The goal of this study is to determine whether intra-lesional injections of nivolumab can enhance specific T cell responses in vitro and enhance activity against these virus-associated lesions. Chronic viral infections generate "exhausted" CD8+ T cells with a diminished capacity to produce cytokines and to lyse infected cells. The PD-1/PD-L1 pathway implicated in the balance between immune eradication and immune escape. This study will evaluate the safety, tolerability, and potential benefits of injecting nivolumab into KS in HIV-infected and HIV-uninfected individuals every 2 weeks for total of 4 doses. The investigators believe this mode of treatment is feasible and tolerable by avoiding the systemic autoimmune adverse events caused by systemic injection of nivolumab.