Treatment of classical Kaposi's sarcoma with intralesional injections of cidofovir: report of a case.

The effect of intralesional injections of cidofovir, a nucleotide analog with potent in vitro activity against human herpesvirus 8 (HHV-8), was studied in vivo in an HIV-negative patient with classical Kaposi's sarcoma (KS). After five weekly injections of the drug, no clinical, histological, immunohistological, or virological changes could be detected in comparison with saline-injected lesions. These findings suggest that, once the KS tumor has developed, active viral replication is no longer involved in the pathogenesis of the disease. Alternative hypotheses are that HHV-8 replication in blood-borne cells may foster growth of spindle cells in the skin, or that blocking HHV-8 may not affect existing lesions but may prevent new lesions from developing.