What is Kaposi sarcoma (KS)?

Updated: Apr 11, 2019
  • Author: Jessica Katz, MD, PhD, FACP; Chief Editor: Edwin Choy, MD, PhD  more...
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Answer

Kaposi sarcoma (KS) is an indolent angio-proliferative spindle-cell tumor derived from endothelial and immune cells infected with human herpes virus type 8 (HHV-8; also known as Kaposi sarcoma herpes virus [KSHV]). HHV-8 is identified as the causative agent of KS; it is present in 95-98% of all cases. [1] KS is categorized into the following 4 types [2] :

  • Epidemic (AIDS related)
  • Iatrogenic (immunosuppressant therapy related)
  • Classic, or sporadic
  • Endemic (African)

Increasing reports describe cases of KS in men who have sex with men but who have no evidence of HIV infection or immunodeficiency. These cases present in an indolent cutaneous form that resembles classic KS, and have been regarded as a fifth type of KS, termed nonepidemic KS. [3, 4, 5]

Although all types of KS have in common infection with HHV-8, each has a distinct clinical course. Therefore, it is likely that other factors, such as extent and type of immune suppression, influence the disease. [6] The presentation of KS ranges from minimal mucocutaneous disease to extensive organ involvement.

The epidemiology of KS has changed dramatically from 1872, when it was first described as a rare disease in Eastern European men. In the 1950s, an endemic form of KS was reported to be one of the most common neoplasms observed in central Africa, affecting men, women, and children. The cases in children are due to maternal-child transmission of HHV-8 through saliva. [6]  

A surge in KS cases was noted just prior to the identification of the AIDS epidemic in the early 1980s. AIDS-related KS is the most common KS presentation in the United States. Estimates indicate that the risk of KS in people living with HIV from 2009-2012 was 500-fold higher than for the US general population. KS accounts for 12% of cancers in people living with HIV, with 765 to 910 new cases per year in the US. [7, 8, 9]

Notably, following the AIDS epidemic, the incidence of KS in Africa increased markedly. From 1968 to 1970, KS accounted for 6.6% of all cancers occurring in men; however, from 1989 to 1991, KS became the most commonly reported cancer in men. [10, 11]

Iatrogenic KS cases have also increased, due to greater use of immunosuppression in medical practice. These include the post-transplant setting and treatment of autoimmune disease. [9]


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