KSHV-associated MCD. KSHV-positive plasmablasts express monotypic λ light chain, IgM, CD19, and MYC; plasmablasts are also positive for CD38, CD45, and CD79a and are usually negative for CD10, CD20, CD30, CD138, BCL6, PAX5, T-cell antigens, and EBV infection (data not shown). A schematic lymphoid follicle in KSHV-associated MCD is depicted at the center. The follicle mantle zone (MZ) is typically rich in small mantle lymphocytes that are mixed with plasmablasts. These latter cells are also found at the boundary between the GC and the MZ. Vascular transformation of the GC is also depicted. Vascular GC is observed in KSHV-associated MCD as shown in the microphotograph placed on the left in the figure. As shown on the right in the figure, large cells with plasmablastic features are positive for MUM1/IRF4, λ light chain, ORF73/LANA encoded by KSHV, and viral IL6. MUM1, λ light chain, ORF73/LANA, v-IL6, immunohistochemistry, hematoxylin counterstain. Original magnification, ×200 (H&E on the left), ×1000 (H&E on the left), and ×400 (other images). Images were taken using a Nikon Eclipse 80i microscope with Plan Fluor 20×/0.75, Plan Fluor 40×/0.75, and Plan Apo/1.40 oil objectives and Nikon digital sight DS-Fi1 camera equipped with control unit-DS-L2. Images were processed using Adobe Photoshop CS2 V9.0.