RESUMO
<p><b>OBJECTIVE</b>To study the value of immunomarkers CXCL13, CD10, bcl-6 in pathologic diagnosis of angioimmunoblastic T-cell lymphoma (AITL).</p><p><b>METHODS</b>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.</p><p><b>RESULTS</b>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.</p><p><b>CONCLUSIONS</b>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.</p>