T-cell-rich B large-cell lymphoma simulating lymphocyte-rich 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.

Pathobiology of hodgkin lymphoma

Despite its well-known histological and clinical features, Hodgkin's lymphoma (HL) has recently been the object of intense research activity, leading to a better understanding of its phenotype, molecular characteristics, histogenesis, and possible mechanisms of lymphomagenesis. There is complete consensus on the B-cell derivation of the tumor in most cases, and on the relevance of Epstein-Barr virus infection and defective cytokinesis in at least a proportion of patients. The REAL/WHO classification recognizes a basic distinction between lymphocyte predominance HL (LP-HL) and classic HL (cHL), reflecting the differences in clinical presentation and behavior, morphology, phenotype, and molecular features. cHL has been classified into four subtypes: lymphocyte rich, nodular sclerosing, with mixed cellularity, and lymphocyte depleted. The borders between cHL and anaplastic large-cell lymphoma have become sharper, whereas those between LP-HL and T-cell-rich B-cell lymphoma remain ill defined. Treatments adjusted to the pathobiological characteristics of the tumor in at-risk patients have been proposed and are on the way to being applied.

Morphologic, immunphenotypic and clinical discriminators between T-cell/histiocyte-rich large B-cell lymphoma and lymphocyte-predominant Hodgkin lymphoma

BACKGROUND

Features of T-cell/histiocyte rich large B-cell lymphoma (THRLBCL) overlap with those of lymphocyte predominant Hodgkin lymphoma (LPHL). The two lymphomas may represent a spectrum of the same disease, and differentiation between the two can sometimes be difficult. We looked at histomorphologic, immunophenotypic and clinical information that may help differentiate the two entities.

METHODS

Cases of THRLBCL and LPHL were blindly reviewed and studied for histological pattern (nodular vs. diffuse), nuclear features and pattern of expression of CD20, CD30, CD57, epithelial membrane antigen (EMA) and Epstein-Barr virus (EBV). A score encompassing diffuse histology, high nuclear grade, CD20 single-cell pattern, CD30+, CD57-, EMA-, and EBV+ was estimated for the diagnosis of TCHRLBCL.

RESULTS

There were 58 cases, including 30 cases of TCHRLBL and 28 cases of LPHL. The median age was 36 years for TCHRLBCL and 21 years for LPHL (P = 0.0001). Three types of nuclei were identified (lymphocytic/histocytic, Reed-Sternberg and centroblast-like). The latter two high-grade nuclei were suggestive of TCHRLBCL. TCHRLBCL and LPHL, respectively, showed diffuse histology, 90% vs. 4% (P = 0.001), single CD20+ cells, 93% vs. 3.5% (P = 0.00004), CD30+ cells, 30% vs. 0% (P = 0.01), CD57+ cells, 41% vs. 93% (P = 0.008), EMA+ cells, 27% vs. 60% (P = 0.113), EBV+ cells, 24% vs. 0% (P = 0.117), high nuclear grade, 70% vs. 0% (P = 0.001), total score 2-7 (mean 4.68) vs. 0-2 (mean 0.72) (P = 0.001), high stage, 86% vs. 7% (P = 0.0001).

CONCLUSION

Our findings indicate that a combination of multiple parameters can help differentiate between the two diseases. Two cases originally diagnosed as LPHL were re-assigned the diagnosis of THRLBCL.

Gray zones around diffuse large B cell lymphoma. Conclusions based on the workshop of the XIV meeting of the European Association for Hematopathology and the Society of Hematopathology in Bordeaux, France

The term "gray-zone" lymphoma has been used to denote a group of lymphomas with overlapping histological, biological, and clinical features between various types of lymphomas. It has been used in the context of Hodgkin lymphomas (HL) and non-Hodgkin lymphomas (NHL), including classical HL (CHL), and primary mediastinal large B cell lymphoma, cases with overlapping features between nodular lymphocyte predominant Hodgkin lymphoma and T-cell/histiocyte-rich large B cell lymphoma, CHL, and Epstein-Barr-virus-positive lymphoproliferative disorders, and peripheral T cell lymphomas simulating CHL. A second group of gray-zone lymphomas includes B cell NHL with intermediate features between diffuse large B cell lymphoma and classical Burkitt lymphoma. In order to review controversial issues in gray-zone lymphomas, a joint Workshop of the European Association for Hematopathology and the Society for Hematopathology was held in Bordeaux, France, in September 2008. The panel members reviewed and discussed 145 submitted cases and reached consensus diagnoses. This Workshop summary is focused on the most controversial aspects of gray-zone lymphomas and describes the panel's proposals regarding diagnostic criteria, terminology, and new prognostic and diagnostic parameters.

Histiocytic and t-cell rich b-cell lymphoma (TCRBCL) of the stomach

Although stomach is a frequent site of extranodal lymphomas, histiocyte-rich TCRBCL has not yet been described there. Even histology of repeated gastrobiopsies of this uncommon, diffuse, large B-cell lymphoma may be inconclusive and partial gastrectomy cannot be avoided. It is only immunohistology (CD20, CD43, CD68) of the paraffin blocks from the resection specimen that can lead to the final diagnosis of intermediate grade malignant lymphoma.

Rituximab in relapsed lymphocyte-predominant Hodgkin lymphoma: long-term results of a phase 2 trial by the German Hodgkin Lymphoma Study Group (GHSG)

Because nodular lymphocyte-predominant Hodgkin lymphoma (NLPHL) express CD20, rituximab may be used as a nonmutagenic treatment option to avoid late toxicities in this rather indolent entity. Between 1999 and 2004, the German Hodgkin Study Group (GHSG) investigated the activity of rituximab (375 mg/m(2) in 4 doses) in a phase 2 trial in 21 relapsed or refractory NLPHL patients. The initial diagnosis of NLPHL was confirmed in 15 of the 21 enrolled patients by reference pathology. The remaining cases were reclassified as Hodgkin lymphoma transformed to T-cell rich B-cell lymphoma (TCRBCL; n = 2) or CD20(+) classical Hodgkin lymphoma (cHL; n = 4). In NLPHL patients the overall response rate was 94%, including 8 complete remission (CR) and 6 partial remission (PR). With a median follow-up of 63 months (range, 3-84), the median time to progression was 33 months, with the median overall survival (OS) not reached. Thus, rituximab is highly effective in relapsed and refractory NLPHL. This study is registered at http://www.klinisches-studienzentrum.de/trial/285.

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/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.

Proliferation rate and outcome in children with T-cell rich B-cell lymphoma: a clinicopathologic study from the NHL-BFM-study group

T-cell rich B-cell lymphoma (TCRBCL) is considered a rare variant of aggressive B-cell lymphoma characterized by few neoplastic cells and a large reactive infiltrate with striking similarities to nodular lymphocyte predominant Hodgkin's lymphoma (NLPHL). In childhood, these tumors occur even less frequently. Biopsy specimens at diagnosis from 16 children (13 boys) with a median age of 12 years (range, 7 to 18) were immunophenotyped. The proliferation rate was assessed with monoclonal antibodies against Ki-67 and repp86 antigens and additional clonality analyses were performed. Ten patients had localized disease and only two had B symptoms. All patients showed high Ki-67 expression (median: 80%, range 40% to 90%), but low repp86 expression (median: 25%, range 10% to 50%). PCR-based clonality studies of the hypervariable CDR III region of the immunoglobuline heavy chain and the T-cell receptor gamma-chain genes demonstrated predominant clones in nine and five patients, respectively. Three patients had previous or concomitant NLPHL and two of them received initial treatment for Hodgkin's disease. All patients achieved remission after a brief polychemotherapy regimen. Two patients subsequently relapsed and one was rescued by salvage therapy including autologous stem cell transplantation. At a median follow-up of 23 months, 15 patients (94%) are alive. The striking contrast between the proliferation rates determined by Ki-67 and repp86 expression points to a possible arrest in the G1 cell cycle phase because repp86 expression is restricted to the S, G2 and M cell cycle phases. This G1 arrest may explain the paradoxon of high Ki-67 expression in a paucicellular lymphoma with a favorable prognosis in young patients.

Pediatric EBV-positive T-cell/histiocyte-rich large B-cell lymphoma with clonal cells in the bone marrow without overt involvement

T-cell/histiocyte-rich large B-cell lymphoma (TCHRLBCL) is a variant of large B-cell lymphoma only rarely encountered in children. Here we report the case of an 8-year-old African American boy with Epstein-Barr virus (EBV)-positive TCHRLBCL who initially presented with right submandibular, anterior cervical and supraclavicular lymphadenopathy. Cytogenetic analysis of the lymph node revealed a near-triploid karyotype with complex chromosomal aberrations. Although morphologically the bone marrow was normal, the same cytogenetically abnormal clone was detected. The patient responded to chemotherapy with CHOP (doxorubicin, cyclophosphamide, vincristine and prednisone) therapy, with disappearance of the abnormal clone from the bone marrow. The patient remains in remission 26 months after the initial diagnosis.

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.

Applications of Flow Cytometry and Immunohistochemistry to Diagnostic Hematopathology

Objective.—Diagnostic hematopathology depends on the applications of flow cytometric immunophenotyping and immunohistochemical immunophenotyping combined with the cytomorphology and histologic features of each case. Select cases may require additional ancillary cytogenetic and molecular studies for diagnosis. The purpose of this review is to focus on the applications of flow cytometric and immunohistochemical immunophenotyping of paraffin-embedded tissue to diagnostic hematopathology. Advantages and disadvantages of these techniques are examined.

Data Sources.—The literature is extensively reviewed (PubMed 1985–2003) with an emphasis on the most recent applications and those that are most useful clinically, both diagnostically and prognostically.

Study Selection.—Studies were selected based on statistically significant results in large studies with reported adequate clinical follow-up.

Data Extraction.—The methodology was reviewed in the selected studies to ensure reliable comparison of reported data.

Data Synthesis.—Flow cytometric immunophenotyping offers the sensitive detection of antigens for which antibodies may not be available for paraffin immunohistochemical immunophenotyping. However, paraffin immunohistochemical immunophenotyping offers preservation of architecture and evaluation of expression of some proteins, which may not be available by flow cytometric immunophenotyping. These techniques should be used as complimentary tools in diagnostic hematopathology.

Conclusions.—There are extensive applications of flow cytometric and immunohistochemical immunophenotyping to diagnostic hematopathology. As cytogenetic and molecular findings evolve in diagnostic hematopathology, there may be additional applications of flow cytometric and immunohistochemical immunophenotyping to this field of pathology.

Immunophenotypic and molecular studies in the diagnosis and classification of malignant lymphoma

Immunophenotypic and molecular studies play an increasingly important role in the diagnosis and classification of lymphoid neoplasms. These studies are not yet a substitute for expert histopathologic evaluation, but are a valuable adjunct to the examination of the hematoxylin and eosin-stained slide. Major applications include determination of lineage, determination of B and T cell monoclonality, detection of oncoprotein expression, and detection of oncogene rearrangements and chromosomal translocations. The recognition of the lymphomas as distinct biologic entities with specific immunophenotypic and genotypic features, as embodied in the Revised European-American Lymphoma (REAL) and World Health Organization (WHO) classifications, is a key to the future development and application of targeted biologic and molecular therapies. In the future, application of gene expression array analysis to the lymphoid neoplasms will permit classification of the lymphomas at a molecular level.

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.

Characterization of variant patterns of nodular lymphocyte predominant hodgkin lymphoma with immunohistologic and clinical correlation

Nodular lymphocyte predominant Hodgkin lymphoma (NLPHL) has traditionally been recognized as having two morphologic patterns, nodular and diffuse, and the current WHO definition of NLPHL requires at least a partial nodular pattern. Variant patterns have not been well documented. We analyzed retrospectively the morphologic and immunophenotypic patterns of NLPHL from 118 patients (total of 137 biopsy samples). Histology plus antibodies directed against CD20, CD3, and CD21 were used to evaluate the immunoarchitecture. We identified six distinct immunoarchitectural patterns in our cases of NLPHL: "classic" (B-cell-rich) nodular, serpiginous/interconnected nodular, nodular with prominent extranodular L&H cells, T-cell-rich nodular, diffuse with a T-cell-rich background (T-cell-rich B-cell lymphoma [TCRBCL]-like), and a (diffuse) B-cell-rich pattern. Small germinal centers within neoplastic nodules were found in approximately 15% of cases, a finding not previously emphasized in NLPHL. Prominent sclerosis was identified in approximately 20% of cases and was frequently seen in recurrent disease. Clinical follow-up was obtained on 56 patients, including 26 patients who had not had recurrence of disease and 30 patients who had recurrence. The follow-up period was 5 months to 16 years (median 2.5 years). The presence of a diffuse (TCRBCL-like) pattern was significantly more common in patients with recurrent disease than those without recurrence. Furthermore, the presence of a diffuse pattern (TCRBCL-like) was shown to be an independent predictor of recurrent disease (P = 0.00324). In addition, there is a tendency for progression to an increasingly more diffuse pattern over time. Analysis of sequential biopsies from patients with recurrent disease suggests that the presence of prominent extranodular L&H cells might represent early evolution to a diffuse (TCRBCL-like) pattern. We also report three patients who presented initially with diffuse large B-cell lymphoma and later developed NLPHL.

Micronodular T-cell/histiocyte-rich large B-cell lymphoma of the spleen: histology, immunophenotype, and differential diagnosis

Occasionally, primary large B-cell lymphomas (LBLs) arising in the spleen present with a micronodular pattern involving the splenic white pulp but sparing the red pulp. Histologically, the nodules contain scattered large B cells in a background of numerous T cells and histiocytes. They can cause substantial difficulty in histologic diagnosis as the morphology can mimic reactive and inflammatory lesions as well as other lymphoid neoplasms. In this study, we examined the histology and immunophenotype of the micronodular T-cell/histiocyte-rich LBL (MTLBL) of the spleen with a view to establish the characteristics that may be helpful in diagnosis. Paraffin-embedded material from 17 cases of MTLBL was studied. Clinical features and histology were reviewed and immunohistochemistry was performed for immunoglobulins, CD20, CD79a, CD3, CD68, CD10, BCL6, BCL2, OCT-2, epithelial membrane antigen, CD30, CD138, and EBV markers. The median age of presentation was 56 years, and the most frequent presenting features were anemia and B symptoms. All cases showed a micronodular pattern of involvement. The tumor nodules comprised a mixture of numerous CD3+ T cells and CD68+ histiocytes and scattered large CD20+ B cells with immunoglobulin light chain restriction. They were positive for BCL6 and OCT2 but negative for CD10, CD138, and EBV markers. There was variable expression of epithelial membrane antigen, Bcl-2, and CD30. No follicle dendritic cell meshwork infrastructure underlying the nodules could be demonstrated by staining for CD21 or CD35 antigens. The prognosis was poor; seven of the 12 cases with follow-up were dead within 2 years. MTLBL is unique variant of T-cell/histiocyte-rich diffuse LBL, characterized by primary splenic presentation and a micronodular architecture. The main differential diagnoses include granulomatous inflammation, Hodgkin's lymphoma, follicular lymphoma, and peripheral T-cell lymphomas.

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 - 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.

Hodgkin's lymphoma: the pathologist's viewpoint

Despite its well known histological and clinical features, Hodgkin's lymphoma (HL) has recently been the object of intense research activity, leading to a better understanding of its phenotype, molecular characteristics, histogenesis, and possible mechanisms of lymphomagenesis. There is complete consensus on the B cell derivation of the tumour in most cases, and on the relevance of Epstein-Barr virus infection and defective cytokinesis in at least a proportion of patients. The REAL/WHO classification recognises a basic distinction between lymphocyte predominance HL (LP-HL) and classic HL (CHL), reflecting the differences in clinical presentation and behaviour, morphology, phenotype, and molecular features. CHL has been classified into four subtypes: lymphocyte rich, nodular sclerosing, with mixed cellularity, and lymphocyte depleted. The borders between CHL and anaplastic large cell lymphoma have become sharper, whereas those between LP-HL and T cell rich B cell lymphoma remain ill defined. Treatments adjusted to the pathobiological characteristics of the tumour in at risk patients have been proposed and are on the way to being applied.

T-cell-rich B-cell lymphoma. Analysis of clinical features, response to treatment, survival and comparison with diffuse large B-cell lymphoma

OBJECTIVES

Clinical features, response to treatment and survival of T-cell-rich B-cell lymphoma (TCRBCL) patients were compared to those of a similar group of patients with diffuse large B-cell lymphoma (DLBCL).

METHODS

Between 1992 and 1999, 10 patients with a diagnosis of TCRBCL were treated in our department. Over the same 7-year period, a group of 65 patients with DLBCL were diagnosed in the same department. Both groups of patients were treated with the same anthracycline-based chemotherapy.

RESULTS

A significantly higher percentage of patients with TCRBCL presented with B-symptoms, elevated LDH, bone marrow infiltration and disseminated extranodal involvement compared to patients with DLBCL. TCRBCL patients responded poorly to combination chemotherapy, since only 3 of them achieved complete remission (33%) compared to 48 (75%) patients with DLBCL. All patients with TCRBCL who achieved complete response relapsed within the first 2 years while 65% of patients with DLBCL survive disease free for a median follow-up period of 4 years. The median overall survival for DLBCL patients has not been reached yet, while it was 18 months for TCRBCL patients.

CONCLUSIONS

Although the number of patients in our study is small, it seems that patients with TCRBCL present with advanced disease, respond poorly to chemotherapy and display a short disease-free and overall survival compared to patients with DLBCL.

Immunoglobulin and T-cell receptor gene-gene rearrangement in pleural cavity-based T-cell rich B-cell lymphoma in an immunocompetent patient

Body cavity-based lymphomas are fluid-based lymphomas that are not associated with a tumor mass or adenopathy which could explain the origin of the lymphomatous effusion. A distinct lymphoma that grows in the body cavity as a lymphomatous effusion in the absence of a tumor mass has been identified as a primary effusion lymphoma. This almost exclusively occurs in patients with acquired immunodeficiency syndrome (AIDS), who invariably have a history of Kaposi sarcoma. We report a rare case of a recurrent pleural effusion in an immunocompetent patient. There was no evidence of lymphadenopathy or an associated mass on computerized tomography of the chest, abdomen and pelvis. Serology for HIV, HHS-8, EBV and HTLV-1 were negative. Cytologic examination of the pleural fluid showed an elevated white cell count with 97% lymphocytes, mostly with T-cell markers. Bone marrow aspirate and biopsy were negative and bronchoscopy was unrevealing. Pleural biopsy was significant for >70% T-lymphocytes and some large atypical cells. Which had CD19, CD20 and weak bcl-2 positivity. Kappa and lambda light chains did not show distinct clonality. A preliminary diagnosis of T-cell rich B-cell lymphoma (TCRBCL) of the pleural cavity was made. The diagnosis was confirmed with DNA studies done on the pleural biopsy specimen using PCR and southern blot. Dual rearrangement of Ig heavy chain region and TCR-beta genes were identified. The patient responded to combination chemotherapy with cyclophosphamide, adriamycin, vincristine and prednisone. Our case is the first known case of pleural cavity-based TCRBCL and illustrates the role of gene rearrangement studies in such patients.

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.

Utility of flow cytometry immunophenotyping for the diagnosis and classification of lymphoma in community hospital clinical needle aspiration/biopsies

CONTEXT

Flow cytometry immunophenotyping (FC) of needle aspiration/biopsy (NAB) samples has been reported to be useful for the diagnosis and classification of lymphoma in university and cancer center-based settings. Nevertheless, there is no agreement on the utility of these methods.

OBJECTIVE

To further define the utility of adjunctive FC of clinical NAB for the diagnosis and classification of lymphoma, and to determine if this approach is practicable in a routine clinical practice setting.

SETTING

A community-based hospital.

METHODS

Clinical NABs were submitted for adjunctive FC between June 1996 and September 1999 if initial smears were suspicious for lymphoma. Smears and cell block or needle core tissues were routinely processed and paraffin-section immunostains were performed if indicated. The final diagnosis was determined by correlating clinical and pathologic data, and the revised European-American classification criteria were used to subtype lymphomas.

RESULTS

Needle aspiration/biopsies from 60 different patients were submitted for FC. Final diagnoses were lymphoma (n = 38), other neoplasm (n = 15), benign (n = 6), or insufficient (n = 1). For 38 lymphomas (20 primary, 18 recurrent), patients ranged in age from 32 to 86 years (mean, 62 years); samples were obtained from the retroperitoneum (n = 11), lymph node (n = 9), abdomen (n = 8), mediastinum (n = 6), or other site (n = 4); and lymphoma subtypes were indolent B-cell (n = 20; 2 small lymphocytic, 14 follicle center, 4 not subtyped), aggressive B-cell (n = 14; 3 mantle cell, 10 large cell, 1 not subtyped), B-cell not further specified (n = 2), or Hodgkin disease (n = 2). For the diagnosis of these lymphomas, FC was necessary in 20 cases, useful in 14 cases, not useful in 2 cases, and misleading in 2 cases. Thirty-two of 36 lymphoma patients with follow-up data received antitumor therapy based on the results of NAB plus FC.

CONCLUSIONS

Adjunctive FC of NABs is potentially practicable in a community hospital, is necessary or useful for the diagnosis and subtyping of most B-cell lymphomas, and can help direct lymphoma therapy. Repeated NAB or surgical biopsy is necessary for diagnosis or treatment in some cases.

Primary T-cell-rich B-cell lymphoma of the ethmoid sinus. A case report with 5 years of follow-up

T-cell-rich B-cell lymphoma (TCRBCL) is an uncommon and recently recognized variant of B-cell non-Hodgkin lymphoma characterized by a few large neoplastic B cells amid a predominant population of reactive T lymphocytes and variable numbers of histiocytes. Morphologically, TCRBCL resembles a variety of non-Hodgkin lymphomas and Hodgkin disease. Accurate diagnosis and proper treatment are essential to assure a favorable prognosis. To our knowledge, this is the first report of ethmoid sinus presentation of TCRBCL in an Epstein-Barr virus-negative 51-year-old man. Combined chemotherapy and radiotherapy were administered based on the correct diagnosis. The patient has had a complete response with no recurrence during the 5-year follow-up.

Lymphocyte predominance Hodgkin's disease: the use of bcl-6 and CD57 in diagnosis and differential diagnosis

Distinction of lymphocyte predominance Hodgkin's disease (LPHD) from other forms of lymphoma often requires immunohistochemistry (IHC). Most previously published recommended panels include markers to define the large neoplastic cells (for example, CD20, J chain, CD45) as well as the non-neoplastic background cells (CD21, CD45RO, CD57, TiA 1). In the present study we examine the practical use of a double IHC method designed to look simultaneously at two germinal center specific cell types: bcl6+ cells and [bc16+, CD57+] co-positive cells. All 10 nodular LPHD had bcl6+ large cells and numerous CD57+ small background cells, including [bcl6+CD57+] cells in rosettes. One case of LPHD with large cell transformation contained numerous bcl6+ large cells both singly (in areas of typical LPHD) and in sheets (in foci of large cell transformation), many CD57+ small cells but few [bcl6+CD57+] co-positive cells and no rosettes. In none of the five cases of florid progressive transformation of germinal centers were true rosettes seen, although all contained variable numbers of bcl6+ large cells and CD57+ cells. Lymphocyte-rich classic Hodgkin's disease LRCHD cases were notable for bcl6 reactivity in Reed-Sternberg cells in all cases, numerous background small bcl6+ lymphocytes, and rare CD57+ cells. Two phenotypic profiles were associated with the 10 cases of T cell-rich B cell large cell lymphoma (TCRBCL). In the first, group "A," six of six cases had bc16- large cells and few CD57+ small cells, and none had significant numbers of [bcl6+, CD57+] co-positive cells. In the second, group "B," four of four cases had bcl6+ large cells with numerous CD57+ and [bcl6+, CD57+] co-positive cells. These findings not only show that LPHD can be distinguished from its morphologic mimics through identification of specific germinal center cell types, but also identifies a second group of TCRBCL (group "B") whose phenotype suggests it might be an architectural variant of nodular LPHD.

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.

The use of flow cytometry in the diagnosis and monitoring of malignant hematological disorders

Flow cytometry is a modality with ever increasing application in modern hematological practice. This is due to the rapidity of obtaining results, ease of use and increasing power to detect abnormal populations of cells. The major uses of flow cytometry in malignant hematology are in the diagnosis, classification and monitoring of diseases such as leukemia, lymphoma and myeloma. The technique is now used also to detect disease-specific populations of cells in paroxysmal nocturnal hemoglobinuria. This review describes the use of flow cytometry in many disease states.

Value and limitations of fine-needle aspiration cytology in diagnosis and classification of lymphomas: A review

The fine needle aspiration (FNA) cytologic diagnosis of non-Hodgkin's lymphoma (NHL) depends upon finding a relatively monotonous population of lymphoid cells in smears. Lymphomas have successfully been classified by FNA cytology following the prevalent histologic classifications. The success rate of FNA cytology ranges from 80%-90% in diagnosis of NHL and from 67.5%-86% in its subtyping. The cytodiagnosis of Hodgkin's disease (HD) depends upon demonstration of Reed-Sternberg cells or Hodgkin's cells amongst appropriate reactive cell components. The diagnostic accuracy of FNA cytology for HD has also been invariably high (>85%). Yet, the role of cytology in primary diagnosis, subclassification and management of patients with lymphoma remains controversial. The differential diagnostic problems for NHL include a group of small round cell tumors, nonlymphoid acute leukemias and HD. Reservations have been expressed regarding the efficacy of cytology in separating florid reactive hyperplasia from low-grade malignant lymphoma. The reported cytodiagnostic accuracy for follicular lymphomas and nodular sclerosis type of HD is less compared to other subtypes of NHL and HD respectively since nodular pattern and sclerosis are strict histologic criteria which can not be appreciated in cytologic preparations. Entities like atypical lymphoproliferative disorders, peripheral T-cell lymphomas and Ki-1 positive anaplastic large cell lymphomas pose diagnostic challenges to cytologists. Despite these limitations, FNA cytology remains the first line of investigations (screening test) used in cases of lymphadenopathy. Besides initial diagnosis of lymphoma, it helps in detection of residual disease, recurrences and progression of low-grade to high-grade lymphoma, and helps in staging the disease. Availability of prior FNA cytology report facilitates the histologic diagnosis and classification of NHL. Various special ancillary techniques are now being performed on lymph node aspirates to diagnose lymphoma versus other malignancies, and to decide the functional character of lymphomas and their clonal nature. Diagn. Cytopathol. 1999;21:240-249.

Molecular Analysis of Single B Cells From T-Cell–Rich B-Cell Lymphoma Shows the Derivation of the Tumor Cells From Mutating Germinal Center B Cells and Exemplifies Means by Which Immunoglobulin Genes Are Modified in Germinal Center B Cells

T-cell–rich B-cell lymphoma (TCRBCL) belongs to the group of diffuse large cell lymphomas (DLL). It is characterized by a small number of tumor B cells among a major population of nonmalignant polyclonal T cells. To identify the developmental stage of the tumor progenitor cells, we micromanipulated the putative neoplastic large CD20+ cells from TCRBCLs and amplified and sequenced immunoglobulin (Ig) V gene rearrangements from individual cells. In six cases, clonal Ig heavy, as well as light chain, gene rearrangements were amplified from the isolated B cells. All six cases harbored somatically mutated V gene rearrangements with an average mutation frequency of 15.5% for heavy (VH) and 5.9% for light (VL) chains and intraclonal diversity based on somatic mutation. These findings identify germinal center (GC) B cells as the precursors of the transformed B cells in TCRBCL. The study also exemplifies various means how Ig gene rearrangements can be modified by GC B cells or their malignant counterparts in TCRBCL: In one case, the tumor precursor may have switched from κ to λ light chain expression after acquiring a crippling mutation within the initially functional κ light chain gene. In another case, the tumor cells harbor two in-frame VH gene rearrangements, one of which was rendered nonfunctional by somatic mutation. Either the tumor cell precursor entered the GC with two potentially functional in-frame rearrangements or the second VHDHJHrearrangement occurred in the GC after the initial in-frame rearrangement was inactivated by somatic mutation. Finally, in each of the six cases, at least one cell contained two (or more) copies of a clonal Ig gene rearrangement with sequence variations between these copies. The presence of sequence variants for V region genes within single B cells has so far not been observed in any other normal or transformed B lymphocyte. Fluorescence in situ hybridization (FISH) points to a generalized polyploidy of the tumor cells.

Molecular Analysis of Single B Cells From T-Cell–Rich B-Cell Lymphoma Shows the Derivation of the Tumor Cells From Mutating Germinal Center B Cells and Exemplifies Means by Which Immunoglobulin Genes Are Modified in Germinal Center B Cells

T-cell–rich B-cell lymphoma (TCRBCL) belongs to the group of diffuse large cell lymphomas (DLL). It is characterized by a small number of tumor B cells among a major population of nonmalignant polyclonal T cells. To identify the developmental stage of the tumor progenitor cells, we micromanipulated the putative neoplastic large CD20+ cells from TCRBCLs and amplified and sequenced immunoglobulin (Ig) V gene rearrangements from individual cells. In six cases, clonal Ig heavy, as well as light chain, gene rearrangements were amplified from the isolated B cells. All six cases harbored somatically mutated V gene rearrangements with an average mutation frequency of 15.5% for heavy (VH) and 5.9% for light (VL) chains and intraclonal diversity based on somatic mutation. These findings identify germinal center (GC) B cells as the precursors of the transformed B cells in TCRBCL. The study also exemplifies various means how Ig gene rearrangements can be modified by GC B cells or their malignant counterparts in TCRBCL: In one case, the tumor precursor may have switched from κ to λ light chain expression after acquiring a crippling mutation within the initially functional κ light chain gene. In another case, the tumor cells harbor two in-frame VH gene rearrangements, one of which was rendered nonfunctional by somatic mutation. Either the tumor cell precursor entered the GC with two potentially functional in-frame rearrangements or the second VHDHJHrearrangement occurred in the GC after the initial in-frame rearrangement was inactivated by somatic mutation. Finally, in each of the six cases, at least one cell contained two (or more) copies of a clonal Ig gene rearrangement with sequence variations between these copies. The presence of sequence variants for V region genes within single B cells has so far not been observed in any other normal or transformed B lymphocyte. Fluorescence in situ hybridization (FISH) points to a generalized polyploidy of the tumor cells.

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 B-cell lymphoma: fine-needle aspiration cytology and immunocytochemistry

Cytomorphologic and immunocytochemical characteristics of FNA aspirates from 5 patients with T-cell-rich B-cell lymphoma are described. The aspirates were dominated (over 90%) by small mature lymphocytes, but there was a sparse admixture of large, immature lymphoid cells, some of which mimicked Hodgkin's or Reed Sternberg's cells. The cytologic picture of 3 cases was similar to that of Hodgkin's disease of lymphocytic predominance. Two cases presented, in addition to the components described above, fragments of small vessels and epithelioid cells, which raised the possibility of true T-cell lymphoma. Immunocytochemical analysis of cytospin preparations showed that the mature small lymphocytes were of T-phenotype, while the large cells were of B-phenotype. Light-chain restriction was demonstrated in all cases, and monoclonality for kappa and lambda was shown in 4 cases and 1 case, respectively. Three cases had a previous histological diagnosis of Hodgkin's disease, which was revised to T-cell-rich B-cell lymphoma as a consequence of the cytologic and immunologic findings in aspirates from recurrent/remaining lymphoma manifestations. It can thus be concluded that immunocytochemistry in conjunction with cytomorphology on fine-needle aspirates will allow a conclusive diagnosis of T-cell-rich B-cell lymphoma and its differentiation from Hodgkin's disease and T-cell lymphomas. This distinction, from a prognostic and therapeutic standpoint, is of utmost importance.

Molecular pathology in the diagnosis of hematologic neoplasia. Review article

Over the past decade molecular genetic methods have played an increasingly important role in the diagnosis of hematologic malignancies. Moreover, they have provided a tool to analyze many of the non-random cytogenetic anomalies associated with hematologic neoplasias, contributing considerably to our understanding of several of those diseases, and to improving diagnostic accuracy. The rapid development of molecular genetics progressively allows the replacement of time-consuming and technically demanding procedures. Even more relevant are the new clinical applications that already include the search for valuable prognostic information and ways of evaluating minimal residual disease or recognizing early relapsing disease. This paper is a critical but necessarily simplified overview of the main contributions of molecular genetics to the field of hematopathology. We discuss the information provided by several molecular methods within different clinical contexts, covering common problems in diagnostic pathology as well as prognostic evaluation and therapy monitoring.

Mistaken diagnoses of Hodgkin's disease

This article reviews the frequency of and general types of diagnostic errors in Hodgkin's disease (HD) over the past several decades, discusses the most common diagnostic errors in the four histologic subtypes of HD today, and describes some of the clinical and pathologic features that may aid in avoiding a mistaken diagnosis of HD.

The malignant lymphomas of Kenya: morphology, immunophenotype, and frequency of Epstein-Barr virus in 73 cases

Recent information is limited regarding pathological features of the malignant lymphomas of Africa, other than Burkitt's lymphoma. In this study, we apply modern techniques and nomenclature to classify 73 lymphomas from a central histopathology laboratory serving 40 mission hospitals in Kenya. We were particularly interested in the frequency of recently recognized lymphomas and the incidence of Epstein-Barr virus in various lymphoma subtypes. Malignant lymphomas accounted for 12% of all surgical pathology specimens processed in the laboratory over the 21-month period included in the study. Patient age ranged from 4 to 97 years (median, 35 years). The male-to-female ratio was 2.5:1. Sixty lymphomas (82%) were non-Hodgkin's, and 13 (18%) were Hodgkin's disease. Of the non-Hodgkin's lymphomas (NHLs), 52 (87%) were B-lineage, including 21 (35% of NHLs) Burkitt's lymphomas (only one from the jaw), 11 (18%) diffuse large B cell lymphomas; nine (15%) small lymphocytic lymphomas, six (10%) Burkitt's-like lymphomas, two (3%) follicular lymphomas (two of two expressed bcl-2 protein; one of two showed bcl-2 major breakpoint region rearrangement), two (3%) mantle cell lymphomas, and one extranodal marginal zone lymphoma. Of the eight T cell lymphomas, six were precursor T-cell type, and the remaining two were peripheral T cell lymphomas, unspecified. The median age of the 13 patients (18% of lymphomas) with Hodgkin's disease was 23 years (range, 9 to 97 years). Six were nodular sclerosis, four were mixed cellularity, one case each was lymphocyte depletion, lymphocyte predominance, and unclassified Hodgkin's disease. Hodgkin's cells in 6 of the 12 nonlymphocyte predominance cases were positive for CD20, and in three of the six for CD45 as well. Epstein-Barr virus was identified using in situ hybridization for EBER 1 in the malignant cells of 22 of 39 informative lymphomas, including each of 17 Burkitt's lymphomas, and three of seven diffuse large B cell lymphomas. Of note, none of five Burkitt's-like lymphomas expressed EBER 1. One of two informative cases of peripheral T cell lymphoma, and four of nine cases of Hodgkin's disease were EBER 1 positive. In summary, T cell lymphomas and recently recognized B-lineage non-Hodgkin's lymphoma subtypes do not appear to be particularly common in East Africa.