T-cell-rich B-cell lymphomas. A clinicopathologic study of 19 cases.

T-cell-rich B-cell lymphomas (TCRBCLs) are recently described, unusual non-Hodgkin's lymphomas that have a diffuse morphology, a predominance of reactive T-cells, and a minority of neoplastic B-cells. The clinical and pathological features of 19 TCRBCLs, all of which demonstrated B-cell clonality, are presented. These lymphomas generally affected older patients by widespread disease and usually were nodal in origin. Treatment varied, but continuous complete remissions (eight patients) were achieved only in those receiving chemotherapy directed at intermediate-grade lymphomas. Although morphologically heterogeneous, all cases resembled peripheral T-cell lymphomas (PTCLs); several TCRBCLs also contained Reed-Sternberg-like cells. Flow cytometry or frozen-section immunoperoxidase failed to detect monotypic immunoglobulin (Ig) in eight of eight cases tested. In contrast, paraffin immunoperoxidase was very useful diagnostically, showing large L26 (CD20-associated) positive cells scattered singly or in small clusters among numerous small T-cells (UCHL1[CD45RO] positive) in all cases. Monotypic cytoplasmic Ig was present in 16 of 19 cases, one of which exhibited plasmacytic differentiation. Southern blot analysis demonstrated relatively faint Ig JH and/or JK bands, indicating a small monoclonal B-cell population in nine of 11 cases, one of which also showed a bcl-2 rearrangement. No T-cell receptor gene rearrangements were observed. These results showed that TCRBCLs may be easily confused with PTCLs or occasionally confused with Hodgkin's disease. TCRBCLs are probably heterogeneous biologically; some cases are of follicular center cell origin. These lymphomas respond to chemotherapy directed at intermediate-grade lymphomas, apparently have a better prognosis than PTCLs, and seem to represent morphological variants of different types of large B-cell lymphomas.     

The value of immunophenotyping on paraffin sections in the identification of T-cell rich B-cell large-cell lymphomas: lineage confirmed by JH rearrangement

Immunophenotyping of lymphomas using paraffin-embedded lymphoid tissue, not previously distorted by frozen section, is useful in identifying the large neoplastic B cells that may be in the minority in T-cell rich B-cell lymphoma (TCRBCL). Even in cases in which frozen tissue sections are available, the improved morphology in unfrozen sections allows the proper classification of these lymphomas as large cell and identifies their B-cell lineage, which is important for clinical therapeutic studies. Seven cases initially believed to be diffuse mixed cell lymphoma of possible peripheral T-cell lineage showed the large cells to be immunoreactive with L-26 (pan B-cell marker) with the majority of smaller lymphocytes immunoreactive for UCHL-1 and Leu-22 (pan T-cell markers). K/lambda immunostaining on frozen sections was equivocal. In these cases, the diagnosis of large-cell lymphoma of B-cell lineage was confirmed by detection of immunoglobulin heavy- (all seven cases) and light- (six of seven cases) chain gene rearrangements, with germ-line configuration of the T-cell receptor beta-chain gene (all cases). Some cases of TCRBCL may not show detectable rearrangement of the immunoglobulin genes because of the low concentration of neoplastic cells in the samples submitted. The presence of rearrangements in these seven cases, however, supports the diagnosis of TCRBCL based on paraffin immunophenotyping when frozen tissue is not available or when molecular studies are not feasible. Although these seven cases are classified as large-cell lymphoma, an intermediate-grade lymphoma, the influence of the reactive T-cell population on the clinical behavior will require follow-up studies.     

Epstein-Barr virus negative clonal plasma cell proliferations and lymphomas in peripheral T-cell lymphomas: a phenomenon with distinctive clinicopathologic features

Clonal B-cell populations have been described in peripheral T-cell lymphomas (PTCL) as secondary Epstein-Barr virus (EBV) driven B-cell expansions that may evolve to an overt B-cell lymphoma. EBV-negative B-cell proliferations associated with T-cell lymphomas are uncommon and not well characterized. We studied 15 patients who developed an EBV-negative B-cell proliferation or malignant lymphoma associated with PTCL. The T-cell tumors were 8 PTCL, not otherwise specified, 4 angioimmunoblastic T-cell lymphomas, and 3 cutaneous PTCL. The B-cell component was intermingled with the PTCL in all patients and it was classified as clonal/monotypic plasma cell proliferation in 8 lesions, clonal/monotypic large B-cell proliferation in 4 patients, and B-cell lymphoma with plasmacytic/plasmablastic differentiation in 3 patients. Two patients had 2 clonally unrelated plasma cell proliferations associated with the same PTCL. All cases showed cytoplasmic Ig light chain restriction. Clonal IgH and T-cell receptor rearrangements were detected in 11/12 and 11/13 cases examined, respectively. EBV, cytomegalovirus, and HHV-8 were not observed in any of the examined cases. Sequential samples in 7 patients showed persistence of the PTCL and the B-cell component in 4, the PTCL without the B-cell lymphoma in 2, and progression of the B-cell neoplasm in 1. Patients followed an aggressive clinical course similar to conventional PTCL. In conclusion, EBV-negative clonal or mononotypic B-cell proliferations in patients with PTCL present with a spectrum of lesions ranging from plasma cell proliferations to overt lymphomas with plasmacytic/plasmablastic features. The distinctive features of these patients suggest that these lesions represent a specific phenomenon in PTCL.     

小肠原发性非霍奇金淋巴瘤34例临床分析

目的探讨小肠淋巴瘤的临床特点、治疗和预后。方法对1996年1月至2005年12月间收治的经组织病理学明确诊断、并作免疫学分型的原发性小肠淋巴瘤34例患者的临床资料进行分析。结果27例为B细胞淋巴瘤，7例为T细胞淋巴瘤。腹痛和肠梗阻是主要临床表现。用Ann Arbor分期，22例为Ⅰ～Ⅱ期，其中B细胞淋巴瘤20例（74．1％），T细胞淋巴瘤2例（2／7）；12例为Ⅲ～Ⅳ期，其中B细胞淋巴瘤7例（25．9％），T细胞淋巴瘤5例（5／7）；小肠B细胞淋巴瘤的分期低于T细胞淋巴瘤（P〈0．05）；27例行手术治疗，14例行6次化疗[方案为CHOP（环磷酰胺、阿霉素、长春新碱和强的松龙）]，8例同时加用抗CD20单克隆抗体Rituximab。T细胞淋巴瘤急诊手术率高于B细胞淋巴瘤（P〈0．05），B细胞淋巴瘤更易达到完全缓解（P〈0．05），累计生存率高于T细胞淋巴瘤（P〈0．05）。结论小肠B细胞淋巴瘤Ⅰ和Ⅱ期对手术和化疗效果佳，T细胞淋巴瘤的治疗效果和预后不满意。     

Histologic evolution of angioimmunoblastic T-cell lymphoma in consecutive biopsies: clinical correlation and insights into natural history and disease progression

Angioimmunoblastic T-cell lymphoma (AITL) is an uncommon, but aggressive nodal peripheral T-cell lymphoma. Little is known of its biology and its natural history has been poorly studied. We report the first comprehensive study on the natural history/histologic progression of AITL by reviewing consecutive biopsies in 31 cases. Immunostaining for CD3, CD20, CD10 and CD21, CD23, CNA-42, CD4, CD8, and Ki 67, in situ hybridization for Epstein-Barr virus (EBV)-encoded RNA and polymerase chain reaction for T-clonality and B-clonality were performed. Histologic progression from AITL with limited nodal involvement and hyperplastic follicles (pattern I) to typical AITL with or without regressed follicles (patterns II and III) was observed in 7 cases, one of which relapsed subsequently as pattern I. Thirteen cases showed typical AITL at presentation and follow-up. Eleven cases where polymerase chain reaction results for T-cell receptor-gamma gene rearrangement were directly compared showed an identical band-size in the initial and follow-up biopsies. Seven cases (23%) developed EBV-associated B-cell lymphomas [5 diffuse large B-cell lymphoma (DLBCL) and 2 classic Hodgkin lymphoma]. In 4 cases, a dominant B-cell clone was observed in biopsies lacking evidence of DLBCL. A single case was complicated by EBV-negative DLBCL, whereas another with large cell transformation had a T-cell phenotype. In conclusion, AITL represents a clonal T-cell proliferation with a stable T-cell clone throughout the disease. Partial nodal involvement with hyperplastic follicles is seen in early AITL and at relapse. When "morphologic high-grade transformation" occurs, it is usually due to a secondary (often EBV-associated) B-cell lymphoma, rather than a T-cell neoplasm.     

Ki-1 positive large cell lymphoma. A morphologic and immunologic study of 19 cases

In this report, we analyze the clinical, morphologic, and immunologic findings of 19 patients with Ki-1+ large cell lymphoma, a recently described malignant lymphoma which is usually of T-cell phenotype. Most patients in this selected series of 14 children and adolescents and five adults presented with peripheral lymphadenopathy or skin lesions. No patient had bone marrow involvement. Distinctive morphologic features of Ki-1+ large cell lymphoma are tumor cell pleomorphism, sinus infiltration, fibrosis, partial lymph node involvement, sparing of B-cell regions, and a prominent plasma cell infiltrate. Seventy-two percent of cases were of T-cell phenotype; the remaining cases expressed neither B- nor T-cell-specific markers. Virtually all cases were positive for Ia (HLA-DR), Tac (interleukin-2 receptor), and T9 (transferrin receptor), indicating that this lymphoma is frequently a tumor of activated T-cells. We conclude that a diagnosis of Ki-1+ large cell lymphoma should be considered in any pleomorphic tumor with the features described in this report.     

Clinical relevance of three subtypes of primary sinonasal lymphoma characterized by immunophenotypic analysis

BACKGROUND: The purpose of this study was to investigate the clinical relevance of subtypes categorized by immunophenotypic analysis in primary sinonasal lymphomas. METHODS: Eighty patients with localized non-Hodgkin's lymphoma involving the nasal cavity and/or paranasal sinuses were divided into three subtypes on the basis of their immunohistochemical findings: (A) B-cell lymphoma (n = 19), (B) T-cell lymphoma (n = 27), and (C) natural killer (NK)/T-cell lymphoma (n = 34). The clinicopathologic profiles, immunophenotypic data, patterns of treatment failure, and survival data among the three patient groups were retrospectively compared. RESULTS: The nasal cavity was the predominant site of involvement in T-cell and NK/T-cell lymphoma, whereas sinus involvement without nasal disease was common in B-cell lymphoma. Systemic B symptoms were frequently observed in NK/T-cell lymphoma. Almost all patients with NK/T-cell lymphoma showed a strong association with the Epstein-Barr virus by in situ hybridization studies. Sixty-five patients (81%) patients achieved complete remission after initial treatment, but 36 (55%) of these subsequently experienced treatment failure. Although there were no significant differences in locoregional failure rates among the patients of the three groups, distant failure was far more common in B-cell or NK/T-cell lymphoma than in T-cell lymphoma (p =.005). Most B-cell lymphoma cases showed a predilection for sites of systemic failure in the nodal and extranodal sites below the diaphragm, such as the paraaortic lymph nodes or the gastrointestinal (GI) tract, whereas patients with NK/T-cell lymphoma showed an increased risk of systemic dissemination to the skin, testes, or GI tract, including the development of hemophagocytic syndrome. The 5-year actuarial and disease-free survival rates for all patients were 57% and 51%, respectively. Of the three subtypes of primary sinonasal lymphomas, T-cell lymphoma seemed to carry the most favorable prognosis and NK/T-cell lymphoma the worst. (The 5-year actuarial survival rate was 57% for B-cell lymphoma, 80% for T-cell lymphoma, 37% for NK/T-cell lymphoma; p =.02, log-rank.) By univariate and multivariate analyses, immunophenotype was identified as the most important prognostic factor. CONCLUSIONS: Our data indicate that the three subtypes of primary sinonasal lymphomas classified by immunohistochemical studies exhibit different clinical profiles, different patterns of failure, and different treatment outcomes. Given these observations, it is concluded that the recognition of these distinct subsets, diagnosed on the basis of immunophenotypic study, is very important and clinically relevant in predicting their potential behavior and prognosis.     

B-cell capacity for expansion and differentiation into plasma cells are altered in osteoarthritis

ObjectiveAutoantibody (autoAbs) production in osteoarthritis (OA), coupled with evidence of disturbed B-cell homoeostasis, suggest a potential role for B-cells in OA. B-cells can differentiate with T-cell help (T-dep) or using alternative Toll like recptor (TLR) co-stimulation (TLR-dep). We analysed the capacity for differentiation of B-cells in OA versus age-matched healthy controls (HCs) and compared the capacity of OA synovitis-derived stromal cells to provide support for plasma cell (PC) maturation.MethodsB-cells were isolated from OA and HC. Standardised in vitro models of B-cell differentiation were used comparing T-dep (CD40 (cluster of differentiation-40/BCR (B-cell receptor)-ligation) versus TLR-dep (TLR7/BCR-activation). Differentiation marker expression was analysed by flow-cytometry; antibody secretion (immunnoglobulins IgM/IgA/IgG) by ELISA (enzyme-linked immunosorbent assay), gene expression by qPCR (quantitative polymerase chain reaction).ResultsCompared to HC, circulating OA B-cells showed an overall more mature phenotype. The gene expression profile of synovial OA B-cells resembled that of PCs. Circulating B-cells differentiated under both TLR-dep and T-dep, however OA B-cells executed differentiation faster in terms of change in surface marker and secreted more antibody at Day 6, while resulting in similar PC numbers at Day 13, with an altered phenotype at Day 13 in OA. The main difference was reduced early B-cells expansion in OA (notably in TLR-dep) and reduced cell death. Stromal cells support from OA-synovitis allowed better PC survival compared to bone marrow, with an additional population of cells and higher Ig-secretion.ConclusionOur findings suggest that OA B-cells present an altered capacity for proliferation and differentiation while remaining able to produce antibodies, notably in synovium. These findings may partly contribute to autoAbs development as recently observed in OA synovial fluids.     

Sinonasal lymphoma: a clinicopathologic analysis of 58 cases from the Massachusetts General Hospital.

Few large series compare lymphomas of the nasal cavity with those of the paranasal sinuses. We studied the cases of 58 patients, 34 males and 24 females, aged 7 to 92 years (mean, 57 years), who had lymphoma involving the nasal cavity or paranasal sinuses. Thirty-three patients had diffuse large B-cell lymphoma (DLBCL). Twenty-three were male and 10 were female, with an age range of 7 to 91 years (mean, 63 years); two were HIV-positive. Only 2 of 11 cases tested (one in an HIV-positive patient and one of lymphomatoid granulomatosis type) were Epstein-Barr virus (EBV)-positive. Thirty (91%) involved paranasal sinuses, 10 with nasal involvement, whereas three cases had nasal, but not sinus, involvement. At last follow-up, 16 (67%) were free of disease 7 to 169 months later (mean, 65 months), and 8 (33%) had died of disease 2 to 166 months later (mean, 45 months). Seventeen patients had nasal-type natural killer (NK)/T-cell lymphoma. There were 10 women and 7 men, aged 27 to 78 years (mean, 48 years). Thirteen of 14 were EBV-positive. Sixteen patients had nasal involvement, eight with sinus involvement. Eleven (73%) of 15 were alive and well 6 to 321 months later (mean, 139 months), three (20%) died of lymphoma 1, 11, and 12 months later, and one (7%) is alive with disease. There was one case each of marginal zone B-cell lymphoma, Burkitt's lymphoma, Burkitt-like lymphoma, peripheral T-cell lymphoma of unspecified type, and adult T-cell lymphoma/leukemia. In an additional three cases, the lymphomas were composed predominantly of large cells, but no immunophenotyping could be performed for subclassification. In 19 cases (17 DLBCLs, 1 Burkitt-like lymphoma, and 1 lymphoma of uncertain lineage), presenting symptoms included complaints related to the eyes. In 16 cases (13 DLBCLs, 1 Burkitt-like lymphoma, 1 nasal NK/T-cell lymphoma, and 1 lymphoma of uncertain lineage), the orbit was invaded by lymphoma. In our series, the most common lymphoma to arise in the sinonasal area is DLBCL, followed by nasal NK/T-cell lymphoma. Comparison of these two types of lymphoma showed that lymphomas involving sinuses without nasal involvement were predominantly DLBCLs (20 of 21), whereas nasal cavity lymphomas without sinus involvement were usually NK/T-cell type (8 of 11) (p = 0.000125). Compared with patients with DLBCL, patients with nasal NK/T-cell lymphoma were overall younger, with a lower male-to-female ratio. Lymphomas of B-cell lineage were more likely to be associated with symptoms related to the eyes (p < 0.0005) and to have extension to the orbit (p < 0.01) than were lymphomas of T- or NK-cell lineage. In contrast to results of Asian studies in which nasal NK/T-cell lymphoma has a very poor prognosis, our nasal NK/T-cell lymphomas had an outcome similar to that of DLBCL.     

The distribution of non-Hodgkin's lymphoma in the lymphoid compartments of the human spleen

In a series of 139 spleens involved by non-Hodgkin's lymphoma, we found that each type of lymphoma (as classified according to the Kiel classification) has a specific pattern of infiltration in the red and white pulp. Tumor infiltration in preexistent follicles was not a feature of B-cell lymphomas, but tumor nodules were found in the red pulp nonfiltering areas in cases of immunocytoma (small lymphocytic plasmacytoid) and centroblastic-centrocytic lymphoma (follicle center-cell lymphoma). B-chronic lymphocytic leukemia and centrocytic-centroblastic lymphoma were located along central arteries of T-cell areas. T-cell areas were infiltrated by B-prolymphocytic leukemia, immunocytoma, centrocytic lymphoma (lymphocytic lymphoma of intermediate differentiation), and T-cell lymphoma/leukemia. The red pulp showed diffuse involvement in leukemic cases. Additionally, there was pericapillary growth in all cases of low-grade B-cell lymphoma. The findings, which are related to the physiological counterparts of the lymphoma cells, contribute to our knowledge of the routes of circulation as well as the homing areas of lymphocytes in the human spleen.     

Cutaneous lymphomas with prominent granulomatous reaction: a potential pitfall in the histopathologic diagnosis of cutaneous T- and B-cell lymphomas

The presence of a granulomatous reaction in lesions of cutaneous lymphomas has been described in the past in several cases. Especially in mycosis fungoides, a "granulomatous" variant of the disease has been well characterized. We studied the clinicopathologic features of cutaneous lymphomas with prominent granulomatous reaction, including both cutaneous T-cell lymphomas and B-cell lymphomas (primary cutaneous lymphoma 22, secondary cutaneous lymphoma one). Biopsies of 23 patients with histopathologic features of cutaneous T-cell lymphoma or cutaneous B-cell lymphoma with prominent granulomatous reaction were included in this study. A prominent granulomatous reaction was defined as the presence of a granulomatous component exceeding 25% of the dermal infiltrate. There were 14 cases of mycosis fungoides, two of subcutaneous panniculitis-like T-cell lymphoma, four of small/medium pleomorphic T-cell lymphoma, one of follicle center cell lymphoma, one of large B-cell lymphoma, and one of secondary cutaneous peripheral T-cell lymphoma. Altogether, a prominent granulomatous reaction could be observed in 1.8% of all patients with cutaneous lymphoma (primary or secondary) registered in the files of the Department of Dermatology of the University of Graz (Graz, Austria), demonstrating that there is a distinct, albeit small, proportion of cases revealing this peculiar reaction pattern. In seven cases a misdiagnosis of granulomatous dermatitis preceded the correct diagnosis for a period of 1-216 months, suggesting that sequential biopsies and complete phenotypic and molecular genetic analyses should be carried out in cases of "unusual" granulomatous dermatitis.     

Profiles of B-cell subsets in immunologically stable renal allograft recipients and end-stage renal disease patients

BackgroundPost-transplantation pharmacotherapies typically employ combinations of immunosuppressive agents that have been designed for targeted inhibition of T-cells and T-cell subsets. Studies of acute and chronic effects of clinically employed immunosuppressive agents on B-cells and B-cell subsets are significantly fewer in number and warrant further investigation. Accordingly, the goal of the present cross-sectional study is to functionally evaluate differences of B-cell subsets in patients with end-stage renal disease (ESRD) and immunologically stable renal transplant patients.Patients and methodsOf 103 patients who underwent renal transplantation, 73 patients were immunologically stable without rejection or infection. Among them, 34 patients were one-year post-transplantation, and 39 patients were five-year post-transplantation. The study also included 35 ESRD patients and 36 healthy volunteers. Flow cytometry identified B-cell subsets in the study groups.ResultsRenal allograft recipients had reduced percentages of total B-cells (CD19+) and regulatory B-cells (B_reg) (CD38^highCD27 + CD24+) compared with healthy controls. The percentage of transitional B-cells (IgM + CD38^highCD24^high) and marginal zone (MZ) B-cells (IgD-CD27+) was reduced in transplant recipients compared with patients with ESRD and healthy volunteers. The highest percentage of plasma cells (PCs) (CD38^highCD27 + CD24-) was in patients with ESRD. In five-year post-transplantation group, CD38^lowCD21- B-cells increased when compared with the other groups. Healthy volunteers and patients with ESRD had fewer unswitched memory (UM) B-cells (IgM + IgD + CD38^lowCD27+), and increased isotype switched memory (ISM) B-cells (IgM-IgD-CD38^lowCD27+). There was no difference in the percentage of naïve B-cells (IgD + CD27-) among diverse groups.ConclusionsThe percentages of the total, transitional, B_reg, PCs, MZ, and UM B-cell subsets in immunologically stable renal allograft recipients were significantly different from healthy controls. However, B-cell subsets in patients with ESRD were minimally different with immunologically stable renal allograft recipients.     

Clinicopathologic Features of B-Cell Lineage Neoplasms With Aberrant Expression of CD3: A Study of 21 Cases

CD3 expression by immunohistochemistry was historically considered restricted to T-lineage or NK-lineage neoplasms but recently has been reported in rare cases of mature B-cell neoplasms, frequently in association with Epstein-Barr virus. Here, we describe the pathologic features of 21 B-cell lineage neoplasms that express CD3 protein by immunohistochemistry: 12 diffuse large B-cell lymphomas (DLBCLs); 2 plasmablastic lymphomas (PBLs); 4 plasma cell neoplasms; 2 Burkitt lymphomas; and 1 nodal follicular lymphoma, grade 3A. CD20 expression was negative or only partially positive in 13/21 cases. Epstein-Barr virus was positive in 3/20 tested cases (2 PBLs and 1 DLBCL). All tested neoplasms (14/14) had clonal immunoglobulin gene rearrangements, and no clonal T-cell gene rearrangements were detected (0/14). The 12 DLBCLs segregated into 2 main groups: 7 demonstrated features of plasmacytic differentiation but did not meet criteria for PBL, and 5 had anaplastic features. In addition to morphology, other features shared among the DLBCLs with plasmacytic differentiation, the plasma cell neoplasms, and the PBLs included extranodal presentation, cytoplasmic localization of CD3, and lack of expression of other T-cell antigens in most cases. In contrast, DLBCLs with anaplastic features and the single follicular lymphoma coexpressed multiple T-cell antigens in a predominantly membranous pattern and presented with nodal disease in a relatively younger patient population. Our data expand the spectrum of morphologic, phenotypic, and clinical features of B-cell neoplasms aberrantly expressing CD3. As these neoplasms often lack typical expression of B-cell antigens, knowledge of these features will help avoid misclassification.     

Development and function of diabetogenic T-cells in B-cell-deficient nonobese diabetic mice

Insulin-dependent diabetes (type 1 diabetes) in the NOD mouse is a T-cell-mediated autoimmune disease. However, B-cells may also play a critical role in disease pathogenesis, as genetically B-cell-deficient NOD mice (NOD.microMT) have been shown to be protected from type 1 diabetes and to display reduced responses to certain islet autoantigens. To examine the requirements for B-cells in the development of type 1 diabetes, we generated a B-cell-naive T-cell repertoire by transplantation of NOD fetal thymuses (FTs) into NOD.scid recipients. Surprisingly, these FT-derived NOD T-cells were diabetogenic in 36% of NOD.scid recipients, despite the absence of B-cells. In addition, T-cells isolated from NOD.microMT mice were diabetogenic in 22% of NOD.scid recipients. Together, these results indicate that B-cells are not an absolute requirement for the generation or effector function of an islet-reactive T-cell repertoire in NOD mice. We suggest that conditions favoring rapid lymphocyte expansion can reveal autoreactive T-cell activity and precipitate disease in genetically susceptible individuals.     

Mediastinal lymphoblastic lymphoma with an immature B-cell immunophenotype.

A 19-year-old woman presented with a large mediastinal mass, histologically shown to be malignant lymphoma of lymphoblastic type (LBL). Immunophenotypic and gene rearrangement analysis unequivocally demonstrated that the neoplasm was of B-cell lineage. The neoplastic cells expressed terminal deoxynucleotidyl transferase, the pan-B cell antigens CD19, CD20, and CD22, and were negative for immunoglobulins and numerous T-cell antigens tested. Southern blot analysis showed rearrangement of one allele of the immunoglobulin heavy chain gene while the immunoglobulin kappa and T-cell receptor beta chain genes were in the germline configuration. Thus, the immunophenotypic and molecular findings in this case correspond to an early stage of B-cell differentiation, the pre-pre B-cell stage as has been named by others. In contrast with LBL of immature T-cell lineage, precursor B-cell LBLs involving the mediastinum are truly rare. Occasional cases have been reported that have arisen elsewhere and subsequently involved the mediastinum at time of relapse or tumor progression. Well-documented examples of immature B-cell LBL arising in the mediastinum are virtually unreported. The site and cell population giving rise to this neoplasm is unknown. However, origin from precursors of normal thymic medullary B cells is proposed as one possibility.     

Cutaneous intravascular NK-cell lymphoma: report of a rare variant associated with Epstein-Barr virus

Intravascular lymphoma (IVL) is a rare variant of non-Hodgkin lymphoma with a predilection for skin and brain. Except a few cases of T-cell lineage, most of the reported cases were large B-cell lymphomas. We encountered a case of cutaneous IVL in a 71-year-old woman presenting with multiple erythematous patches and nodules on her trunk and extremities. The intravascular large cells showed an immunophenotype of CD3epsilon(+);, CD5(-), CD20(-), CD30(-), CD56(+), and TIA-1(+). The lymphoma cells were also positive for Epstein-Barr virus by Epstein-Barr virus-encoded RNA in situ hybridization test and the T-cell receptor gene was germline. This IVL differs from nasal type NK/T-cell lymphoma only by its intravascular nature. Only 3 cases of intravascular NK-cell lymphoma have been reported before. Because this variant is extremely rare, our case is documented and compared with the 3 previously reported cases.     

Rapid destruction of encapsulated islet xenografts by NOD mice is CD4-dependent and facilitated by B-cells: innate immunity and autoimmunity do not play significant roles

BACKGROUND: Spontaneously diabetic NOD mice rapidly reject microencapsulated islet xenografts via an intense pericapsular inflammatory response. METHODS: Tilapia (fish) islets were encapsulated in 1.5% alginate gel microspheres. Recipients in series 1 were spontaneously diabetic NOD mice and streptozotocin-diabetic nude, euthymic Balb/c, prediabetic NOD, and NOR (a recombinant congenic strain not prone to autoimmune diabetes) mice. Recipients in Series 2 were STZ-diabetic NOD, NOD-scid, NOD CD4 T-cell KO, NOD CD8 T-cell KO, and NOD B-cell KO mice. RESULTS: In Series 1, encapsulated fish islet grafts uniformly survived long-term in nude mice but were rejected in Balb/c and, at a markedly accelerated rate, in spontaneously diabetic NOD, streptozotocin-diabetic NOD and NOR recipients. Histologically, intense inflammation (macrophages and eosinophils) surrounding the microcapsules was seen only in NOD and NOR recipients. In Series 2, encapsulated fish islets uniformly survived long-term in NOD-scid and NOD CD4 KO mice; graft survival was markedly prolonged in B-cell KO (P<0.001) but not CD8 KO mice. CONCLUSIONS: The rapid rejection of alginate encapsulated islet xenografts by NOD mice is not solely a consequence of beta-cell directed autoimmunity nor is it merely a vigorous innate immune response. Graft rejection requires CD4 T-cells, is facilitated by B-cells, and does not require CD8 T-cells.     

Intravascular large T-cell or NK-cell lymphoma: a rare variant of intravascular large cell lymphoma with frequent cytotoxic phenotype and association with Epstein-Barr virus infection

Most cases of intravascular large cell lymphoma have a B-cell phenotype, but rare T-cell and natural killer (NK)-cell variants have been reported. We describe the clinicopathologic features of 4 patients (M:F=3:1; age range: 63 to 87; median age: 65) with intravascular large NK/T-cell lymphoma. The skin was the site of presentation in all patients (leg: 1 case; trunk: 1 case; trunk and extremities: 2 cases). Two patients had lesions confined to the skin; in 1 case concomitant involvement of the brain was detected and in 1 case no further studies were carried out. Immunohistology showed positivity for cytotoxic markers in 3/4 cases. One case had an NK phenotype similar to NK/T-cell lymphoma, nasal-type, whereas the other cases could not be precisely classified into specific categories (peripheral T-cell lymphoma, NOS). One of these cases was negative for cytotoxic markers and was positive only for CD2 and CD3 epsilon. Association with Epstein-Barr virus (EBV) was demonstrated in 2 cases by in situ hybridization, whereas 1 case was negative. All our patients had aggressive disease and died between 2 weeks and 7 months from presentation. Analysis of our cases and of those published in the literature shows that intravascular large NK/T-cell lymphoma is a rare, aggressive lymphoma with variable phenotypic features, frequent expression of cytotoxic proteins, true NK-cell phenotype and association with Epstein-Barr virus infection, and common presentation in the skin. Homogeneous studies on larger number of patients and reevaluation of cases published with incomplete phenotypic data would be necessary to gather more information on this extremely rare type of lymphoma.