Immunophenotyping of angioimmunoblastic T-cell lymphomas by multiparameter flow cytometry.

Angioimmunoblastic T-cell lymphoma (AITL) is a distinct form of peripheral T-cell lymphoma (PTCL) frequently involving lymph nodes, spleen and bone marrow, and is associated with systemic symptoms. Its histologic features may be subtle at an early phase and difficult to diagnose. Despite the success of flow cytometry (FCM) in diagnosing B-cell neoplasm, FCM has not been widely accepted as a useful method for establishing the diagnosis of PTCL. Recently, the neoplastic T-cells in AITL have been shown to express CD10. We prospectively applied multiparameter FCM immunophenotyping to three cases of histologically confirmed AITL and identified a small (5-7%) population of CD4+/CD10+ T-cells in two cases. In one case, the CD4+/CD10+ population lacked surface signals of CD3 and CD7, but strongly expressed CD2, whereas CD45 expression was very weak; partial loss of surface CD3 was observed in the other. None of the lymph nodes with reactive hyperplasia, B-cell lymphomas, or Hodgkin's lymphoma studied during the same time period contained the CD4+/CD10+ population. These findings suggest that addition of CD4/CD10 and CD3/CD10 to FCM immunophenotyping panels is useful in the diagnosis of AITL. To the best of our knowledge, this is the first report to demonstrate CD10-expressing T-cells in AITL by FCM.