How Kaposi Sarcoma Is Diagnosed

Kaposi sarcoma (KS) is one type of a rare group of cancers called soft tissue sarcomas. KS develops from the endothelial cells that line the blood and lymph vessels.

Your doctor can sometimes tell if you have KS just by looking at lesions on your skin, but you will usually need to have a biopsy to confirm the diagnosis. If you are diagnosed with KS, you may need to have further tests such as imaging scans to check whether the cancer has spread to other parts of your body.

This article overviews how KS is diagnosed, including self-checks that you can perform at home and medical tests that might be ordered by your doctor.

What Does Kaposi Sarcoma Look Like?

Verywell / Jessica Olah


The first symptom of KS is usually a spot on the skin. KS skin lesions can be pink, brown, brown-red, or reddish-purple. The lesions look like a bruise, but unlike a bruise, they do not lose their color (blanch) when you press on them.

The lesions can appear as a:

  • Flat area on the skin (patch)
  • Slightly raised area (plaque)
  • Raised bump (nodule)

KS lesions can develop anywhere on the skin but commonly appear on the legs, face, and groin area. They can also occur inside the mouth.

It’s not possible to self-diagnose KS. If you notice lesions on your body, talk to your doctor.

Physical Examination

If your doctor thinks you might have KS, they will perform an examination of your skin and ask you questions about your health and medical history, including any illnesses or operations that you have had, your sexual activity, and any potential exposures to the virus that causes KS (Kaposi sarcoma-associated herpesvirus).

Your doctor will examine your skin and the inside of your mouth to look for KS lesions. They might want to do additional tests after completing an exam to confirm the diagnosis.

People with HIV are at an increased risk for KS. People with HIV need to be regularly checked by a healthcare provider who is knowledgeable about KS and other diseases that can occur alongside an HIV infection and AIDS. 

Labs and Tests

To make a definitive diagnosis of KS, your doctor will need to take a small sample of tissue from the lesion. This sample is called a biopsy.

A punch biopsy is usually done for skin lesions. During the procedure, your doctor will remove a very small, round piece of tissue from the lesion. To make sure that you do not feel any pain, you can be given a local anesthetic.

After the biopsy, the sample is sent to a pathologist—a doctor who specializes in examining tissue for evaluation.


If your doctor wants to look for signs of KS in other parts of your body, there are several tests that they can use:

  • X-ray: A chest X-ray can look for KS in the lungs.
  • Endoscopy: An endoscopy helps your doctor look for KS in the upper digestive tract, including the esophagus and stomach. A long, thin tube with a camera and a biopsy tool on the end is used to look around inside the body and take tissue samples.
  • Bronchoscopy: A bronchoscope is inserted through the nose or mouth into the windpipe (trachea) and lungs to look for KS in the lungs. A bronchoscope is a thin, tube-like instrument with a light and a lens for viewing. It sometimes has a tool attached that can be used to remove tissue samples, which are then checked under a microscope for signs of disease.
  • CT scan or MRI: These imaging scans can be carried out to see if the cancer has spread to other organs (metastasized).


Staging is a way of describing where the cancer is located, if or where it has spread, and whether it is affecting other parts of the body.

The staging of KS has not been unified or incorporated into the American Joint Committee on Cancer (AJCC) tumor, node, and metastasis (TNM) staging system.

The outlook is typically good for people with AIDS-related KS (the most common type in the United States). However, the prognosis is influenced as much by the presence of other AIDS-related conditions as it is by the spread of KS.

An individual’s prognosis relies on several factors such as how much their immune system is damaged and whether they have any AIDS-related infections.

Differential Diagnoses

There are many types of noncancerous (benign) blood vessel tumors. These tumors can have an appearance similar to KS lesions and need to be ruled out before a KS diagnosis is made.

Other conditions that can look similar to KS are:

  • Hematoma: A large clot of blood that accumulates outside of a blood vessel in tissue
  • Dermatofibroma: A harmless skin growth
  • Purpura: Spots that are caused by bleeding from the small blood vessels under the skin


Kaposi sarcoma (KS) is a rare but treatable type of cancer. It is especially common in people with HIV. KS is characterized by lesions, which often appear first on the skin. While a doctor might be able to tell if a person has KS just by examining their skin, other tests—like a biopsy or imaging scans—can also be done to confirm the diagnosis and determine whether the cancer has spread to other parts of the body.

A Word From Verywell

If you have HIV, your healthcare team will likely monitor you for Kaposi sarcoma because the cancer is more common in people with HIV. You can also get KS if you do not have HIV.

If you notice any unusual lesions on your skin, it’s important to tell your doctor. They can look at the lesions and do tests, like taking a tissue sample or doing imaging scans, to figure out if you have KS or another condition.

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5 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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