AIDS-related systemic NHLs. (A through C) AIDS-LNCCL displaying the BCL-6⁺ (A), CD138/syndecan-1 (syn-1)⁻ (B), LMP-1⁻ (C) phenotype. (A) Large tumor cells show a nuclear staining pattern with anti–BCL-6 MoAb. (B) A residual plasma cell shows cytoplasmic staining for anti–syn-1 MoAb. (C) No LMP-1 expression is detectable. (D through F) AIDS-IBLP displaying the BCL-6⁻ (D), syn-1⁺ (E), LMP-1⁺ (F) phenotype. (D) No BCL-6 expression is detectable. (E) Most immunoblastic-plasmacytoid tumor cells show strong cytoplasmic immunoreactivity with the anti–syn-1 MoAb. (E inset) A higher-power photograph showing the cytoplasmic staining pattern on large immunoblasts-plasmacytoid. (F) LMP-1 positivity is manifested as cytoplasmic or membrane staining on several large tumor cells displaying immunoblastic-plasmacytoid morphology. (G through I) AIDS-SNCCL displaying the BCL-6⁺ (G), syn-1⁻ (H), LMP-1⁻ (I) phenotype. (G) Most neoplastic cells show strong nuclear immunoreactivity with the anti–BCL-6 MoAb. (H) A residual plasma cell shows cytoplasmic staining for anti–syn-1 MoAb. (I) No LMP-1 expression is detectable. APAAP immunostaining; (A), (D), (G) frozen section; (B), (C), (E), (E inset), (F), (H), (I) paraffin-embedded tissue section, hematoxylin counterstain. Original magnification ×250 (A through I).