Kaposi’s sarcoma can affect the cells lining mucous membranes, such as inside the mouth and tongue. It leads to lesions, or growths, on the skin of the tongue.

Research suggests that human herpesvirus 8 (HHV-8) causes Kaposi’s sarcoma. This condition is more common among immunocompromised people, especially those living with HIV. Kaposi’s sarcoma is an AIDS-defining illness, indicating that a person’s HIV has progressed to the advanced stage known as AIDS. The condition can also affect other groups, and researchers have identified four distinct types of Kaposi’s sarcoma.

People who notice atypical growths on their tongue or any other part of their mouth should seek medical care.

Read on to learn more about Kaposi’s sarcoma of the tongue.

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Kaposi’s sarcoma is a vascular tumor, which means the cancer develops in the blood vessels. It commonly affects cells that line blood vessels, lymph vessels, and mucous-covered surfaces on the body. This includes the mouth and tongue.

The disease does not initially cause symptoms, so a person is unlikely to notice pain in their tongue. Instead, they may typically notice one or a few growths on the tongue.

Classic Kaposi’s sarcoma commonly affects the extremities, which include the arms and legs. However, when cancer occurs in a person with HIV or AIDS, tumors in the mouth are typically more common.

What do lesions in the tongue look like

Lesions from Kaposi’s sarcoma on the tongue may appear as the following:

  • painless growths on the tongue
  • bloody-looking growths on the tongue
  • red, purple, or brown blisters or growths on the tongue that do not go away
  • new blood vessels inside growths on the tongue

The HHV-8 causes all forms of Kaposi’s sarcoma. It is more prevalent in certain areas of the world, especially sub-Saharan Africa, so rates of Kaposi’s sarcoma are also higher in these regions.

Though HHV-8 causes all instances of the disease, researchers have identified four distinct types:

  • Classic form: Classic Kaposi’s sarcoma is common among older Mediterranean and Eastern European men. Symptoms typically appear on the lower extremities.
  • HIV-related form: People living with HIV or AIDS — especially those not taking antiretroviral therapy — have a higher risk of Kaposi’s sarcoma affecting the skin and mouth. According to a 2021 paper, oral Kaposi’s sarcoma develops in as many as 65% of those with HIV, typically indicating an unfavorable outlook.
  • Endemic African form: This type commonly affects children and often appears in the lymph nodes. HHV-8 is more common in parts of Africa, leading to higher rates of Kaposi’s sarcoma.
  • Iatrogenic form: This type occurs in people with weakened immune systems that might result from immune-suppressing drugs, chemotherapy, or other medications. Like HIV and AIDS-related types, it can affect many different parts of the skin, including the mouth.

A doctor may suspect Kaposi’s sarcoma according to a person’s risk factors and the appearance of the lesions on their tongue.

To conclusively diagnose the condition, a doctor must biopsy the area or surgically remove the lesions and then send them to a lab for analysis. Kaposi’s sarcoma shows a number of specific markers and will also test positive for LANA1, a marker for HHV-8.

In some people, Kaposi’s sarcoma is the first symptom of HIV. Therefore, a doctor may order further blood tests to confirm a diagnosis.

What other conditions affect the tongue and look like oral Kaposi’s sarcoma?

A number of other conditions can resemble Kaposi’s sarcoma. Some include:

  • Hairy tongue: This condition causes the tongue to look hairy and dark, often after using antibiotics.
  • Canker sores: These are painful local infections in the mouth, cheeks, or tongue. They may be yellow, purple, flesh-colored, or red.
  • Oral hairy leukoplakia: These hairy growths in the mouth are more common in people with HIV and AIDS. They may signal the worsening or progression of either condition.
  • Squamous cell carcinoma: This type of skin cancer can affect the mouth and is more common in people over 40 years of age who smoke or use other tobacco products.
  • Nutritional issues: Sometimes, nutritional issues cause mouth sores. People who are dieting, have eating disorders, or do not have access to various food types, may be more vulnerable.
  • Pyogenic granulomas: These are benign lumps — often appearing red — that can occur in the skin or oral cavity.
  • Hemangiomas: These are benign growths of blood vessels that can occur anywhere in the body.
  • Gingival hyperplasia: This condition refers to the growth of excessive gum tissue. It can appear in transplant patients using cyclosporine medication, and doctors can confuse it for Kaposi’s sarcoma.

In people with HIV and AIDS, antiretroviral therapy can help treat the cancer and prevent it from returning. It will also slow or halt the progression of the disease.

Treatment requires surgically removing the lesions, and a person may need chemotherapy if the cancer has spread.

In most cases, Kaposi’s sarcoma responds well to treatment. However, it also often leads to secondary cancers that can be fatal.

The outlook is typically worse in people with health issues and those where the cancer has spread to the lungs. The overall 5-year survival rate is 75%.

Kaposi’s sarcoma of the tongue is uncommon in most Western nations but is more prevalent among people with HIV, AIDS, or other conditions affecting the immune system.

People who notice lesions on the tongue, especially if they have immune system issues, should promptly seek medical care. The condition responds well to treatment, but it can also be a sign of difficulties with managing HIV or AIDS that requires additional treatment.