Kaposi Sarcoma

(Kaposi's Sarcoma; Multiple Idiopathic Hemorrhagic Sarcoma)

ByVinod E. Nambudiri, MD, MBA, EdM, Harvard Medical School
Reviewed/Revised Dec 2023
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Kaposi sarcoma is a multicentric vascular tumor caused by herpesvirus type 8. It is categorized into 5 types: classic (sporadic), AIDS-associated (epidemic), non-epidemic, endemic (in Africa), and iatrogenic (eg, after organ transplantation). Diagnosis is by biopsy. Treatment for indolent superficial lesions involves cryotherapy, electrocoagulation, excision, or electron beam radiation therapy. Radiation therapy is used for more extensive disease. In the AIDS-associated form, treatment includes antiretrovirals.

(See also Overview of Skin Cancer.)

Kaposi sarcoma originates from endothelial cells in response to infection by human herpesvirus type 8 (HHV-8). Immunosuppression (particularly due to organ transplantation or AIDS) markedly increases the likelihood of Kaposi sarcoma in patients infected with HHV-8.

The tumor cells have a spindle shape, resembling smooth muscle cells, fibroblasts, and myofibroblasts.

Classification of Kaposi Sarcoma

Classic Kaposi sarcoma

This type occurs most often in older (> 60 years) men of Mediterranean, Eastern European, or Ashkenazi Jewish ancestry.

The course is indolent, and the disease is usually confined to a small number of lesions on the skin of the lower extremities; visceral involvement occurs in < 10%.

This type is usually not fatal.

Kaposi Sarcoma (Classic Type)
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In classic Kaposi sarcoma, cutaneous lesions are asymptomatic purple, pink, or red macules that may coalesce into blue-violet to black plaques and nodules.
Photo provided by Thomas Habif, MD.
Kaposi Sarcoma (Classic Type)
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This photo shows a classic reddish purple vascular lesion of Kaposi sarcoma.
Photo courtesy of Karen McKoy, MD.

AIDS-associated Kaposi sarcoma (epidemic Kaposi sarcoma)

This type is the most common AIDS-associated cancer and is more aggressive than classic Kaposi sarcoma.

Multiple cutaneous lesions are typically present, often involving the face and trunk. Mucosal, lymph node, and gastrointestinal (GI) involvement is common. Sometimes Kaposi sarcoma is the first manifestation of AIDS.

Kaposi Sarcoma (AIDS-Associated Type)
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AIDS-associated Kaposi sarcoma is an aggressive, multicentric tumor that may involve the face, trunk, mucosal surfaces, lymphatics, or gastrointestinal tract. Lesions appear as bluish to violaceous macules, plaques, or tumors.
Photo courtesy of Sol Silverman, Jr., via the Public Health Image Library of the Centers for Disease Control and Prevention.

Non-epidemic Kaposi sarcoma

An additional type of Kaposi sarcoma that has been increasingly recognized occurs in men who are HIV-negative and who have sex with men (1). The reasons for increased prevalence in this group is uncertain and remains an area of ongoing investigation.

Endemic Kaposi sarcoma

This type occurs in Africa independent of HIV infection. There are 2 main forms:

  • Prepubertal lymphadenopathic form: It predominantly affects children; primary tumors involve lymph nodes, with or without skin lesions. The course is usually fulminant and fatal.

  • Adult form: This form resembles classic Kaposi sarcoma.

Iatrogenic Kaposi sarcoma (immunosuppressive Kaposi sarcoma)

This type typically develops several years after organ transplantation. The course is more or less fulminant, depending on the degree of immunosuppression.

Classification reference

  1. 1. Vangipuram R, Tyring SK: Epidemiology of Kaposi sarcoma: review and description of the nonepidemic variant. Int J Dermatol 58(5):538-542, 2019. doi: 10.1111/ijd.14080

Symptoms and Signs of Kaposi Sarcoma

Cutaneous lesions are asymptomatic purple, pink, brown, or red macules that may coalesce into blue-violet to black plaques and nodules. Some edema may be present. Occasionally, nodules fungate or penetrate soft tissue and invade bone.

Although less common, visceral involvement most often involves the oral cavity, gastrointestinal (GI) tract, and the lungs. Symptoms depend on specific organ involvement. Mucosal lesions appear as bluish to violaceous macules, plaques, and tumors. GI lesions can bleed, sometimes extensively, but usually are asymptomatic.

Diagnosis of Kaposi Sarcoma

  • Biopsy

Diagnosis of Kaposi sarcoma is confirmed by punch biopsy.

Patients with AIDS or immunosuppression require evaluation for visceral spread by CT of the chest and abdomen.

If CT is negative but pulmonary or GI symptoms are present, bronchoscopy or endoscopy should be considered.

Treatment of Kaposi Sarcoma

  • Surgical excision, cryotherapy, electrocoagulation, intralesional chemotherapy, or possibly topical imiquimod or alitretinoin for superficial lesions

  • Local radiation therapy and chemotherapy for multiple lesions, diffuse involvement, or lymph node disease

  • Antiretroviral therapy with similar local treatments or chemotherapy depending on extent of disease for AIDS-associated Kaposi sarcoma

  • Reduction of immunosuppressants for iatrogenic Kaposi sarcoma

Treatments for classic Kaposi sarcoma and AIDS-associated Kaposi sarcoma overlap considerably.

AIDS-associated Kaposi sarcoma responds markedly to antiretroviral therapy (ART), probably because the CD4+ count increases and the HIV viral load decreases; however, there is some evidence that protease inhibitors in this regimen may block angiogenesis (although this has not been shown to have beneficial clinical effects in humans).

In patients with AIDS who have indolent local disease, CD4+ counts > 150/mcL, and HIV RNA <

2doxorubicin fails.

Other agents being investigated as adjuncts include interleukin (IL)-12, desferrioxamine, and oral retinoids. Treatment of Kaposi sarcoma does not prolong life in most patients with AIDS because infections dominate the clinical course.

Non-epidemic classic Kaposi sarcoma requires treatment of indolent lesions as described above.

Iatrogenic Kaposi sarcoma

Endemic Kaposi sarcoma treatment is challenging and typically palliative.

Key Points

  • Consider Kaposi sarcoma in older men, Africans, and patients with organ transplants or AIDS.

  • Test patients with immunosuppression (including AIDS) for metastases.

  • Treat superficial lesions with locally ablative methods.

  • Treat multiple lesions, diffuse involvement, or lymph node disease with local radiation therapy and chemotherapy.

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