BCL-6 expression in T-LBL.

The percentage of BCL-6⁺ cells in T-LBL ranged from 50% to more than 90%. (A) Case No. 1. More than 90% of tumor cells, corresponding phenotypically to a double-positive (CD4⁺, CD8⁺) common thymocyte, show nuclear expression of BCL-6. (B) Double-staining for BCL-6 and CD3 in case No. 4, corresponding phenotypically to a double-negative (CD4⁻, CD8⁻) precursor thymocyte, shows that approximately 50% of the CD3⁺ malignant lymphoblasts (cytoplasmic, blue) express BCL-6 (nuclear, brown). Original magnification × 1000 (A), × 1000 (B).