Histopathology of the biopsy specimen. (A-B) Hematoxylin and eosin–stained biopsy specimen. (A) Small vessels are seen. (B) Infiltrating tingible-body macrophages contain only a few apoptotic bodies in the cytoplasm. Original magnification of objective lens ×10 (A) and ×40 (B). (C-H) IHC results for CD20 (C), SOX11 (D), Ki-67 (E), MYC (F), CCND1 (G) by rabbit SP4 (Nichirei Biosciences, Tokyo, Japan) and CCND1 (H) by mouse P2D11F11 (Leica Biosystems, Newcastle Upon Tyne, United Kingdom). Original magnification ×40. (G) Nuclei of histiocytes and endothelial cells were stained positive for the antibody.