Cases 8 and 10.

(A-E): Case 8. Follicle and interfollicular plasma cells stained (A) for HHV-8, (B) for μ heavy chain, (C) for κ light chain, (D) for λ light chain, and (E) with Ki-67. The mantle zone plasmablasts show nuclear positivity for HHV-8, express μ heavy chain, and show λ light-chain restriction, while the μ negative interfollicular plasma cells are polytypic with respect to light chains. Most, if not all, of the plasmablasts are in cycle. (F) Case 10. Mantle zone immunoblasts double-stained for HHV-8 (blue) and λ light chain (brown). HHV-8–positive nuclei are exclusively within λ-positive cells.