Kaposi sarcoma (KS) is a rare cancer that can cause skin lesions on a person’s feet. The lesions may appear as purple, reddish-blue, or brown marks on the skin, and people may mistake them for other conditions.

KS causes tumors or lesions on the skin or internal organs. These tumors can cause serious problems or become fatal if left untreated. However, KS skin lesions can also have no symptoms.

KS has four forms, all caused by the herpes virus, specifically human herpesvirus 8 (HHV 8). KS most commonly appears in people with immunosuppression. This includes people with AIDS or those undergoing immunosuppression due to organ transplants.

Read on to learn about Kaposi sarcoma lesions on the feet, other places where lesions may appear, causes, treatment, and typical questions about the condition.

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KS can cause lesions on the feet. KS skin lesions can appear on any part of the body, but they are more likely to appear in the lower extremities.

This can include a person’s:

  • legs
  • ankles
  • soles of the feet

These skin lesions usually cause no symptoms, but some may cause painful foot swelling, ulceration, or even bleeding.

KS skin lesions look like purple, reddish-blue, or brown marks on the skin. They can appear as macules (flat discolored areas of skin), papules (raised pimple-like growths), or nodules (lumps under the skin).

A type of KS called “classic Kaposi sarcoma” tends to produce small macules and nodules confined to the lower parts of the body. They multiply and extend beyond these areas as the condition progresses.

KS can cause skin lesions to appear on other parts of the body. This includes a person’s:

  • arms
  • face
  • neck
  • groin
  • legs
  • skin
  • the lining of the mouth
  • genitals

Lesions are more likely to appear on the lower body parts. It is also possible for no lesions to form with KS.

KS lesions can also appear in internal parts of the body, including:

  • lymph nodes
  • stomach
  • intestines
  • lungs
  • liver
  • spleen
  • kidneys

A note about sex and gender

Sex and gender exist on spectrums. This article will use the terms “male,” “female,” or both to refer to sex assigned at birth. Click here to learn more.

HHV 8, also known as Kaposi sarcoma-associated herpesvirus (KSHV), causes all types of Kaposi sarcoma. This virus transmits mainly via saliva during sexual interaction.

KS can also pass from pregnant person to fetus during pregnancy. KS is generally more common in males.

There are four recognized types of KS:

  • Classic KS: This primarily affects the skin on the legs and feet. Classic KS mainly occurs in older men of Jewish or Mediterranean ancestry.
  • Endemic KS: This type mostly affects people aged under 40 in central and eastern Africa.
  • Epidemic KS: This is the most common type in the United States. It develops in people who have HIV.
  • Iatrogenic, or transplant-related KS: This type of KS can develop when a person’s immune system has weakened after an organ transplant.

There is a wide range of treatments for KS. Treatment will depend on a person’s symptoms, the location/extent of disease involvement, and the presence of swelling.

A person’s general health and how well their immune system functions will also be factors in their treatment. Options include:

  • Cryotherapy: Also called cryosurgery, this involves freezing the skin lesions with liquid nitrogen to destroy the cancerous tissue.
  • Electrodesiccation and curettage: This involves removing lesions from the feet or removing the affected skin area. A doctor then uses an electrode to destroy any remaining cancer cells in the surrounding skin.
  • Chemotherapy: This can include topical agents or intravenous chemotherapy.
  • Radiotherapy: High-energy X-rays or other radiation can treat skin lesions confined to a limited area. This is most effective for treating classic KS in the early stages of the disease. In advanced cases of KS, a healthcare professional may also use radiotherapy to reduce pain and bleeding.

For people with AIDS-related types of KS (epidemic KS), a healthcare professional will prescribe high-activity antiretroviral therapy (HAART), sometimes on its own or in combination with other KS treatments.

HAART treats HIV infections using three or more drugs. The treatment reduces the risk of epidemic Kaposi sarcoma, although not completely. HAART may also stop advanced KS from developing in people with HIV, although not in all cases.

This list is not exhaustive, and other therapies and new approaches are currently undergoing clinical trials.

If a person has symptoms of KS, it’s important to obtain medical advice and begin treatment quickly. This is because early KS detection often leads to better outcomes.

Usually, KS develops slowly, and healthcare professionals can treat it successfully. However, it can be fatal if left untreated. People should not let others touch their lesions if they think they have KS.

Here are some frequently asked questions about Kaposi sarcoma.

What can be mistaken for Kaposi sarcoma?

The following conditions can appear like KS and appear in the same parts of a person’s body:

KS skin lesions can also look like other inflammatory skin conditions. Healthcare professionals diagnose KS by taking samples from the lesions (a tissue biopsy).

Is Kaposi sarcoma fatal?

KS is not always fatal, but the chance of successful treatment is affected by the following:

  • the type of KS
  • a person’s overall health
  • the health of their immune system
  • how early the condition is detected

These factors also affect treatment choice.

Kaposi sarcoma can cause skin lesions to appear on a person’s feet. These lesions may look like purple, reddish-blue, or brown skin marks. They can also appear as raised pimples, bumps, and discoloration.

Skin lesions can also appear on other body parts. People should speak with a healthcare professional to receive an accurate diagnosis.

Several effective treatments are available for KS. However, it can be fatal if not diagnosed and treated early.