Large B-cell lymphoma centroblasts are BMI-1⁺/EZH2⁺ that coexpress MIB1⁺.

(A-C, first row) Immunohistochemistry (IHC) of large B-cell lymphoma with numerous centroblasts shows clear expression of BMI-1 (A), EZH2 (B), and Mib-1/Ki67 (C). Large brown-staining cells are positive. Small lymphocytes also stain for BMI-1 (A), whereas these cells are negative for EZH2 and Mib-1/Ki-67. Photographs are taken from different parts of the tumor. One representative example is shown. Original magnification, 63× objective. (D-F, second row) Immunofluorescence (IF) of large B-cell lymphoma shows red staining for BMI-1 (D), green staining for EZH2 (E), and overlay photographic exposure with yellow cells indicative of centroblasts expressing both BMI-1 and EZH2 (F). Note that bright BMI-1⁺ (red) cells are probably macrophages (MΦ), as indicated in panels D and F. Note that small (infiltrating) lymphocytes in panels D to F show expression of BMI-1 but not of EZH2, as expected. (G-I, third row) IF of large B-cell lymphoma shows expression of Mib/Ki67 in red (G) and EZH2 in green (H). Double fluorescence confirms the coexpression of these proteins in the nuclei of tumor cells (J, overlay photographic exposure with yellow nuclei). Same example as in panels D to F is shown in panels G to I. All IF pictures were taken with 63× objective.