Kaposi sarcoma (KS) is a vascular proliferation of lymphatic endothelial origin and associated with human herpesvirus 8 (HHV-8, Kaposi’s sarcoma-associated herpesvirus). It is commonly seen on the skin, but can affect several other organs.
Previously, it was seen mainly in elderly males of Jewish and Mediterranean extraction (classic endemic KS), but since the advent of HIV, it is is now an AIDS-defining disease (sometimes referred to as AIDS-related KS). Less commonly, it is seen in other forms of immunosuppression. There is debate on whether it is a neoplastic or reactive process.
Three stages: early patch stage, plaque stage and nodular stage.
It is characterised by a proliferation of atypical endothelial cell-lined, slit-like vascular spaces, often with a lymphocytic infiltrate. Immunohistochemistry against the HHV8 latent nuclear antigen-1 may help to confirm the diagnosis.