lymphocyte predominance (nine cases), mixed cellularity (nine cases), and nodular sclerosis (two cases). Two cases were not easily classified; fibrous bands were present, but the absence of nodules supported a subclassification of mixed cellularity Hodgkin's disease. Immunohistochemical staining of the tissues using antibodies against the pan T-cell antigen CD3, the human B-lymphocyte antigen 36 (BLA.36), the pan B-lymphocyte and plasma cell marker CD79a, and a myeloid antigen (MAC387) confirmed the phenotypic heterogeneity of the tumor. Classic Reed-Sternberg (RS) cells and mononuclear, multinucleate, and lacunar cell variants did not stain with any of the antibodies used. In contrast, lymphohistiocytic RS variants (L+H cells) reacted positively to BLA.36 and CD79a B-cell markers. Eighteen of 20 affected cats were > or = 6 years of age (range, 1-14 years). A sex predilection could not be identified. These findings support the existence of Hodgkin's-like lymphoma in the cat. Proper identification of this disease in the cat will enable further characterization of clinical features and biologic behavior to determine whether there are significant differences in the treatment and prognosis of feline Hodgkin's-like lymphoma compared with non-Hodgkin's lymphoma.

Prognostic significance of tumour-infiltrating T lymphocytes and T-cell subsets in de novo diffuse large B-cell lymphoma: a multiparameter flow cytometry study

Tumour-infiltrating T lymphocytes (TIL-T) have been implicated in playing a role in controlling tumour growth. We evaluated TIL-T in 55 cases of de novo diffuse large B-cell lymphoma (DLBCL) using three- or four-colour flow cytometric immunophenotyping (FCI). The percentage of TIL-T varied from 3% to 72% of total viable cellular events (mean 32 +/- 20%). The CD4:CD8 ratio varied from 0.17 to 13 (mean 2.3 +/- 2.2). Cases with >/= 20% T cells and those with CD4:CD8 ratios > or = 2.0 showed a significantly better overall survival (P = 0.017 and P = 0.034 respectively). These findings were independent of clinical stage at diagnosis. The T-cell percentage and CD4:CD8 ratio were moderately correlated (Spearman correlation coefficient = 0.47, P = 0.001) and multivariate analysis revealed that the association of the two factors with prognosis was mutually dependent. The T cells in 23 cases were studied for CD45RO. The mean percentage of total T cells expressing CD45RO was 86 +/- 10%. There was a trend towards better survival for those patients with a higher percentage of CD45RO+ T cells (P = 0.06). These results suggest that TIL-T, particularly CD4+ T cells, may play a role in the control of DLBCL, and measurement of T-cell percentage and T-cell subsets using FCI may be useful in predicting the clinical behaviour of DLBCL.

Primary cutaneous T-cell-rich B-cell lymphoma: clinically distinct from its nodal counterpart?

The cases of two patients with Stage IE primary cutaneous T-cell-rich B-cell lymphoma (TCRBCL) are described. In both, the lesion showed a dense infiltrate by numerous small T lymphocytes with scattered histiocytes and large atypical B-lymphoid cells. Polymerase chain reaction assays demonstrated that the B cells were monoclonal, with immunoglobulin heavy-chain gene rearrangement. No clonal rearrangements of the T-cell receptor gamma gene were observed. Both patients were disease-free at 4 months and at 5 years after therapy, respectively. Although rare, primary cutaneous T-cell-rich B-cell lymphoma appears to have a better prognosis than its nodal counterpart, with or without skin involvement.

T-cell-rich large B-cell lymphoma in children and adolescents: a clinicopathologic report of six cases from the Children's Cancer Group Study CCG-5961

BACKGROUND

T-cell-rich large B-cell lymphoma (TCRLBCL) is a morphologic subset of diffuse large B-cell lymphoma that has been confused with Hodgkin disease and reactive lymphadenopathies. To the authors' knowledge the majority of reports of TCRLBCL are from adults, and it is not widely recognized as occurring in the pediatric population. The current study reports a cohort of six cases of TCRLBCL from the Children's Cancer Group CCG-5961 study.

METHODS

Biopsies from patients entered on CCG-5961 were submitted for central pathology review and immunophenotyping. Six cases of TCRLBCL were identified and correlated with clinical characteristics.

RESULTS

Of 86 cases centrally reviewed to date on CCG-5961, 20 (23%) were diagnosed as diffuse large B-cell lymphomas. Of these, 6 cases (7% of total cases and 30% of large B-cell cases) were TCRLBCL, based on a diffuse growth pattern with a minor population of neoplastic large B cells and an associated extensive reactive T-cell infiltrate. All patients with TCRLBCL were males ages 12-16 years. Three patients with TCRLBCL had advanced stage disease. No bone marrow or central nervous system involvement was detected in any case.

CONCLUSIONS

TCRLBCL is a morphologic subtype of diffuse large B-cell lymphoma that may be difficult to recognize due to the extensive infiltrate of reactive T cells. This entity is not well recognized in pediatric patients, but in the current study represented 7% of all cases and 30% of large B-cell lymphomas received for central review from the ongoing CCG-5961 protocol. Because TCRLBCL may be confused with Hodgkin disease and reactive lymphadenopathies, it is essential that this entity be recognized in the pediatric age group.

Nijmegen breakage syndrome-associated T-cell-rich B-cell lymphoma: case report

In 1981 Weemaes et al. first described the Nijmegen breakage syndrome (NBS), a rare autosomal recessive disorder characterized by stunted growth, microcephaly, immunodeficiency, spontaneous chromosome instability, and a peculiar predisposition to cancer development. Most NBS-related malignancies are lymphomas, but their pathologic features have rarely been specified. We report here the case of a northern Italian 8-year-old child who, 2 years after the diagnosis of NBS, developed a diffuse large B-cell lymphoma (T cell-rich B-cell lymphoma variant). The histological and immunobiological features of the lymphoma population are analyzed and discussed in detail.

T-cell-rich B-cell non-Hodgkin's lymphoma mimicking Hodgkin's disease

We report on a patient with recurrent T-cell-rich B-cell lymphoma (TCRBCL), initially misdiagnosed as a lymphocyte-rich Hodgkin's disease. This case exemplifies the diagnostic problems of TCRBCL and the need for immunophenotypic analysis to differentiate TCRBCL from Hodgkin's disease, nodular paragranuloma and peripheral T-cell lymphoma. A rather unusual aspect is the long disease-free interval between the excision of the node in and the late relapse in 1996. The significance of the abundant T-cell infiltration in this B-cell neoplasm will be discussed and the concepts concerning antitumor response will be reviewed. Based on epidemiological data and the clinical behaviour TCRBCL does not seem to represent a distinctive pathological entity.

The many faces of Hodgkin's disease around the world: what have we learned from its pathology?

In the past decade there have been many advances in our understanding of Hodgkin's disease. Among the most important is the discovery that the Reed-Sternberg cell is a lymphoid cell, in most cases a B cell, and that it is clonal, and thus a true lymphoma, deserving of a name change, to 'Hodgkin's lymphoma' (HL). Based on a combination of immunophenotype and morphology, the R.E.A.L. Classification recognizes two main types of HL: classical types (nodular sclerosis, mixed cellularity, lymphocyte-rich classical HL, and lymphocyte depletion) and nodular lymphocyte predominance type (NLPHL), which probably represent distinct biological entities. The immunophenotype and genetic features of both classical HL and NLPHL have been defined. These are useful in the subclassification of HL and in distinguishing HL from two recently-described, aggressive lymphomas that were in the past often diagnosed as HL: anaplastic large-cell lymphoma, T-cell type (ALCL), and T-cell/histiocyte-rich large B-cell lymphoma (T/HRBCL). Epstein-Barr virus has been detected in approximately 40% of the cases of classical HL, and is clonal, suggesting that this virus may play a role in the pathogenesis of at least some types of HL. The frequency of HL varies in different populations, and the frequency of EBV-positive HL appears to be inversely related to the overall frequency of HL in a given population. Thus, it is possible that its presence may simply reflect the prevalence of EBV-infected B cells in the individual. Despite the advances of the past ten years, many questions remain to be answered, and these will provide the challenges of the next decade.

T-cell-rich large-B-cell lymphomas contain non-activated CD8+ cytolytic T cells, show increased tumor cell apoptosis, and have lower Bcl-2 expression than diffuse large-B-cell lymphomas

The factor(s) responsible for the reduced B cell number and increased T cell infiltrate in T-cell-rich large-B-cell lymphomas (TCRBCLs) have not been well characterized. We studied 18 TCRBCLs and 12 diffuse large-B-cell lymphomas (DLBCLs) to compare the 1) predominant T cell subpopulation(s), 2) expression of cytotoxic granule proteins (TIA-1 and granzyme B), 3) level of tumor cell apoptosis (Apoptag system, Oncor, Gaithersburg, MD), and 4) expression of Ki-67 (Mib-1) and apoptosis-related proteins (fas (CD95), bcl-2, and p53). T cells in TCRBCLs and DLBCLs were predominantly CD8+ T cells expressing alphabeta T-cell receptors and TIA-1 (16 of 18 TCRBCLs with >50% TIA-1+ small lymphocytes) but lacking granzyme B (16 of 18 TCRBCLs with <25% granzyme B+ small lymphocytes). Scattered apoptotic tumor cells (confirmed with CD20 co-labeling) were present in 15 of 18 TCRBCLs, with 14 of 15 cases having <10% apoptotic cells. No apoptotic cells were seen in 12 of 12 DLBCLs. In 16 of 16 immunoreactive TCRBCLs, <25% tumor cells were bcl-2+, whereas 6 of 12 DLBCLs had >50% bcl-2+ tumor cells. CD95 (fas) expression was also lower, with 3 of 18 (16.7%) TCRBCLs versus 4 of 12 (33%) DLBCLs having >25% CD95+ tumor cells. TCRBCLs and DLBCLs had similar levels of p53 and Ki-67 (Mib-1) expression. Thus, T cells in TCRBCLs are non-activated cytotoxic T lymphocytes (TIA-1+, granzyme B-). Tumor cell apoptosis (perhaps cytotoxic T cell mediated) may partly account for the decreased number of large (neoplastic) B cells in TCRBCLs, but other factors (ie, decreased bcl-2 expression) may also be needed.

Pathological findings in human autoimmune lymphoproliferative syndrome

The defects in lymphocyte apoptosis that underlie the autoimmune lymphoproliferative syndrome (ALPS) are usually attributable to inherited mutations of the CD95 (Fas) gene. In this report, we present the histopathological and immunophenotypic features seen in the lymph nodes (n = 16), peripheral blood (n = 10), bone marrow (n = 2), spleen (n = 3), and liver (n = 2) from 10 patients with ALPS. Lymph nodes showed marked paracortical hyperplasia. Interfollicular areas were expanded and populated by T cell receptor-alphabeta CD3+ CD4-CD8- (double-negative, DN) T cells that were negative for CD45RO. CD45RA+ T cells were increased in all cases studied. The paracortical infiltrate was a result of both reduced apoptosis and increased proliferation, as measured by in situ detection of DNA fragmentation and staining with MIB-1, respectively. The paracortical proliferation may be extensive enough to suggest a diagnosis of malignant lymphoma. Many of the paracortical lymphocytes expressed markers associated with cytotoxicity, such as perforin, TIA-1, and CD57. CD25 was negative. In addition, most lymph nodes exhibited florid follicular hyperplasia, often with focal progressive transformation of germinal centers; in some cases, follicular involution was seen. A polyclonal plasmacytosis also was present. The spleens were markedly enlarged, more than 10 times normal size. There was expansion of both white pulp and red pulp, with increased DN T cells. DN T cells also were observed in liver biopsies exhibiting portal triaditis. In the peripheral blood, the T cells showed increased expression of HLA-DR and CD57 but not CD25. CD45RA+ T cells were increased in the four cases studied. Polyclonal B cell lymphocytosis with expansion of CD5+ B cells was a characteristic finding. Taken together, the histopathological and immunophenotypic findings, particularly in lymph nodes and peripheral blood, are sufficiently distinctive to suggest a diagnosis of ALPS. Of note, two affected family members of one proband developed lymphoma (T-cell-rich B-cell lymphoma and nodular lymphocyte predominance Hodgkin's disease, respectively).

Differential diagnosis between classic Hodgkin's lymphoma, T-cell-rich B-cell lymphoma, and paragranuloma by paraffin immunohistochemistry

There are significant difficulties in the differential diagnosis of lymphomas at the interface between classic Hodgkin's lymphoma and both paragranuloma and T-cell-rich B-cell lymphoma as well as at the interface between T-cell-rich B-cell lymphoma and paragranuloma. We therefore investigated 197 cases (155 classic Hodgkin's lymphomas, 32 T-cell-rich B-cell lymphomas, and 10 paragranulomas) by paraffin immunohistochemistry. Special interest was given to cases with a B-cell phenotype of tumor cells. The reactive inflammatory infiltrate in both classic Hodgkin's lymphoma and T-cell-rich B-cell lymphoma was rich in TIA-1-positive cytolytic lymphocytes, and CD57-positive cells were rarely encountered. In contrast, in paragranuloma CD57-positive cells and small B-lymphocytes predominated the background infiltrate. The tumor cells in cases of classic Hodgkin's lymphoma were positive for CD30 in 95%, for CD15 in 75%, and for CD20 in 22%. Apart from this, vimentin was expressed in >95% of the cases. All cases of T-cell-rich B-cell lymphoma were negative for vimentin, CD30, and CD15. The reactivity of the tumor cells for CD30, CD15, CD20, and vimentin together with the background reactivity for CD57 and TIA-1 seem to reliably discriminate between the entities and should therefore help to increase the interobserver reproducibility of diagnoses in the gray zone around Hodgkin's lymphoma.