Background: BCL-6 is a proto-oncogene encoding a 95kDa Kruppel-type zinc finger protein with homology to other transcription factors. BCL-6 is expressed in normal follicular germinal center B cells and other related lymphomas. The expression of BCL-6 was detected in follicular lymphoma, diffuse large B-cell lymphoma, Burkitt's lymphoma and nodular lymphocytic Hodgkin's lymphoma. When splenic marginal zone lymphoma transformed into diffuse large B-cell lymphoma, BCL-6 expression was also detected in angioimmunoblastic T-cell lymphoma. In addition, it should be noted that many normal T cells also express BCL-6.