Apoptosis, Bcl-2 expression, and cell proliferation. The left panel shows a case of Burkitt lymphoma, characterized by extensive apoptosis, which creates a “starry sky” appearance due to phagocytosis of cell debris by the macrophages in H.E staining. Notably, Bcl-2 is not expressed, and the tumor proliferation index is extremely high. The right panel depicts a case of low-grade follicular lymphoma (FCL), in which apoptosis is rarely observed. Bcl-2 expression is abnormally high due to its dislocation to the neighborhood of immunoglobulin heavy chain (IgH), resulting in a significantly lower tumor proliferation index. All the pictures are the same magnification. Bar = 60 µm.