VEGFR3/LYVE-1/Podoplanin lymphatic endothelial cells form the core of Kaposi Sarcoma; some are KS-herpesvirus-infected, many are not.

The lineage of the Kaposi Sarcoma (KS) tumor cell remains elusive to this day. Without that information, options for targeted therapy are limited. We applied concurrent, spatial imaging of six bona-fide lymphatic endothelial cell (EC) proteins to a well-curated collection of 30 HIV+ KS biopsies at true single-cell resolution (n = . Nodular KS had significantly more circular than elongated nuclei. Both types of KS had high-density clusters of LANA-positive cells: "LANA-nests." VEGFR-3 was the most highly expressed marker overall, although many VEGFR-3-positive cells were LANA negative. Podoplanin and LYVE-1 consistently colocalized with each other. CD31 and VE-Cadherin expression was variable within and across lesions. This data demonstrates multiple microenvironments within each KS lesion: LANA-dense nests, LANA-sparse fascicles, and differentiated lymphatic and blood vessels, where some of the lining cells were also LANA positive. Different targeted drugs would affect these differently. Thus, molecular parameters should be evaluated by within-tumor microenvironment type.