A multicentric, malignant neoplastic vascular proliferation characterized by bluish-red cutaneous nodules, usually on the legs, toes, or feet, that slowly increase in size and number and spread to more proximal sites.

The tumors have endothelium-lined channels and vascular spaces mixed with aggregates of spindle-shaped cells; they may remain confined to skin and subcutaneous tissue, but widespread visceral involvement may occur.

Kaposi's sarcoma is endemic in certain parts of Central Africa and Central and Eastern Europe, and a virulent and disseminated form occurs in immunocompromised patients.