Angio-immunoblastic T cell lymphoma (AILD-TL) rich in large B cells and associated with Epstein-Barr virus infection. A different subtype of AILD-TL?

Management of Angioimmunoblastic T-Cell Lymphoma (AITL) and other T Follicular Helper Cell lymphomas (TFH PTCL)

Despite the remarkable improvements in the treatment and outcome of patients with aggressive B-cell lymphoma, the peripheral T-cell lymphomas (PTCL) continue to carry a poor prognosis with the presently available treatment options. The PTCL are very rare diseases that account for only 10,000 to 15,000 new cases per year in the United States. The World Health Organization's 2016 classification describes 29 distinct subtypes of PTCL, thus making these both rate and incredibly heterogenous. The 2 most common forms of PTCL, for example, peripheral T-cell lymphoma-not otherwise specified and angioimmunoblastic T-cell lymphoma , have an incidence of only 2500 and 1800 cases per year respectively, in the United States.

[Molecular diagnosis angioimmunoblastic T-cell lymphoma]

AIM

to determine molecular diagnostics routine for different tissue samples in angioimmunoblastic T-cell lymphoma.

MATERIALS AND METHODS

Molecular studies were performed for 84 primary AITL patients. The median age was 61 year (29-81); the male to female ratio was 48/36. T-cell and B-cell clonality was assessed by GeneScan analysis of rearranged T-cell receptor (TCRG, TCRB) and immunoglobulin heavy chain genes. For the quantitative determination of cells with RHOA G17V mutation real - time polymerase chain reaction (PCR) with allele - specific LNA modified primers was used.

RESULTS

In lymph nodes rearrangements of T-cell receptor genes were determined in 76 (90.5%) of 84 patients and were absent in 8 (9.5%) cases. Identification of the same clonal products of the TCRG and TCRB genes in the lymph node and in peripheral blood and/or bone marrow indicated the prevalence of the tumor process and was observed in 64.7% of patients. Clonal products in peripheral blood and/or bone marrow different from those in the lymph node indicated reactive cytotoxic lymphocyte population and were noted in 58.8% of AITL cases. Simultaneous detection of T- and B-cell clonality in the lymph node was observed in 20 (24.7%) of 81 patients. Cells with RHOA G17V mutation were detected in lymph node in 45 (54.9%) of 82 patients. The use of allele - specific PCR with LNA modified primers revealed presence of the tumor cells in peripheral blood in 100% and in bone marrow in 93.9% of patients with G17V RHOA mutation in the lymph nodes.

CONCLUSION

The validity of different molecular assays performed on certain tissue samples for the diagnosis of angioimmunoblastic T-cell lymphoma has been evaluated. Quantitative allele - specific PCR assay for RHOA G17V mutation based on LNA modified primers possesses sufficient sensitivity for tumor process prevalence evaluation and minimal residual disease monitoring.

T cell-rich lymphoid infiltrates with large B cells: a review of key entities and diagnostic approach

Accurate diagnostic interpretation of a lymphoid population composed predominantly of small T cells, together with smaller numbers of large B cells, with or without a nodular architecture, is a common problem faced by the histopathologist. The differential diagnosis of this histological pattern is wide, ranging from reactive conditions such as drug reactions and viral infections, through borderline entities such as immunodeficiency-related lymphoproliferative disorders to lymphomas. The latter includes entities where the large B cells are primarily neoplastic (classical and nodular lymphocyte-predominant Hodgkin lymphomas and T cell/histiocyte-rich large B cell lymphoma) as well as T cell lymphomas such as angioimmunoblastic T cell lymphoma where the large B cells represent an epiphenomenon and may or may not be neoplastic. Several rare variants of these conditions, and the fact that treatment can significantly modify appearances, add to the diagnostic difficulty of these pathological entities. Unlike monomorphic lymphoid infiltrates, the histological pattern of T cell-rich proliferation with large B cells requires close evaluation of the inter-relationship between B cells and T cells, follicular dendritic cells and sometimes other inflammatory cells. Epstein-Barr virus plays a key role in several of these scenarios, and interpreting not only its presence but also its distribution within cellular subgroups is essential to accurate diagnosis and the avoidance of some important diagnostic pitfalls. An understanding of normal immunoarchitecture and lymphoid maturational pathways is also fundamental to resolving these cases, as is a knowledge of their common patterns of spread, which facilitates correlation with clinical and radiological findings.

Response to 5-azacytidine in a patient with TET2-mutated angioimmunoblastic T-cell lymphoma and chronic myelomonocytic leukaemia preceded by an EBV-positive large B-cell lymphoma

We report the case of a patient with a history of Epstein-Barr virus-positive large B-cell lymphoma, who relapsed with an angioimmunoblastic T-cell lymphoma (AITL) associated with a chronic myelomonocytic leukaemia (CMML). We performed targeted next-generation sequencing on CMML and AITL DNA, which revealed mutations of TET2, DNMT3A, SRSF2, NRAS and IDH1, thus confirming that the spectrum of AITL mutations share similarities with myeloid disorders. The frequencies of TET2/DNMT3A and SRSF2 variants could support the hypothesis that TET2/DNMT3A mutations occurred in an early progenitor cell, which later progressed to both the AITL and CMML clones. Treatment with 5-azacytidine led to the complete remission of both diseases. Thus, targeting DNA methylation abnormalities in AITL may be an alternative strategy to chemotherapy. Copyright © 2016 John Wiley & Sons, Ltd.

Angioimmunoblastic T-Cell Lymphoma Presenting with an Acute Serologic Epstein-Barr Virus Profile

Angioimmunoblastic T-cell lymphoma (AITL) is an aggressive peripheral T-cell lymphoma typically characterized by prominent lymphadenopathy and B-symptoms at the time of presentation, polyclonal hypergammaglobulinemia, autoimmune hemolysis and frequent but highly variable involvement of Epstein-Barr virus (EBV). Lymph node biopsy findings typically include effacement of nodal architecture, polymorphic infiltrate, atypical T-cells (usually CD4+/CD10+/PD1+) and prominent proliferations of high endothelial venules and follicular dendritic cells. However, this classic constellation of pathologic findings is often initially obscured by a prominence of EBV+ B-immunoblasts with or without associated peripherally circulating EBV DNA. Here we document the first reported case of an acute serologic EBV profile (VCA-IgM) in a patient with AITL, and we recommend that clinicians maintain a high index of suspicion for AITL in the appropriate clinical scenario, irrespective of Epstein-Barr related findings.

Molecular genetics of peripheral T-cell lymphomas

Peripheral T-cell lymphomas (PTCL) are rare neoplasms that in most instances respond poorly to conventional chemotherapies. Four varieties--PTCL not otherwise specified (NOS), angioimmunoblastic T-cell lymphoma (AITL), ALK+ anaplastic T-cell lymphoma (ALCL), and ALK- ALCL--account for about 60 % of them. Their classification is difficult because of the wide spectrum of morphologic features and the lack of robust immunohistochemical markers. Thus, high-throughput technologies can importantly contribute to their better understanding. In particular, gene expression profiling has cleared the borders among PTCL/NOS, ALK- ALCL and AITL. In fact, gene signatures have been developed even from formalin-fixed paraffin-embedded tissue samples that definitely distinguish one tumor from the other(s). This has important practical implications: for instance on routine diagnostics PTCL/NOS expressing CD30 can be easily confused with ALK- ALCL, but has a much worse prognosis. Therefore, the clear-cut distinction between the two conditions is pivotal to understand the results of ongoing trials with Brentuximab Vedotin, targeting the CD30 molecule. Besides improving the diagnosis, molecular studies have provided the rationale for the usage of novel drugs in the setting of PTCLs, such as ALK inhibitors in ALK+ ALCL, anti-angiogenetic drugs in AITL, and tyrosine kinase inhibitors in PTCL/NOS and ALK+ and ALK- ALCLs.

The microenvironment in T-cell lymphomas: emerging themes

Peripheral T-cell lymphomas (PTCLs) are heterogeneous and uncommon malignancies characterized by an aggressive clinical course and a mostly poor outcome with current treatment strategies. Despite novel insights into their pathobiology provided by recent genome-wide molecular studies, several entities remain poorly characterized. In addition to the neoplastic cell population, PTCLs have a microenvironment component, composed of non-tumor cells and stroma, which is quantitatively and qualitatively variable, and which may have an effect on their pathological and clinical features. The best example is provided by angioimmunoblastic T-cell lymphoma (AITL), a designation reflecting the typical vascularization and reactive immunoblastic content of the tumor tissues. In this disease, a complex network of interactions between the lymphoma cells and the microenvironment exists, presumably mediated by the neoplastic T cells with follicular helper T-cell properties. A better understanding of the crosstalk between neoplastic T or NK cells and their microenvironment may have important implications for guiding the development of novel therapies.

Diagnostic Impact of Molecular Lineage Analysis on Paraffin-Embedded Tissue in Hematolymphoid Neoplasia Reclassified by Current WHO Criteria

BACKGROUND AND OBJECTIVE

By current WHO criteria, most - though not all - cases of hematolymphoid neoplasm can be diagnosed immunomorphologically, diminishing the role of molecular tests for lymphoid antigen receptor clonality in lymphoma diagnosis. Hence, our objective was to glean immunomorphological and molecular correlates from hematolymphoid neoplasms that had remained unresolvable without diagnostic molecular input.

METHODS

Thirty-five such cases were reviewed histologically and with standard immunoperoxidases. In situ hybridization for Epstein-Barr virus (EBV)-encoded RNAs (EBER) was performed on selected cases. PCR amplification of genes encoding T-cell receptors (TcR) and immunoglobulin heavy chains (IgH) [TR and IGH genes, respectively] was performed on whole tissue in all cases, and on microdissected cells in two cases.

RESULTS

Twenty-five cases (71%) requiring diagnostic molecular genotyping had some form of peripheral T-cell lymphoma (PTCL). Twenty (80%) of these were complicated by a proliferation of B-lineage cells, either within the same tissue ('syntopic') as large B cells (LBC) or Reed-Sternberg (RS)-like cells (17 cases), florid lymphoid hyperplasia (two cases, one also with syntopic LBC) or monotypic plasma cells (one case), or at a separate ('metatopic') site as a B-cell lymphoma (two cases, one of which also had syntopic LBC) or Hodgkin lymphoma (HL; one case, also showing syntopic LBC). Fifteen (75%) of these 20 PTCLs with B-lineage proliferation yielded monoclonal TR gene rearrangements, and only two (10%) showed IGH monoclonality, which was transient in one case. Three (18%) of the PTCLs with LBC had originally been misinterpreted as some form of HL. Conversely, of the remaining cases, three of four (75%) that had been diagnosed initially as some form of large cell non-HL (NHL), including two of three that were called 'anaplastic', had to be revised to grade II/syncytial nodular sclerosing (NS) HL, yielding polyclonal TcRgamma gene (TRG) rearrangements, with one case, in addition, disclosing a biallelic clonal IGH gene rearrangement that excluded anaplastic large cell lymphoma.

DISCUSSION/CONCLUSION

Paradoxically, monoclonality of TR rather than IGH gene rearrangement may more often be detectable in a predominantly dispersed ('hodgkinoid'), large B-lineage cell proliferation, consistent with release from immune regulation in the milieu of impaired immunosurveillance within a PTCL. This is compounded by the difficulty in ascertaining clonal IGH gene rearrangements resulting from (1) poor consensus primer hybridization due to somatic hypermutations, and (2) 'dilution' in a T-cell-rich milieu. These same difficulties also account for the long-elusive identification of the RS cell lineage. Conversely, anaplastic lymphoma, which is of non-B lineage, may be mimicked by NSHL, which is of B lineage.

Targeting intratumoral B cells with rituximab in addition to CHOP in angioimmunoblastic T-cell lymphoma. A clinicobiological study of the GELA

BACKGROUND

In angioimmunoblastic T-cell lymphoma, symptoms linked to B-lymphocyte activation are common, and variable numbers of CD20(+) large B-blasts, often infected by Epstein-Barr virus, are found in tumor tissues. We postulated that the disruption of putative B-T interactions and/or depletion of the Epstein-Barr virus reservoir by an anti-CD20 monoclonal antibody (rituximab) could improve the clinical outcome produced by conventional chemotherapy.

DESIGN AND METHODS

Twenty-five newly diagnosed patients were treated, in a phase II study, with eight cycles of rituximab + chemotherapy (R-CHOP21). Tumor infiltration, B-blasts and Epstein-Barr virus status in tumor tissue and peripheral blood were fully characterized at diagnosis and were correlated with clinical outcome.

RESULTS

A complete response rate of 44% (95% CI, 24% to 65%) was observed. With a median follow-up of 24 months, the 2-year progression-free survival rate was 42% (95% CI, 22% to 61%) and overall survival rate was 62% (95% CI, 40% to 78%). The presence of Epstein-Barr virus DNA in peripheral blood mononuclear cells (14/21 patients) correlated with Epstein-Barr virus score in lymph nodes (P<0.004) and the detection of circulating tumor cells (P=0.0019). Despite peripheral Epstein-Barr virus clearance after treatment, the viral load at diagnosis (>100 copy/μg DNA) was associated with shorter progression-free survival (P=0.06).

CONCLUSIONS

We report here the results of the first clinical trial targeting both the neoplastic T cells and the microenvironment-associated CD20(+) B lymphocytes in angioimmunoblastic T-cell lymphoma, showing no clear benefit of adding rituximab to conventional chemotherapy. A strong relationship, not previously described, between circulating Epstein-Barr virus and circulating tumor cells is highlighted.

Pathology and biology of peripheral T-cell lymphomas

Peripheral T-cell lymphomas (PTCLs) represent a heterogeneous group of more than 20 neoplastic entities derived from mature T cells and natural killer (NK) cells involved in innate and adaptive immunity. With few exceptions these malignancies, which may present as disseminated, predominantly extranodal or cutaneous, or predominantly nodal diseases, are clinically aggressive and have a dismal prognosis. Their diagnosis and classification is hampered by several difficulties, including a significant morphological and immunophenotypic overlap across different entities, and the lack of characteristic genetic alterations for most of them. Although there is increasing evidence that the cell of origin is a major determinant for the delineation of several PTCL entities, however, the cellular derivation of most entities remains poorly characterized and/or may be heterogeneous. The complexity of the biology and pathophysiology of PTCLs has been only partly deciphered. In recent years, novel insights have been gained from genome-wide profiling analyses. In this review, we will summarize the current knowledge on the pathobiological features of peripheral NK/T-cell neoplasms, with a focus on selected disease entities manifesting as tissue infiltrates primarily in extranodal sites and lymph nodes.

Angioimmunoblastic T-cell lymphoma of cytotoxic T-cell phenotype containing a large B-cell proliferation with an undersized B-cell clonal product

Angioimmunoblastic T-cell lymphoma is a nodal peripheral T-cell lymphoma considered to be derived from CD4 follicular helper T cells. It is characterized by the proliferation of arborizing vessels, hyperplastic follicular dendritic cells, and a polymorphous lymphoid infiltrate including large B immunoblasts, which could be polyclonal, oligoclonal, or monoclonal. The polymerase chain reaction-based clonality study of lymphoproliferations is increasingly popular in the diagnostic workup. With the commercially available Biomed-2 protocols, lymphoproliferations with amplicons in the expected size ranges are considered clonal, whereas clonal products outside the expected ranges are extremely rare. We presented the case of a 60-year-old male patient with angioimmunoblastic T-cell lymphoma, in which the neoplastic T cells expressed CD8, bcl-6, and programmed death-1. Furthermore, there was a proliferation of large B cells in this tumor. The results of T-cell receptor gene rearrangement study using the Biomed-2 protocols showed clonal rearrangement with amplicons falling within the expected size ranges. Interestingly, the size of the amplicons detected by the Biomed-2 immunoglobulin heavy chain gene (IgH) rearrangement using FR2/JH primers was around 240 bp, slightly smaller than the expected size ranges. Through cloning, sequencing, and BLAST searches, we confirmed that the FR2/JH amplicon was derived from the IgH rearrangement with a deletion of a short segment. Our case illustrates that polymerase chain reaction amplicons outside the expected size ranges may still be clonal products.

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.

Characteristics of cutaneous marginal zone lymphomas with marked plasmacytic differentiation and a T cell-rich background

Primary cutaneous marginal zone lymphoma (MZL) is a common B-cell lymphoma of skin and is characterized by an infiltrate of neoplastic marginal zone B cells typically within the marginal zones of reactive lymphoid follicles and the interfollicular region. However, in our experience, many cases have underemphasized features such as marked plasmacytic differentiation and/or a prominent T-cell component, which may obscure the neoplastic B cells and lead to misdiagnosis. We wanted to draw attention to these features and have studied 15 cases of MZL with marked plasmacytic differentiation, 10 of which had numerous T cells, some with cytologic atypia, and few B cells in the interfollicular region. Plasma cells were monotypic in all cases by in situ hybridization. By polymerase chain reaction, 6 of 8 T cell-rich cases had an IGH gene rearrangement, and none were clonal for T-cell receptor gene. We discuss the terminology, morphologic features, molecular profile, behavior, and differential diagnosis of cutaneous MZL.

The frequency of immunoglobulin heavy chain gene and T-cell receptor gamma-chain gene rearrangements and Epstein-Barr virus in ALK+ and ALK- anaplastic large cell lymphoma and other peripheral T-cell lymphomas

We previously identified a relatively high frequency of B-cell proliferations along with simultaneous T-cell receptor gamma-chain gene (TRG) and immunoglobulin heavy chain gene (IGH) rearrangements in a series of angioimmunoblastic T-cell lymphoma and peripheral T-cell lymphoma, unspecified. Here, we report on a series of 74 peripheral T-cell lymphoma (PTCL) cases composed entirely of specific PTCL subtypes, including 28 cases of ALK+ anaplastic large-cell lymphoma (ALCL), 35 cases of ALK- ALCL, and 11 cases that represent other specific PTCL subtypes. We performed IGH and TRG gene rearrangement studies and in situ hybridization for Epstein-Barr virus (EBV) to determine the frequency of IGH clonality and to investigate the relationship between EBV, clonality, and associated B-cell proliferations. Using BIOMED-2 PCR assays, we detected TRG clones in 64 of 74 (86%) cases and IGH clones in 6 of 74 (8%) cases, with all IGH-positive cases exhibiting a concurrent TRG clone. Despite the detection of occasional IGH clones, there was no correlation between IGH clonality and EBV, and B-cell proliferations were not identified in any of the cases. These findings suggest that other factors contribute to IGH clonality and demonstrate that, in the absence of an associated B-cell proliferation, IGH clonality occurs infrequently (8%) in specific PTCL subtypes.

Angioimmunoblastic T-cell lymphoma

Angioimmunoblastic T-cell lymphoma (AITL) is a rare and aggressive neoplasm clinically characterized by sudden onset of constitutional symptoms, lymphadenopathy, hepatosplenomegaly, frequent autoimmune phenomena, particularly hemolytic anemia and thrombocytopenia, and polyclonal hypergammaglobulinemia. The lymph node histological picture is also distinctive, constituted by a polymorphic infiltrate, a marked proliferation of high endothelial venules, and a dense meshwork of dentritic cells. The neoplastic CD4+ T-cells represent a minority of the lymph node cell population; its detection is facilitated by the aberrant expression of CD10. Almost all cases arbor an EBV infected B-cell population. Patients with AITL have a poor prognosis with conventional treatment, with a median overall survival of less than 3 years. Patients achieving a good clinical response seem beneficiate from a consolidation with high-dose therapy and autologous stem cell transplantation. Constitutional symptoms and autoimmune phenomena, and some times also the neoplastic masses may respond to immunosuppressive or immunomodulatory agents such as thalidomide.

Clinical, biologic, and pathologic features in 157 patients with angioimmunoblastic T-cell lymphoma treated within the Groupe d'Etude des Lymphomes de l'Adulte (GELA) trials

To evaluate the prognostic significance of clinicobiologic and pathological features in angioimmunoblastic T-cell lymphoma (AITL), 157 AITL patients were retrieved from the GELA LNH87-LNH93 randomized clinical trials. One hundred forty-seven patients received a cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP)-like regimen with intensified courses in half of them. Histologically, 41 cases were classified as "rich in large cells" and 116 as "classic" (including 19 rich in epithelioid cells, 14 rich in clear cells, and 4 with hyperplastic germinal centers). Sixty-two cases were scored for CD10 and CXCL13 expression according to the abundance of positive lymphoid cells. Median age was 62 years, with 81% advanced stage, 72% B symptoms, 65% anemia, 50% hypergammaglobulinemia, and 66% elevated LDH. Overall 7-year survival was 30%. In multivariate analysis, only male sex (P = .004), mediastinal lymphadenopathy (P = .041), and anemia (P = .042) adversely affected overall survival. Increase in large cells and high level of CD10 and CXCL13 did not affect survival. Intensive regimen did not improve survival. In conclusion, AITL is a morphologically heterogeneous T-cell lymphoma commonly expressing CXCL13 and CD10 and carrying few prognostic factors. It portends a poor prognosis even when treated intensively. However, AITL is not always lethal with 30% of patients alive at 7 years.

Lymphomes T angio-immunoblastiques

Angioimmunoblastic T-cell lymphoma most often affects the elderly. Patients present with generalized lymphadenopathy and systemic symptoms; half also have hepatomegaly, splenomegaly and a rash. Polyclonal hypergammaglobulinemia, elevated lactate dehydrogenase, and anemia are the main laboratory abnormalities. Autoimmune phenomena (including autoimmune hemolytic anemia, immunologic thrombocytopenia, and autoantibodies) are common. Lymph node biopsy is needed to confirm this diagnosis. Genetic analysis that reveals a monoclonal T-cell population is also relevant. The underlying immune deficiency explains the frequency of infections. Most patients are treated with combination chemotherapy. Autologous stem cell transplantation is proposed to the youngest. Immunosuppressive drugs may be appropriate for elderly or relapsing patients. The overall 5-year survival rate is 30%.

Epstein-Barr Virus Negative Clonal Plasma Cell Proliferations and Lymphomas in Peripheral T-cell Lymphomas

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.

Characterization of CXCL13+ Neoplastic T Cells in Cutaneous Lesions of Angioimmunoblastic T-cell Lymphoma (AITL)

Skin manifestations of angioimmunoblastic T-cell lymphoma (AITL) are frequent, sometimes as first manifestations of the disease. In the absence of a specific marker for neoplastic cells, diagnosis of AITL in skin biopsies is often difficult. CD10 and CXCL13 have been recently recognized as characteristic markers of AITL, but have not been yet investigated in the skin. We analyzed 15 skin biopsies from 8 patients with AITL having skin manifestations and compared them to 14 skin biopsies from patients with various cutaneous lymphocytic infiltrates. A few CD10 lymphocytes were found in only 2 samples of the AITL group, the identification of which was hampered by the presence of a dermal CD10 cell population with dendritic features. By contrast, CXCL13 lymphoid cells were identified in most AITL cutaneous biopsies (n=12, 80%), whereas, absent in all samples from control cases. Among 12 biopsies with CXCL13 cells, cutaneous involvement by AITL was suspected in only 5 on the basis of light microscopy and classic immunophenotyping. In another case, a diagnosis of cutaneous marginal zone B-cell lymphoma had been proposed. In conclusion, this study shows that neoplastic AITL CXCL13 T cells localize in the skin and that accurate diagnosis of AITL lesions can be done in skin specimens using CXCL13 immunostaining on paraffin-embedded tissues.

Powerful strategy for polymerase chain reaction-based clonality assessment in T-cell malignancies Report of the BIOMED-2 Concerted Action BHM4 CT98-3936

Polymerase chain reaction (PCR) assessment of clonal T-cell receptor (TCR) and immunoglobulin (Ig) gene rearrangements is an important diagnostic tool in mature T-cell neoplasms. However, lack of standardized primers and PCR protocols has hampered comparability of data in previous clonality studies. To obtain reference values for Ig/TCR rearrangement patterns, 19 European laboratories investigated 188 T-cell malignancies belonging to five World Health Organization-defined entities. The TCR/Ig spectrum of each sample was analyzed in duplicate in two different laboratories using the standardized BIOMED-2 PCR multiplex tubes accompanied by international pathology panel review. TCR clonality was detected in 99% (143/145) of all definite cases of T-cell prolymphocytic leukemia, T-cell large granular lymphocytic leukemia, peripheral T-cell lymphoma (unspecified) and angioimmunoblastic T-cell lymphoma (AILT), whereas nine of 43 anaplastic large cell lymphomas did not show clonal TCR rearrangements. Combined use of TCRB and TCRG genes revealed two or more clonal signals in 95% of all TCR clonal cases. Ig clonality was mostly restricted to AILT. Our study indicates that the BIOMED-2 multiplex PCR tubes provide a powerful strategy for clonality assessment in T-cell malignancies assisting the firm diagnosis of T-cell neoplasms. The detected TCR gene rearrangements can also be used as PCR targets for monitoring of minimal residual disease.

The frequency of B- and T-cell gene rearrangements and epstein-barr virus in T-cell lymphomas: a comparison between angioimmunoblastic T-cell lymphoma and peripheral T-cell lymphoma, unspecified with and without associated B-cell proliferations

We report on a series of 58 cases of angioimmunoblastic T-cell lymphoma (AILT) and 59 cases of peripheral T-cell lymphoma, unspecified (PTCL-NOS). Subsets of cases from both diagnostic groups were complicated by associated B-cell proliferations, and we performed B- and T-cell clonality studies and in situ hybridization for Epstein-Barr virus (EBV) to investigate the relationship between B-cell proliferation, B-cell clonality, and EBV. Using multiplex polymerase chain reaction assays based on the BIOMED-2 collaborative study, we detected TCRgamma T-cell clones in 78 and 81% of AILT and PTCL-NOS cases, respectively, and IGH B-cell clones in 34 and 35% of AILT and PTCL-NOS cases, respectively. The majority of cases contained EBV-positive cells, including 50% of AILT and 57% of PTCL-NOS cases, and cases with B-cell proliferations were more often EBV-positive. Although a relatively high rate of B-cell clonality has been shown for AILT, our findings for PTCL-NOS differ from previous reports in that B-cell clonality was relatively frequent. Overall, a positive B-cell clone correlated, in part, with the presence of a B-cell proliferation but not with EBV. Our findings demonstrate that B-cell clonality is a common finding in AILT and PTCL-NOS, and its presence should not negate the diagnosis established by morphologic, immunophenotypic, and clinical findings.

Primary Cutaneous Lymphoproliferative Disorders With Dual Lineage Rearrangement

We present a series of 15 cases of cutaneous lymphoma and pseudolymphoma with dual lineage rearrangement identified among approximately 1200 cases of cutaneous lymphoproliferative disorders assessed in our 4 institutions during the last 8 years in which the results of both T-cell receptor and immunoglobulin heavy chain rearrangement investigations were available. On the basis of the clinicopathologic information, the cases were retrospectively subdivided into 2 categories: (1) cases with definite features of cutaneous lymphoma or pseudolymphoma (n = 11) and (2) cases with unclassifiable disease (n = 4). The detection of dual genotype in the first group did not influence the final diagnosis; 7 cases represented cutaneous B-cell lymphomas, 3 pseudolymphomas, and 1 case lymphomatoid papulosis. The presence of monoclonal T-cell receptor-gene rearrangements in these cases may be explained either by monoclonal or oligoclonal expansion of exuberant T cells (or B cells in case of lymphomatoid papulosis) or by lineage infidelity. Three patients with unclassifiable disease had several clinical and histopathologic features in common. They were elderly, presented with solitary lesions, were in good general health and histopathologically demonstrated a dense multinodular infiltrate containing approximately an equal number of T and B cells and a high number of histiocytes forming granulomas, with prominent granulomatous features in 2 cases. B cells were either scattered with the infiltrate or formed collections vaguely resembling follicles; Reed-Sternberg-like cells were seen in 2 cases. B cells showed expression neither of immunoglobulin light chain. The T-cell component was represented mainly by small, well-differentiated lymphocytes or slightly pleomorphic cells, with some medium-sized convoluted cells. Epstein-Barr virus was not detected by polymerase chain reaction. The exact classification of these cases is unknown; they differ histopathologically from previously published cases of bigenotypic cutaneous lymphomas. They may merely represent a growth or reactive pattern, but, on the other hand, may be low-grade lymphomas. If so, they may be histopathologically related to cutaneous Hodgkin disease, T-cell/histiocyte-rich large B-cell lymphoma, or composite lymphomas. Further reports are needed to identify these lesions to clarify their nature and biologic potential.

Expression of CXCL13 by Neoplastic Cells in Angioimmunoblastic T-Cell Lymphoma (AITL)

Angioimmunoblastic T-cell lymphoma (AITL) represents a distinct entity among peripheral T-cell lymphomas (PTCLs). The cellular origin of AITL remains unknown, although a possible derivation from follicular helper T cells (TFH) has been suggested based on the CD4/Bcl-6 phenotype. It has been recently shown that expression of CXCL13, a chemokine critically involved in B-cell migration into germinal centers, is characteristic of TFH cells, as compared with other T helper subsets. We compared CXCL13 expression in 29 AITLs, 20 PTCLs, unspecified, 10 anaplastic large cell lymphomas (ALCL), and 4 other PTCLs. We showed that CXCL13 is expressed by AITL (29 of 29, 100%) and a subset of PTCL, unspecified (6 of 20, 30%), which all showed borderline features with AITL, but in only 1 of 10 (10%) ALCLs, and 0 of 4 other PTCLs. Two-color immunostainings further showed that CXCL13 was found in the cytoplasm of atypical CD5-positive T cells that expressed CD10. We conclude that CXCL13 expression is a common characteristic of AITL, which can help to delineate the morphologic spectrum of the disease, and further supports its derivation from TFH cells. CXCL13 expression may also provide an additional useful tool for the diagnosis of AITL.

CD10 expression in peripheral T-cell lymphomas complicated by a proliferation of large B-cells

CD10 expression by the neoplastic T cells in angioimmunoblastic T-cell lymphoma was recently described. As cases of peripheral T-cell lymphoma, unspecified, fail to show similar CD10 expression, this feature helps discriminate between these two entities, particularly in cases exhibiting morphologic overlap. Given these findings, we studied CD10 expression in a subtype of peripheral T-cell lymphoma known as peripheral T-cell lymphoma complicated by a proliferation of large B cells and compared it with angioimmunoblastic T-cell lymphoma and angioimmunoblastic T-cell lymphoma with a large B-cell proliferation. A total of 33 cases were identified including peripheral T-cell lymphoma complicated by a proliferation of large B cells (10), angioimmunoblastic T-cell lymphoma (10) and angioimmunoblastic T-cell lymphoma with a large B-cell proliferation (13). Diagnoses were established by hematoxylin and eosin (H&E) stain, immunohistochemistry and/or molecular findings (polymerase chain reaction for T-cell receptor-gamma gene rearrangement). Two of 10 cases of peripheral T-cell lymphoma complicated by a proliferation of large B cells showed aberrant CD10 expression (20%) compared to 9/10 cases of angioimmunoblastic T-cell lymphoma (90%) and 8/13 of angioimmunoblastic T-cell lymphoma with a large B-cell proliferation (62%). One case each of angioimmunoblastic T-cell lymphoma and angioimmunoblastic T-cell lymphoma with a large B-cell proliferation showed a rare, but not unequivocal, CD10+ atypical cell. Four cases of angioimmunoblastic T-cell lymphoma with a large B-cell proliferation were CD10 negative. Of the 2 CD10+ peripheral T-cell lymphoma complicated by a proliferation of large B cells, one had no H&E or IHC features of angioimmunoblastic T-cell lymphoma and showed only a rare positive cell. The second case, a lung biopsy, exhibited diffuse CD10 tumor cell positivity. The predominant staining pattern in the CD10+ cases was characterized by scattered, mostly individual, morphologically neoplastic cells. A rare case showed clusters of positive cells. Our data indicate that only 20% of cases of peripheral T-cell lymphoma complicated by a proliferation of large B cells show CD10 expression by the neoplastic T cells in contrast to angioimmunoblastic T-cell lymphoma and angioimmunoblastic T-cell lymphoma with a large B-cell proliferation which exhibit CD10 staining in 90 and 62% of cases, respectively. This finding does not reach statistical significance with a P-value of 0.57 (Fisher's exact test). As these entities appear to be biologically distinct and may portend different overall survivals, CD10 expression may serve as an additional discriminating criterion.

Angioimmunoblastic T cell lymphoma with an unusual proliferation of Epstein-Barr virus-associated large B cells arising in a patient with progressive systemic sclerosis

We report an unusual case of angioimmunoblastic T cell lymphoma arising in the setting of 5 years of immunosuppressive treatment for progressive systemic sclerosis. The lymph node lesion was accompanied by large blastic B cells with an association of Epstein-Barr virus. Southern blot study demonstrated the clonal rearrangement of T cell receptor beta-chain gene, but not of immunoglobulin heavy chain gene. Phenotypical examination of the lymph node also revealed the predominance of CD4+ T cells in addition to the proliferation of follicular dendritic cells, but no light chain restriction in large B cell components. In the clinical and laboratory aspects, neutrophilia (15.8 x 10(9)/l) and plasmacytosis (40%) in bone marrow were noted, which were considered to be closely related to elevated serum granulocyte colony-stimulating factor, interleukin (IL)-4 and IL-6. Based on the combined data described here, our preferred diagnosis was angioimmunoblastic T cell lymphoma with Epstein-Barr virus-associated B cell lymphoproliferative disorder, the pathogenesis of which was suggested to be closely associated with immunosuppressive treatment for progressive systemic sclerosis.