BCL-6 and BCL-2 expression in normal fetal thymus and T-LBL.

(A) Double staining for BCL-6 and BCL-2 in thymus. BCL-6⁺cells (nuclear, brown) were primarily present in the cortex, while BCL-2⁺ cells (cytoplasmic, blue) were primarily seen in the medulla. (B) Higher magnification showing that most cortical thymocytes expressing BCL-6 are BCL-2⁻. Only scattered cortical thymocytes are BCL-2⁺ and do not express BCL-6 (21 weeks gestational age). (C) Double staining for BCL-6 and BCL-2 in T-LBL (case No. 2) showing that neoplastic T lymphoblasts coexpress BCL-6 (nuclear, brown) and BCL-2 (cytoplasmic, blue). Original magnification × 100 (A), × 1000 (B), × 1000 (C).