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

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).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.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.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.