Our study assesses the utility of an immunohistochemical panel of 5 TFH markers (CD10, BCL6, PD-1, CXCL13, and ICOS) for identification of TFH phenotype in angioimmunoblastic T-cell lymphoma (AITL) and PTCL not otherwise specified (NOS).
We studied a series of 98 n-PTCL samples (comprising 57 AITL and 41 PTCL-NOS) with five T<sub>FH</sub> antibodies (CD10, BCL-6, PD-1, CXCL13, ICOS), looked for mutations in five of the genes most frequently mutated in AITL (<i>TET2</i>, <i>DNMT3A, IDH2, RHOA</i> and <i>PLCG1</i>) using the Next-Generation-Sequencing Ion Torrent platform, and measured the correlations of these characteristics with morphology and clinical features.
Reexamination and immunohistochemical staining of the previously biopsied lymph node specimen revealed the same clonal population of T cells positive for CD3, CD4, CD10, and programmed cell death protein 1 (PD-1) that was present in the skin and confirmed a diagnosis of AITL.
Angioimmunoblastic T-cell lymphoma (AITL) has increased neoplastic follicular-helper T cells (FHT), which often express CD10; but nonneoplastic, CD10-positive T cells may be associated with reactive lymphadenopathy and with B-cell lymphomas.
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].
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).
Our data show that aberrant CD10 expression is a useful phenotypic marker for diagnosis of AITL in most involved extranodal sites, except bone marrow, and suggest a possible role of FDC in the pathogenesis of AITL.