(A through C) Morphology and proliferation index of 1 case of plasmablastic lymphoma. (A) Giemsa staining, original magnification × 400. (B) Giemsa staining, original magnification × 800. (C) Staining with the Ki-67–specific antibody MIB-1. (D through F ) Paraffin sections of lymph nodes from patients with large-cell lymphomas stained for B-cell–specific antigens. (D) Large-cell lymphoma of the common type, L26 antibody, strong membrane staining in all cells. (E) Plasmablastic lymphoma, strong staining for CD79a (JCB117). (F ) Plasmablastic lymphoma, with an unusually high number of cells showing membranous staining with the L26 antibody. (G) Paraffin section from a plasmablastic lymphoma. Intense staining for IgG. (H) Paraffin section from a plasmablastic lymphoma. All neoplastic cells are strongly labeled by the antibody VS38c. (I through K) Association of plasmablastic lymphomas with EBV and expression of viral latent proteins. (I) In situ hybridization for EBER transcripts. (J) Immunostaining with an antibody specific to the viral BZLF-1 protein. (K) Immunostaining with an antibody specific to viral LMP-1.