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.
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.
ITK-SYK transcripts were detected in five of 30 (17%) unspecified PTCL, but not in cases of angioimmunoblastic T-cell lymphoma (n=9) and anaplastic lymphoma kinase-negative anaplastic large-cell lymphoma (n=7).
Notably, we found that the vascular endothelial growth factor (VEGF) was expressed not only by reactive cells, but also by neoplastic cells, and that nuclear factor-kappaB (NF-kappaB) activation is uncommon in AILT, as suggested by frequent exclusively cytoplasmic c-REL localization.
Double immunostaining in AILT revealed that the majority of c-Maf-positive cells were also positive for CD43 (MT1), CD45RO (UCHL-1), and CD4 but were negative for CD20 (L26).
Recently, genome-wide approaches have suggested follicular CD4 T-helper cells (T(H)F) as additional CXCL13 producers in the germinal centre and the neoplastic counterpart of T(H)F (CD4+ tumour T-cells in angioimmunoblastic T-cell lymphoma) retains the capability of producing this chemokine.
Angioimmunoblastic T-cell lymphoma (AITL) comprises CD4+ CXCL13+ neoplastic cells displaying overlapping immunophenotypical and molecular features with normal follicular helper T cells.
Moreover, significantly higher Ang1 and Tie2 expression was detected in AILT cases with CD10-positive neoplastic T-cells by comparison with unspecified peripheral T-cell lymphoma (14 cases).
Angiogenic mediators angiopoietin (Ang) 1 (ANGPT1), Ang2 (ANGPT2) and their receptor, Tie2 (TEK), vascular endothelial growth factor (VEGF; VEGFA) and its receptor, VEGFR2 (KDR), and hepatocyte growth factor (HGF) and its receptor, c-Met (MET) were all more highly expressed in AILT lymph nodes (16 cases) than in B-cell lymphomas (24 cases).
The detection of clonal T cell receptor (TCR) gene rearrangements helps in the diagnosis of T cell malignancies such as AILT, where morphological and immunohistological investigations are not always sufficient to reach a definitive diagnosis.
Angiogenic mediators angiopoietin (Ang) 1 (ANGPT1), Ang2 (ANGPT2) and their receptor, Tie2 (TEK), vascular endothelial growth factor (VEGF; VEGFA) and its receptor, VEGFR2 (KDR), and hepatocyte growth factor (HGF) and its receptor, c-Met (MET) were all more highly expressed in AILT lymph nodes (16 cases) than in B-cell lymphomas (24 cases).
Angiogenic mediators angiopoietin (Ang) 1 (ANGPT1), Ang2 (ANGPT2) and their receptor, Tie2 (TEK), vascular endothelial growth factor (VEGF; VEGFA) and its receptor, VEGFR2 (KDR), and hepatocyte growth factor (HGF) and its receptor, c-Met (MET) were all more highly expressed in AILT lymph nodes (16 cases) than in B-cell lymphomas (24 cases).
Angiogenic mediators angiopoietin (Ang) 1 (ANGPT1), Ang2 (ANGPT2) and their receptor, Tie2 (TEK), vascular endothelial growth factor (VEGF; VEGFA) and its receptor, VEGFR2 (KDR), and hepatocyte growth factor (HGF) and its receptor, c-Met (MET) were all more highly expressed in AILT lymph nodes (16 cases) than in B-cell lymphomas (24 cases).
Moreover, significantly higher Ang1 and Tie2 expression was detected in AILT cases with CD10-positive neoplastic T-cells by comparison with unspecified peripheral T-cell lymphoma (14 cases).
Angiogenic mediators angiopoietin (Ang) 1 (ANGPT1), Ang2 (ANGPT2) and their receptor, Tie2 (TEK), vascular endothelial growth factor (VEGF; VEGFA) and its receptor, VEGFR2 (KDR), and hepatocyte growth factor (HGF) and its receptor, c-Met (MET) were all more highly expressed in AILT lymph nodes (16 cases) than in B-cell lymphomas (24 cases).
9p24 gains were detected in 6/17 (35%) primary mediastinal B-cell lymphomas (PMBCLs), 25/77 (33%) Hodgkin's lymphomas (HLs), 3/16 (19%) angioimmunoblastic T-cell lymphomas (AILTs) and 1/5 ALK1(+) anaplastic large cell lymphomas (ALCLs); breaks were observed only in three cases. pJAK2 expression was most prevalent in PMBCL, peripheral T-cell lymphomas and HL. pSTAT3 predominated in ALCLs, HLs, AILTs, PMBCLs and peripheral T-cell lymphomas. pSTAT5 expression was detected frequently in follicular lymphomas, diffuse large B-cell lymphomas and AILTs.
9p24 gains were detected in 6/17 (35%) primary mediastinal B-cell lymphomas (PMBCLs), 25/77 (33%) Hodgkin's lymphomas (HLs), 3/16 (19%) angioimmunoblastic T-cell lymphomas (AILTs) and 1/5 ALK1(+) anaplastic large cell lymphomas (ALCLs); breaks were observed only in three cases. pJAK2 expression was most prevalent in PMBCL, peripheral T-cell lymphomas and HL. pSTAT3 predominated in ALCLs, HLs, AILTs, PMBCLs and peripheral T-cell lymphomas. pSTAT5 expression was detected frequently in follicular lymphomas, diffuse large B-cell lymphomas and AILTs.
The recent identification of follicular helper T (T(FH)) cell as the cell of origin of this neoplasm represents a major step in our understanding of the pathobiological characteristics of the disease and should, in the future, clarify the diagnostic criteria for AITL and help to delineate its spectrum, especially from PTCL, not otherwise specified (PTCL, NOS).
The recent identification of follicular helper T (T(FH)) cell as the cell of origin of this neoplasm represents a major step in our understanding of the pathobiological characteristics of the disease and should, in the future, clarify the diagnostic criteria for AITL and help to delineate its spectrum, especially from PTCL, not otherwise specified (PTCL, NOS).
Gene expression profiling was performed on 144 cases of PTCL and natural killer cell lymphoma and robust molecular classifiers were constructed for angioimmunoblastic T-cell lymphoma (AITL), anaplastic lymphoma kinase-positive (ALK(+)) anaplastic large-cell lymphoma (ALCL), and adult T-cell leukemia/lymphoma.