The curious origins of angioimmunoblastic T-cell lymphoma.

PURPOSE OF REVIEW: Once an obscure disease, recent studies have transformed our understanding of angioimmunoblastic T-cell lymphoma (AITL). In this review, we summarize new major advances in the genetics and biology of AITL. RECENT FINDINGS: Genome wide sequencing studies have dissected the repertoire of the genetic alterations driving AITL uncovering a highly recurrent Gly17Val somatic mutation in the small GTPase RHOA and major role for mutations in epigenetic regulators, such as TET2, DNMT3A and IDH2, and signaling factors (e.g., FYN and CD28). These findings support a multistep model of follicular T helper cell transformation in AITL and pinpoint novel candidates for the development of targeted therapies in this disease. SUMMARY: AITL originates from follicular T helper cells and is characterized by the presence of RHOA G17V mutation together with genetic alterations in TET2, DNMT3A, and IDH2. Research efforts now focus on the elucidation of the specific roles and interplay of these genetic alterations in the pathogenesis of AITL.

Molecular mechanisms of angioimmunoblastic T-cell lymphoma development.

The molecular pathogenesis of peripheral T-cell lymphoma (PTCL) has gradually been clarified in terms of genomic abnormalities. Insights into these genomic abnormalities have provided clues to understanding the pathogenesis of PTCL. Furthermore, the origins of lymphoma cells have been clarified by investigating the distribution of genomic abnormalities in tumor cells and non-tumor blood cells. Multistep tumorigenesis has been suggested to be a fundamental mechanism underlying the development of angioimmunoblastic T-cell lymphoma (AITL), a distinct subtype of PTCL: premalignant cells evolve from hematopoietic progenitors via mutations in epigenetic regulators. These cells then further differentiate into tumor cells via the addition of tumor-specific G17V RHOA mutations. Meanwhile, AITL are composed of various infiltrating cells as well as tumor cells. Most notably, AITL tissues are characterized by massive infiltration of B cells partially infected by Epstein-Barr virus, follicular dendritic cells, and high endothelial venules. Infiltration of these cell types has been thought to be a reactive process, promoted by cytokines and chemokines released from tumor cells. Considering the multistep mechanisms of AITL allows us to analyze whether these infiltrating cells are also derived from premalignant cells. Indeed, the mechanisms underlying massive infiltration of bystander cells might be more complicated than previously imagined.

Aberrant immunoarchitecture distinguishes hyperplastic germinal centres in pattern 1 angioimmunoblastic T-cell lymphoma from reactive follicles.

We compare 30 biopsies each of Pattern 1 angioimmunoblastic T-cell lymphoma (AITL1) and reactive lymphoid hyperplasia (RLH) by immunohistology, in-situ hybridization for Epstein-Barr virus-encoded RNA and T-cell receptor-γ (TRG)-clonality. AITL1 cases, more often than RLH controls, were older [median ages 61 (range 23-79) vs 46 (range 11-59) years, p < 10(-4)], non-Chinese [16/30 (53%) vs 8/28 (29%), p = 0.035], presented nodally [29/30 (97%) vs 23/30 (77%), p = 0.024], showed: pan-T cell antigen attenuation [25/29 (86%) vs 5/21 (24%), p = 1.0 × 10(-5)], CD4 predominance [25/28 (89%) vs 12/23 (52%), p = 3.4 × 10(-3)], interfollicular lymphoid CD10-positivity [16/30 (53%) vs 1/29 (3%), p = 1.5 × 10(-5)], TRG clonality [16/28 (57%) vs 1/20 (5%), p = 1.4 × 10(-4)], higher maximum number of Epstein-Barr virus-encoded RNA + nuclei per 0.5-mm high-power field [median 6 (range 0-70) vs 1 (range 0-40), p = 0.012] and interfollicular Ki-67 proliferation fraction [median 40% (range 10-80%) vs 20% (range 5-40), p < 10(-4)], whereas their germinal centres (GCs) more often showed attenuation of CD10 [30/30 (100%) vs 11/29 (38%), p = 5.3 × 10(-8)] and CD57 [18/25 (72%) vs 4/22 (18%), p = 2.4 × 10(-4)] (respectively). GC-predominant PD-1 and ICOS immunoreactivity were more often seen in RLH [20/22 and 9/19 controls (91% and 47%)] than AITL1 [9/25 and 3/19 cases (36% and 16%), p = 1.0 × 10(-4) and 0.033, respectively]. Significant independent predictors against AITL1 were: solid GC CD10 immunoreactivity {p = 0.023, odds ratio (OR) for AITL1 0.01 [95% confidence interval (CI): 0.0002-0.529]}; lower interfollicular proliferation fraction [p = 0.047, OR for AITL1 1.1 (95% CI: 1.001-1.209) per % rise in Ki-67]; younger presenting age [p = 0.028, OR for AITL1 1.136 (95% CI: 1.014-1.272) per year older]. Hence, GCs and perifollicular zones in AITL1 are distinct from those in RLH.

Inhibition of choline metabolism in an angioimmunoblastic T-cell lymphoma preclinical model reveals a new metabolic vulnerability as possible target for treatment.

BACKGROUND: Angioimmunoblastic T-cell lymphoma (AITL) is a malignancy with very poor survival outcome, in urgent need of more specific therapeutic strategies. The drivers of malignancy in this disease are CD4+ follicular helper T cells (Tfh). The metabolism of these malignant Tfh cells was not yet elucidated. Therefore, we decided to identify their metabolic requirements with the objective to propose a novel therapeutic option. METHODS: To reveal the prominent metabolic pathways used by the AITL lymphoma cells, we relied on metabolomic and proteomic analysis of murine AITL (mAITL) T cells isolated from our established mAITL model. We confirmed these results using AITL patient and healthy T cell expression data. RESULTS: Strikingly, the mAITL Tfh cells were highly dependent on the second branch of the Kennedy pathway, the choline lipid pathway, responsible for the production of the major membrane constituent phosphatidylcholine. Moreover, gene expression data from Tfh cells isolated from AITL patient tumors, confirmed the upregulation of the choline lipid pathway. Several enzymes involved in this pathway such as choline kinase, catalyzing the first step in the phosphatidylcholine pathway, are upregulated in multiple tumors other than AITL. Here we showed that treatment of our mAITL preclinical mouse model with a fatty acid oxydation inhibitor, significantly increased their survival and even reverted the exhausted CD8 T cells in the tumor into potent cytotoxic anti-tumor cells. Specific inhibition of Chokα confirmed the importance of the phosphatidylcholine production pathway in neoplastic CD4 + T cells, nearly eradicating mAITL Tfh cells from the tumors. Finally, the same inhibitor induced in human AITL lymphoma biopsies cell death of the majority of the hAITL PD-1high neoplastic cells. CONCLUSION: Our results suggest that interfering with choline metabolism in AITL reveals a specific metabolic vulnerability and might represent a new therapeutic strategy for these patients.

BCL2 expression in CD105 positive neoangiogenic cells and tumor progression in angioimmunoblastic T-cell lymphoma.

The angiogenic microenvironment has been known to be a component of angioimmunoblastic T-cell lymphoma since its initial characterization. We have shown that angioimmunoblastic T-cell lymphoma endothelial cells produce vascular endothelial growth factor-A (VEGFA), and participate in lymphoma progression. In squamous cell carcinoma, endothelial BCL2 expression induces a crosstalk with tumor cells through VEGFA, a major mediator of tumoral angiogenesis. In the present study, we analyzed BCL2 and VEGFA in 30 angioimmunoblastic T-cell lymphomas, using triple immunofluorescence to identify protein coexpression in well-characterized lymphoma cells and microenvironment neoangiogenic endothelial cells. Using quantitative real-time PCR, we assessed mRNA expression levels in laser-microdissected endothelial and lymphoma cells. In lymphoma cells, as in endothelial cells, BCL2 and VEGFA proteins were coexpressed. BCL2 was expressed only in neoangiogenic CD34(+)CD105(+) endothelial cells. In laser-microdissected cells, mRNA studies showed a significant relationship between BCL2 and VEGFA levels in CD34(+) endothelial cells, but not in CD3(+)CD10(+)lymphoma cells, or in CD34(+) endothelial cells from lymph node hyperplasia. Further study showed that, in AITL, BCL2 mRNA levels in CD34(+)CD105(+) neoangiogenic endothelial cells also correlated with microvessel density, International Prognostic Index, Ann Arbor stage, bone marrow involvement and elevated LDH. BCL2 expression by CD105(+) neoangiogenic endothelial cells is related to tumor progression in angioimmunoblastic T-cell lymphoma.

Epidermotropic secondary cutaneous involvement by relapsed angioimmunoblastic T-cell lymphoma mimicking mycosis fungoides: a case report.

Angioimmunoblastic T-cell lymphoma (AITL) is frequently associated with skin lesions, but epidermotropic cutaneous involvement has never been described. A 37-year-old man presented with erythematous and pruriginous plaques, clinically suggestive of mycosis fungoides, distributed all over the body, 3 weeks after the last line of a polychemotherapy, given for an AITL diagnosed 1 year earlier on a lymph node biopsy. Skin biopsy showed an epidermotropic CD4(+) T-cell lymphoma, so that a diagnosis of mycosis fungoides was first proposed. Further investigations showed that atypical lymphocytes strongly expressed CD10 and markers of follicular helper T cells (T(FH) ) including PD1, BCL-6 and CXCL13. The diagnosis of an unusual epidermotropic cutaneous localization of the AITL was finally made, supported by the presence of the same T-cell clone in the initial lymph node biopsy and the skin. We therefore recommend performing markers of T(FH) cells in patients with unusual epidermotropic cutaneous T-cell lymphomas, particularly if they have any clinical features suggestive of AITL.

CD10 and ICOS expression by multiparametric flow cytometry in angioimmunoblastic T-cell lymphoma.

Angioimmunoblastic T-cell lymphoma is immunologically defined by the expression of CD10 and the follicular helper T cell (T(FH)) markers such as CXCL13, programmed death-1 (PD-1) and inducible T-cell costimulator (ICOS). This T(FH) profile has been mainly reported by immunohistochemistry. Here, using multiparametric flow cytometry, the relevance of ICOS and PD-1 to angioimmunoblastic T-cell lymphoma diagnosis was evaluated in lymph node (n=15) as well as in peripheral blood (n=13) among a series of 28 angioimmunoblastic T-cell lymphoma cases, in addition to the CD10 expression (available in 26 lymph node and 15 peripheral blood specimens). In this series, CD10 expression was present in 23/26 (88%) lymph node and in 12/15 (80%) peripheral blood cases and ICOS in 13/15 (87%) lymph node and in 6/13 (47%) peripheral blood cases, whereas neither significant CD10 nor ICOS T cells were identified in the control group (lymph nodes with reactive hyperplasia=10, peripheral blood of healthy donors=15). PD-1 expression was less informative as observed in both angioimmunoblastic T-cell lymphoma and control cases. The multiparametric approach allowed us to confirm the frequent blood dissemination in angioimmunoblastic T-cell lymphoma and to show that circulating neoplastic T cells correspond more often to a CD10-positive subset than to an ICOS-positive subset. Consequently, if ICOS constitutes an additional feature for the diagnosis of angioimmunoblastic T-cell lymphoma, it appears less sensitive than CD10 expression for the detection of circulating neoplastic T cells.

[Follicular variant of peripheral T-cell lymphoma: a clinicopathologic and genetic study of 2 cases].

OBJECTIVE: To observe the clinicopathologic and genetic features of follicular variant of peripheral T-cell lymphoma (FV-PTCL), with particular attention to the relationship of this type of lymphoma with angioimmunoblastic T-cell lymphoma (AITL). METHODS: The clinical data, hematoxylin and eosin-stained sections of lymph node biopsies from 2 FV-PTCL cases were reviewed. Immunohistochemical phenotyping and detection of EBV-encoded RNAs (EBER) through in situ hybridization (ISH) were performed. The EnVision two-step method was used for all antibodies except CXCL13 (by using three-step streptavidin immunoperoxidase method). Analysis of clonality and ITK/SYK gene rearrangement was conducted using PCR and RT-PCR assays, respectively. RESULTS: Clinically, the two patients presented with superficial lymphadenopathy similarly. Histologically, case 1 showed a follicular/nodular lymphoid proliferation without marked germinal centers. The neoplastic cells comprised mainly medium sized cells with abundant, sometimes clear cytoplasms. Similar histologic findings were seen in case 2 in addition to a concurrent component mimicking typical AITL noticed. Of both cases, the neoplastic cells showed positive reactivity to CD3, CD4, CD10, PD1, and CXCL13. Positive hybridization signals for EBER were only seen in case 2, and double stains demonstrated that those EBV-positive cells were mostly the reactive transformed B-cells. Monoclonal T-cell proliferation was proved by the rearranged TCR gene detection in both cases. Neither of the current cases expressed ITK/SYK fusion transcripts. CONCLUSION: FV-PTCL shows the similar or overlapped morphological and immunophenotypic features to those of AITL, possibly suggesting the presence of a potential relationship between these two types of lymphomas.

The inducible T-cell co-stimulator molecule is expressed on subsets of T cells and is a new marker of lymphomas of T follicular helper cell-derivation.

BACKGROUND: T follicular helper (T(FH)) cells reside in the light zone of germinal centers and are considered the cell of origin of angioimmunoblastic T-cell lymphoma. Recently, CXCL13, PD-1 and SAP were described as useful markers for T(FH) cells and angioimmunoblastic T-cell lymphoma but also reported in some peripheral T-cell lymphomas, not otherwise specified. DESIGN AND METHODS: In the present study the expression pattern of ICOS protein was investigated by immunohistochemistry-based techniques in routine sections of normal lymphoid tissues and 633 human lymphomas. RESULTS: Cells strongly positive for ICOS were restricted to the light zone of germinal centers and co-expressed T(FH)-associated molecules. In addition, weak to moderate ICOS expression was observed in a small proportion of FOXP3-positive cells. In lymphomas, ICOS expression was confined to angioimmunoblastic T-cell lymphoma (85/86), peripheral T-cell lymphomas of follicular variant (18/18) and a proportion of peripheral T-cell lymphomas, not otherwise specified (24/56) that also expressed other T(FH)-associated molecules. CONCLUSIONS: ICOS is a useful molecule for identifying T(FH) cells and its restricted expression to angioimmunoblastic T-cell lymphoma and a proportion of peripheral T-cell lymphomas, not otherwise specified (showing a T(FH)-like profile) suggests its inclusion in the antibody panel for diagnosing T(FH)-derived lymphomas. Our findings provide further evidence that the histological spectrum of T(FH)-derived lymphomas is broader than previously assumed.

[Clinicopathologic study of 963 cases of mature T-cell and natural killer/T-cell lymphoma with respect to 2008 WHO classification of lymphoid neoplasms].

OBJECTIVE: To study the clinicopathologic features of various types of mature T-cell and natural killer (NK)/T-cell lymphoma in Guangdong, China, with respect to the 2008 WHO classification of lymphoid neoplasms. METHODS: Eleven hundred and thirty-seven (1137) cases of mature T-cell or NK/T-cell lymphoma diagnosed during the period from 2002 to 2006 in Guangzhou area were retrieved. The clinical data, histologic features and immunohistochemical findings were reviewed by a panel of experienced hematopathologists. Additional immunostaining was performed if indicated. The cases were re-classified according to the 2008 WHO classification of lymphoid neoplasms. RESULTS: Nine hundred and sixty-three (963) cases fulfilled the diagnostic criteria of mature T-cell or NK/T-cell lymphoma and accounted for 20.1% of all cases of lymphoma encountered during the same period (963/4801). A predominance of extranodal involvement was noted in 644 cases (66.9%), while 319 cases (33.1%) showed mainly nodal disease. The prevalence of various lymphoma subtypes was as follows: peripheral T-cell lymphoma, unspecified (PTCL, NOS) 293 cases (30.4%), extranodal NK/T-cell lymphoma, nasal type 281 cases (29.2%), anaplastic large cell lymphoma (ALCL) 198 cases (20.6%), and angioimmunoblastic T-cell lymphoma (AILT) 46 cases (4.8%). The male-to-female ratio was 1.99. The median age of the patients was 44 years, with the peak age of PTCL, NOS, extranodal NK/T-cell lymphoma, nasal type and AILT being 55 to 64 years, 25 to 54 years and 65 to 74 years, respectively. ALK-positive ALCL occurred more frequently in young age, while the ALK-negative ALCL cases occurred mainly in the elderly. CONCLUSIONS: Extranodal lesions predominate in mature T-cell and NK/T-cell lymphomas occurring in Guangzhou area. There is a male predominance and the overall incidence shows no increasing trend with age of the patient. The peak age of various subtypes however varies. The most common subtype was PTCL, NOS, followed by extranodal NK/T-cell lymphoma, nasal type, ALCL and AILT. The relatively frequent occurrence of extranodal NK/T-cell lymphoma, nasal type in Guangdong area is likely associated with the high incidence of Epstein-Barr virus infection there.

In Situ Characterization of Follicular Helper CD4 T Cells Using Multiplexed Imaging.

Follicular helper CD4 T (Tfh) cells play an essential role in the formation of germinal centers (GCs), where mature B cells proliferate, differentiate, and provide long-term protective humoral responses. Despite the extensive phenotypic characterization and identification of human Tfh cell subsets, their spatial positioning at tissue level is not well understood. Here, we describe a quantitative multiplexed immunofluorescence approach allowing for the comprehensive in situ characterization of Tfh cells in human tonsils and lymph nodes (LNs) from individuals with angioimmunoblastic T-cell lymphoma (AITL). We have developed eight multiplexed panels comprising a spectrum of Tfh cell markers, like PD-1, CXCR5, and ICOS, along with transcription factors (Bcl6, Tbet, GATA3), to assess their expression, frequencies, spatial distribution and co-localization in a quantitative manner. Combined analysis of relevant markers revealed the presence of several Tfh cell subsets at tissue level based on the differential expression of surface receptors, nuclear factors as well as their distinct localization within the follicular areas. Interestingly, we found a considerable amount of tonsillar Tfh cells expressing high levels of the Th2 regulator GATA3. The co-expression of GATA3, CXCR5, and BCL6, points to an important role of GATA3 for the generation of effector human Tfh cells. Furthermore, our data revealed significantly different Tfh cell profile signatures between health and disease. Therefore, our imaging platform generates meaningful information for the in situ characterization of human Tfh cells and could provide the base for future studies aiming to a comprehensive understanding of Tfh cell tissue heterogeneity.

Bone Marrow Infiltration of Angioimmunoblastic T-Cell Lymphoma: Identification and Prognostic Impact of Histologic Patterns and Diagnostic Application of Ancillary Phenotypic and Molecular Analyses.

CONTEXT.­: Angioimmunoblastic T-cell lymphomas originate from T follicular helper cells and express respective markers (BCL6, CD10, CXCL13, ICOS, and PD-1). Although commonly present, bone marrow involvement by angioimmunoblastic T-cell lymphoma can be diagnostically challenging. Additionally, only little is known about the distribution of T follicular helper cells in healthy and reactively changed bone marrows or in samples affected by other lymphomas. OBJECTIVE.­: To establish a diagnostic approach to reliably identify bone marrow infiltration of angioimmunoblastic T-cell lymphoma. DESIGN.­: We analyzed the morphologic infiltration pattern and the expression of T follicular helper-cell markers in 42 matched paired lymph node and bone marrow samples and applied comparative clonality testing. Furthermore, we studied the expression of BCL6 and PD-1 in a control cohort of healthy, reactively changed, and otherwise affected bone marrows. RESULTS.­: We identified 3 different bone marrow infiltration patterns correlating with overall survival (interstitial/micronodular infiltration with or without eosinophilia and diffuse infiltration with eosinophilia). The matched pairs showed a consistent (co)expression of PD-1 and BCL6 with a generally weaker expression in the bone marrow than in the lymph nodes. Comparative clonality testing was helpful in only a minority of cases. Infiltrates of the most important differential diagnoses contained either PD-1- or BCL6-positive tumor-infiltrating cells, but no coexpressing cells. CONCLUSIONS.­: Bone marrow infiltration by angioimmunoblastic T-cell lymphoma displays 3 different patterns that correlate with prognosis. BCL6 and PD-1 can be reliably used to identify lymphoma infiltrates and to help rule out several differential diagnoses. Comparative clonality testing rarely provides additional value and cannot replace morphologic and phenotypic analyses.

[Morphologic and immunophenotypic analysis of angioimmunoblastic T-cell lymphoma].

OBJECTIVE: To study the morphologic and immunophenotypic features of angioimmunoblastic T-cell lymphoma (AITL), as well as the origin of the proliferative follicular dendritic cells (FDCs) in AITL. METHODS: Immunohistochemical study for CD10, CXCL13, bcl-6 and CD21 was performed on 29 cases of AITL. Double immunostaining for bcl-6/CD3, CD10/CD21 and CD10/CD20 were also carried out. Cases of peripheral T-cell lymphoma, unspecified, extranodal NK/T-cell lymphoma, nasal-type, enteropathy-type T-cell lymphoma, anaplastic large cell lymphoma, subcutaneous panniculitis-like T-cell lymphoma and reactive lymphoid proliferation were selected as controls. RESULTS: Amongst the 29 cases of AITL studied, 75.9% (22/29) showed aberrant expression of CD10, while all except one of the controlled cases were negative, 82.8% (24/29) of the AITL cases expressed CXCL13, while all cases of peripheral T-cell lymphoma, unspecified were negative. As for bcl-6 staining, although the highest percentage of bcl-6-positive cells was observed in AITL, the expression pattern was not useful in differentiating AITL from peripheral T-cell lymphoma, unspecified and lymphoid reaction. Besides, all cases of AITL demonstrated the characteristic proliferation of follicular dendritic cells. Two of the cases, which contained obvious germinal centers, had the follicular dendritic cell meshwork extending beyond the lymphoid follicles. CONCLUSIONS: As compared with bcl-6, CD10 and CXCL13 are specific and sensitive markers in diagnosing AITL. Part of the proliferative FDCs in AITL may originate from the germinal centers.

[Expressions of CXCL13, CD10 and bcl-6 in angioimmunoblastic T-cell lymphoma and peripheral T-cell lymphoma, not otherwise specified].

OBJECTIVE: To study the value of immunomarkers CXCL13, CD10, bcl-6 in pathologic diagnosis of angioimmunoblastic T-cell lymphoma (AITL). METHODS: One hundred and fifteen cases of AITL, 30 cases of peripheral T-cell lymphoma, not otherwise specified (PTCL, NOS) and 30 cases of reactive lymph nodes with paracortical hyperplasia (RH) encountered during the period from January, 1990 to January, 2008 were retrieved from the archival files of the Department of Pathology, West China Hospital of Sichuan University, China. The morphologic features were reviewed and compared. Immunohistochemical study was performed by SP method for CXCL13, CD10, bcl-6, CD21, CD3epsilon, CD3, CD45RO, CD20 and Ki-67. TCR-gamma gene rearrangement study was also carried out. RESULTS: Regressed follicles were evident in 7.8% (9/115) of AITL cases, 6.7% (2/30) of PTCL, NOS cases and 83.3% (25/30) of RH cases, respectively. A marked increase of number of arborizing venules was shown in 98.3% (113/115) of AITL cases, 63.3% (19/30) of PTCL, NOS cases and 76.7% (23/30) of RH cases, respectively. In lymph nodes with paracortical hyperplasia, the expression of CXCL13, CD10 and bcl-6 were restricted to the germinal centers. In AITL, 96.5% (111/115) of cases showed CXCL13 expression, in contrast to 26.7% (8/30) of PTCL, NOS. Expression of CD10 and bcl-6 were found in the neoplastic cells in 50.4% (58/115) and 78.3% (90/115) of AITL, and 3.3% (1/30) and 3.3% (1/30) of PTCL, NOS, respectively. Irregular meshworks of CD21-positive follicular dendritic cells were found in all the AITL cases. Clonal TCR-gamma rearrangement was detected in 83% (83/100) of the AITL cases. CONCLUSIONS: AITL is a type of lymphoma originated from the follicular helper T cells. Detailed morphologic assessment and use of immunohistochemical markers are essential for accurate diagnosis.

[Clinicopathologic features and diagnosis of 18 patients with angioimmunoblastic T-cell lymphoma].

OBJECTIVE: To explore the clinical and pathologic features of angioimmunoblastic T-cell lymphoma(AITL) and provide evidence for diagnosis. METHODS: Eighteen AITL patients (9 males and 9 females aged from 14 to 70 years) were retrospectively analyzed in Xiangya Hospital of Central South University from July 2002 to September 2007. RESULTS: Characteristic features at the presentation of AITL included generalized lymphadenopathy, fever, splenomegaly, and skin rashes with polyclonal hyper-gammaglobulinemia and other hematological abnormalities (such as Coombs-positive hemolytic anemia), which often involved the bone marrow and had well-described histologic features. The positive rate for CXCL13 was 93.3%. CONCLUSION: Repeated lymphadenbiopsy is helpful for AITL diagnosis. Routine histological and immunohistochemical examinations (especially including CXCL13) play significant role in the diagnosis and differential diagnosis of AITL.

TARC and IL-5 expression correlates with tissue eosinophilia in peripheral T-cell lymphomas.

The current study attempts to characterize the eosinophilia associated with T-cell lymphomas and to investigate its possible relationship with the secretion of eosinophil-stimulating factors by lymphoma cells and/or intra-tumoral surrounding cells. Paraffin-embedded specimens from 50 patients diagnosed with peripheral T-cell lymphomas, either unspecified (PTCL-U, n=30) or angioimmunoblastic (AITL, n=20) were morphologically assessed for intra-tumoral eosinophilia and analyzed by immunohistochemistry using specific antibodies directed against TARC, IL-5, RANTES, and eotaxin. The AITL and PTCL-U cases contained a mean of 147+/-41 and 102+/-37 eosinophils per 10 high power fields, respectively. Thirty-two of 47 cases (68%) showed IL-5-positive lymphoma cells while 15/50 (30%) tumors showed variable staining for TARC in scattered non-lymphoid cells with dendritic morphology. TARC and IL-5-positive cases possessed significantly more eosinophils. Our data indicate that IL-5 and TARC expression highly correlate with eosinophilia in T-cell lymphomas, suggesting that these chemokines are involved in the recruitment of eosinophils into the tumors.

[Clinicopathologic, immunohistochemical and molecular analysis in 15 cases of angioimmunoblastic T-cell lymphomas].

OBJECTIVE: To evaluate angioimmunoblastic T-cell lymphoma(AITL) completely, we gave injdepth investigation of histopathological features, specific immunochemical markers, antigen receptor gene rearrangements and in situ hybridization for Epstein-Barr virus (EBV). METHODS: 15 cases of typical AITL displayed effacement of the normal lymph node architecture partially or completely, abundance of arborizing high endothelial vessels, infiltration of polymorphic cells and hyperplastic atypical T lymphocytes with or without clear cytoplasm. Clinical characteristics, histological manifestations, and immunohistochemical staining for CD3, CD20, CD4ìCD21, CXCL13, CD10, and BCL6 were analyzed. Polymerase chain reaction for immunoglobulin heavy chain (IgH) and T cell receptor gamma (TCRgamma) rearrangements and in situ hybridization for Epstein-Barr virus encoded RNA (EBER-1) were performed. RESULTS: Histologically, we found eight cases with regressed lymphoid follicles, six with absence of follicles and one with hyperplastic follicles with interfollicular lesions. We also found eight cases displaying aggregation of clear cells, four infiltration of large lymphoid cells, five abundant epithelioid histiocytes. CD20 staining showed hyperplasia of large B cells in four cases. CD21 expression exihibited extrafollicular expansion of follicular dendritic cell meshworks in 11 cases (73.3%), partially with a tendency of perivascular distribution. Positive rate for CXCL13 and CD10 are 73.3% and 6.7% respectively. Monoclonal rearrangements of TCRgamma were detected in 6/15 (40%) of cases, IgH rearrangements in 7/15 (46.7%), of which five were monoclonal, while two oligoclonal. 8 out of 15 cases (53h3%) contained EBV-positive cells. Among the four cases with large B cell proliferation, three were EBV-positive. CONCLUSION: AITL display great complexity and diversity clinicopathologically. Only when we recognize such diversity, can we reasonably apply and properly evaluate immunochemical markers and molecular techniques, and thus give a correct diagnosis.