Anaplastic Kaposi sarcoma. A. Solid, haphazard proliferation of atypical spindled cells, with little evidence to suggest a vasoformative tumor (H&E stain). B. CD31 immunostain confirming the presence of a solid proliferation of atypical endothelial cells. C. LNA-1 immunostain for HHV-8 demonstrating positive immunoreactivity in the nuclei of several pleomorphic lesional cells.