Microscopic morphology of representative lymph node sections and immunohistochemical detection of KSHV infection.

(A) Small hyalinized germinal center surrounded by concentric layers of small lymphocytes (hematoxylin and eosin stain; × 100). (B) Interfollicular sheets of plasma cells are shown (hematoxylin and eosin stain; × 1000). (C) KSHV-LANA antigen detection in the lymph node mantle zone visualized by immunohistochemical staining with monoclonal antibody (× 200). The inset shows the characteristic speckled nuclear pattern (× 1000). (D) vIL-6 detection in immunoblastic cells in the lymph node mantle zone (× 100). The insets show specific cytoplasmic staining (× 1000).