Kaposi sarcoma

Author: Dr Jane Morgan, Sexual Health Physician, Waikato Hospital, Hamilton, New Zealand, 2003. Latest update by Jannet Gomez; Dr Amanda Oakley, February 2017.

What is Kaposi sarcoma?

Kaposi sarcoma (KS) is a disease of blood vessels the lining of blood vessels and lymphatics. It was considered very rare before the start of the AIDS pandemic. AIDS is due to infection with human immunodeficiency virus (HIV).

There are four types of Kaposi sarcoma.

  1. The classic type of Kaposi sarcoma affects elderly men of Mediterranean and Middle European descent and in men in Sub-Saharan Africa.
  2. HIV-associated Kaposi sarcoma mainly affects men who have sex with men.
  3. Endemic or African Kaposi sarcoma arises in some parts of Africa in children and young adults.
  4. Iatrogenic Kaposi sarcoma is due to drug treatment causing immune suppression.

Classic Kaposi sarcoma is rare and unassociated with HIV infection. It most often arises in middle-aged to elderly men of Mediterranean or Jewish descent (less than 10% are women), particularly if they come from a rural environment. They have a higher than expected rate of diabetes mellitus.

In the United States, Kaposi sarcoma was particularly common in the 1980s especially amongst HIV-positive men who had sex with men, in which it has a very aggressive course. It occurs less frequently in intravenous drug users and is rare in women, haemophiliacs or their sexual partners. HIV-associated Kaposi sarcoma is more common in women in some parts of Africa. It has become less common in the US and Europe because of effective HAART treatment for HIV disease.

African Kaposi sarcoma is becoming more prevalent with the rise in HIV infection. It is one of the most common forms of cancer, especially in children, in Uganda and Zambia.

Iatrogenic Kaposi sarcoma is a particular concern for organ transplant patients, especially in geographic areas associated with high levels of infection with KSHV. Most have the virus prior to transplantation, but the drugs causes it to reactivate. Use of corticosteroids and biologics like rituximab, infliximab, and abatacept, prescribed  for chronic inflammatory and autoimmune conditions, are also  prone to develop Kaposi sarcoma.

What is the cause of Kaposi sarcoma?

Kaposi sarcoma is associated with:

Kaposi sarcoma is a multicentric, ie, it appears on more than one part of the body at once. It is a reactive hyperplasia rather than a neoplasm (cancer). Despite its name, it is no longer classified as a sarcoma (malignant tumour of mesenchymal origin).

KSHV may lie dormant, or replicate and cause disease. As well as causing Kaposi sarcoma, it may also be the cause of some forms of non-Hodgkin lymphoma and Castelman disease.

How does Kaposi sarcoma present?

Kaposi sarcoma presents as red to purplish macules, papules and nodules anywhere on the skin or mucous membranes lining the mouth, nose, and throat; lymph nodes; or other organs. Initially, the lesions are small and painless but they can ulcerate and become painful. There are various forms.

Kaposi sarcoma often starts as flat patches one or both lower legs, often in association with lymphoedema. The patches evolve into plaques, nodule or scaly tumours.

Kaposi sarcoma in association with HIV infection may develop at any time during the course of illness. Generally, the greater the immunosuppression (e.g. with CD4 cell counts less than 200/mm3) the more extensive and aggressive the Kaposi sarcoma will be.

Kaposi sarcoma lesions can also occur internally; in the gut, lungs, genitals, lymphatic system and elsewhere. These internal lesions may cause symptoms, eg, discomfort with swallowing, bleeding, haematemesis, haematochezia, melaena, bowel obstruction, shortness of breath, swollen legs, etc.

See more images of Kaposi sarcoma ...

Diagnosis of Kaposi sarcoma

Blood tests may show no abnormality, depending whether there are associated disorders such as AIDS. Anaemia may arise if there is bleeding. KSHS assays or antibody titres to KSHS are difficult to interpret. CD4 lymphocyte counts and plasma HIV load studies are performed in patients with HIV infection.

The appearance of Kaposi sarcoma lesions is often typical but a skin biopsy of a lesion allows a definite diagnosis, as various lesions such as melanoma, fungal infections, and mycetoma mimic Kaposi sarcoma  in appearance and location. Histopathology shows red cells in slit-like spaces formed by atypical spindle cell proliferation of endothelial cells and associated with inflammatory cells.

Staging and prognosis in Kaposi sarcoma

There have been various attempts to classify Kaposi sarcoma, depending on whether it is localised or disseminated in the skin, and if there is lymph node or internal organ involvement. The degree of immunosuppression present may also be used in staging systems.

Kaposi sarcoma has a variable course. Some patients develop only a few minor skin lesions whilst others have much more extensive external and internal disease. The latter lesions may result in fatal complications, e.g., from bleeding, obstruction or perforation of an organ. Kaposi sarcoma is not curable, but it can be treated and its symptoms controlled.

Treatment of Kaposi sarcoma

In HIV disease, if the lesions are not widespread or troublesome, often the best approach is simply to treat the underlying HIV infection with highly active antiretroviral drug combinations that suppress HIV replication (HAART).

Iatrogenic Kaposi sarcoma may improve or clear if it is possible to stop immune suppressive medication.

The choice of more specific treatment depends largely on the extent of the disease.

Treating localised lesions

Small, localised lesions are generally only treated if they are painful or they are causing cosmetic problems. It should be noted that lesions tend to recur after local treatments. Treatments include:

Treating extensive or internal lesions with systemic therapy

A combination of anti-cancer drugs are given, but at lower than usual dosages if there is immunosuppression.

Other chemotherapy treatments that are used in some international centres include bleomycin, etoposide, paclitaxel, docetaxel and liposomal forms of the standard anti-cancer drugs, doxorubicin or daunorubicin. Liposomal means that the drugs are coated in small fat bubbles, or liposomes, which allows better absorption, resulting in less cardiac toxicity and myelotoxicity. Paclitaxel is approved for use in Kaposi sarcoma in advanced stages or as a second-line option.

Immunotherapy includes the use of interferon-alpha and imiquimod, sirolimus and thalidomide

Kaposi sarcoma may arise in organ transplant patients. Switching from ciclosporin to sirolimus (rapamycin) has resulted in resolution of the sarcoma. This is largely attributed to the anti-proliferative and anti-angiogenic effects of sirolimus (mTor inhibitor).

Clinical trials into a wide range of other therapies are ongoing. 

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