OBJECTIVETo 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.

METHODSImmunohistochemical 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.

RESULTSAmongst 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.

CONCLUSIONSAs 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.