Kaposi Sarcoma

What Kaposi sarcoma is

Kaposi sarcoma grows from the endothelial cells that line small blood and lymph vessels. The lesions are made of tangled abnormal vessels and spindle-shaped cells, which is why they look purple or bruise-like and do not blanch when pressed. Unlike most cancers, KS often arises in several places at once rather than spreading from a single tumor.

Infection with KSHV/HHV-8 is necessary but not sufficient. Most people infected never develop KS. Disease appears when immune control of the virus fails.

Types of Kaposi sarcoma

A fifth group, KS in men who have sex with men without HIV, is uncommon and usually mild.

Symptoms

Skin

• flat patches (macules) that are pink, red, purple or brown, depending on skin tone; on darker skin they may look dark brown or black
• patches that thicken into raised plaques or firm nodules
• usually painless and not itchy
• common on the legs, feet, face, nose, ears and genitals
• lesions that follow skin creases or appear in lines

Mouth

Purple patches on the hard palate, gums or tongue are common in HIV-related KS and can be the first sign.

Swelling

Lesions blocking lymph vessels cause firm swelling of the legs, feet, genitals or face (lymphedema), which can be painful and limit walking.

Internal organs

• Gut: often silent; can cause bleeding, pain or blockage.
• Lungs: cough, breathlessness, chest pain and coughing up blood. Lung KS is the most dangerous form.
• Lymph nodes: swollen nodes, especially in endemic KS.

Early stages

Early KS often looks like a bruise, a small birthmark, or a flat purple spot. Doctors may initially consider hemangioma, bacillary angiomatosis (a bacterial infection in HIV), pyogenic granuloma or melanoma.

Causes and risk factors

• KSHV/HHV-8 infection: spread mainly through saliva, and also sexually, through organ transplants and shared needles. It is common in parts of Africa and the Mediterranean.
• HIV: untreated HIV with a low CD4 count greatly raises the risk. KS is an AIDS-defining illness. Since effective HIV treatment became widespread, epidemic KS has become much less common in the US, but it can still occur with well-controlled HIV.
• Immunosuppressive drugs after an organ transplant or for autoimmune disease.
• Age and ancestry for classic KS.

How Kaposi sarcoma is diagnosed

• Skin or mucosal biopsy: the only way to confirm KS. Staining for the HHV-8 protein LANA-1 confirms it.
• HIV test and CD4 count: recommended for everyone newly diagnosed with KS.
• Physical exam: including mouth, genitals, lymph nodes and legs.
• Further tests depending on symptoms: stool test for blood, endoscopy or colonoscopy, chest X-ray or CT, and bronchoscopy for suspected lung disease.

KS is not staged like most solid tumors. For HIV-related KS, doctors use the ACTG system, which grades the tumor extent, CD4 count and overall illness as good or poor risk.

Kaposi sarcoma treatment

Treatment depends on the type, extent, symptoms and immune status. The goal is usually control, not cure.

Restore the immune system

• HIV treatment (antiretroviral therapy, ART): the foundation of treatment for epidemic KS. It alone controls limited disease in many people. Lesions occasionally flare in the first weeks, called immune reconstitution inflammatory syndrome (IRIS).
• Reducing immunosuppression in transplant patients, often switching to sirolimus, which has anti-KS activity.

Local treatments for limited skin lesions

• Radiation therapy: very effective for painful or visible lesions and swelling.
• Injections of chemotherapy (vinblastine) into lesions.
• Cryotherapy (freezing), laser, or minor surgery for small lesions.
• Topical alitretinoin gel for some skin lesions.
• Camouflage makeup for cosmetic concerns.

Systemic treatment

For widespread skin disease, lymphedema, or organ involvement:

• Liposomal doxorubicin is the usual first chemotherapy.
• Paclitaxel is used if first-line treatment fails.
• Pomalidomide is FDA-approved for KS after prior chemotherapy.
• Immunotherapy and other targeted drugs are being studied in clinical trials.

Classic KS

Slow-growing classic KS on the legs may simply be watched, or treated with radiation, local therapies or low-intensity chemotherapy when lesions become painful or cause swelling.

Outlook

The outlook depends on the type and immune status. Classic KS usually progresses slowly and rarely shortens life. HIV-related KS has a much better outlook since the arrival of effective ART, and many people achieve long-term remission. Lung involvement, very low CD4 counts and other HIV complications worsen the outlook. Transplant-related KS often regresses when immunosuppression is reduced. KS can recur, so long-term follow-up is needed.

Prevention

• HIV testing and early treatment prevent most epidemic KS.
• Safer sex and not sharing needles reduce HIV and HHV-8 transmission.
• Transplant teams monitor high-risk recipients and check skin regularly.

Frequently asked questions

What does Kaposi sarcoma look like at first?

Early Kaposi sarcoma usually appears as one or more flat, painless spots that are pink, red, purple or brown, often on the lower legs, face or roof of the mouth. They can look like bruises that do not fade. Over time they may become raised plaques or nodules.

Is Kaposi sarcoma always related to HIV?

No. It is most common with untreated HIV, but classic KS affects older men of Mediterranean or Eastern European descent, endemic KS occurs in Africa regardless of HIV, and iatrogenic KS develops in people taking immunosuppressive drugs, such as transplant recipients.

Is Kaposi sarcoma contagious?

The cancer itself does not spread from person to person. The virus that causes it, KSHV (HHV-8), can be passed on, mainly through saliva and sexual contact. Most people infected with the virus never develop Kaposi sarcoma unless their immune system is weakened.

Can Kaposi sarcoma be cured?

In HIV-related KS, effective HIV treatment, with or without chemotherapy, can make lesions disappear for many years. Transplant-related KS often regresses when immunosuppressive medicines are reduced. Classic KS is usually controlled rather than cured. Recurrence is possible, so ongoing checkups are important.

How fast does Kaposi sarcoma spread?

It varies. Classic KS on the legs can stay limited for many years. HIV-related KS can spread quickly over weeks to months in someone with a very low CD4 count. Endemic KS in children can be aggressive. Starting treatment promptly slows or reverses progression.