Case 186. Kaposi sarcoma in AIDS (43 y-o M)
    Multiple hemorrhagic skin nodules on the trunk and extremities (biopsy from the arm lesion)    
Key words : human herpes virus type 8, Kaposi sarcoma
opportunistic infection
Increase of capillary vessels with swelling of endothelial cells, nuclear atypia, hemosiderosis and hyaline globular inclusions in the cytoplasm are observed (HE).   Higher powered view demonstrates swollen endothelial cells with prominent nucleoli and PAS reactivity of the hyaline globules (PAS).
Reference case 186A
Kaposi sarcoma in an HIV-negative 68 y-o male (biopsy from the facial lesion, HE). Proliferation of atypical polygonal cells is noted in the lesion. Lumen formation is focally discerned (HE). HHV-8 etiology is also indicated in the non-HIV cases.
  Reference case 186A
Immunostaining for factor VIII-related antigen (von Willebrand factor), demonstrating positivity in the tumor cells. Most of the proliferating cells express the endothelial marker, confirming the endothelial origin of the tumor cells. Multifocal and multiorgan involvement of Kaposi sarcoma was seen at autopsy.
Human herpes virus 8 in cultured TY-1 cells
A cultured cell line established from primary diffusion lymphoma expresses HHV-8 genome in the nucleus (in situ hybridization using a probe for HHV terminal repeat). HHV-8, or Koposi sarcoma herpes virus (KSHV), is shown to be a causative agent not only for Kaposi sarcoma, but also a special form of B-cell lymphoma, primary effusion lymphoma. Multicentric Castleman's disease in AIDS is also caused by this oncogenic DNA virus.