Kaposi sarcoma (KS) is a rare neoplasm that shows sporadic, endemic, and epidemic forms. KS usually presents with purplish papular cutaneous lesions often on the lower limbs, back, and mouth, but may also involve the gastrointestinal and respiratory systems. KS is caused by an infectious agent, Kaposi sarcoma-associated herpesvirus (KSHV; human herpesvirus-8, HHV-8). KSHV infection is necessary but not sufficient for KS development; the infection is mostly asymptomatic but may cause disease in immunocompromised patients (summary by Yogev et al., 2024).
KS is an invasive angioproliferative inflammatory condition that occurs commonly in men infected with human immunodeficiency virus (HIV; see 609423). In the early stages of KS, lesions appear reactive and are stimulated to grow by the actions of inflammatory cytokines and growth factors. In the late stages of KS, a malignant phenotype that appears to be monoclonal can develop. Coinfection with HIV markedly increases the likelihood of KS development, and additional environmental, hormonal, and genetic cofactors likely contribute to its pathogenesis (summary by Foster et al., 2000).
Suthaus et al. (2012) noted that HHV-8 is the etiologic agent not only of KS, but also of primary effusion lymphoma and plasma cell-type multicentric Castleman disease (MCD). [from
OMIM]