Kaposi’s Sarcoma

Kaposi’s sarcoma is a type of cancer that forms in the lining of blood and lymph vessels, causing distinctive colored skin lesions that can also affect internal organs in more severe cases.

Table of contents

• What is Kaposi’s Sarcoma?
• Types of Kaposi’s Sarcoma
• What Causes Kaposi’s Sarcoma
• Signs and Symptoms
• How Doctors Diagnose Kaposi’s Sarcoma
• Treatment Approaches
• Outlook and Follow-up

What is Kaposi’s Sarcoma?

Kaposi’s sarcoma is a type of cancer that develops from cells lining blood vessels and lymph vessels. The disease creates growths called lesions, which are abnormal areas of tissue that appear most commonly on the skin but can also develop inside the body^[1]. These lesions often appear as patches, spots, or bumps on the skin in colors ranging from pink and red to purple and brown^[1][2].

Unlike most cancers that start in one place and then spread to other parts of the body, Kaposi’s sarcoma can begin in several areas of the body at the same time^[6]. The lesions typically form on the face, arms, and legs, but can also appear on the genitals or inside the mouth^[1]. In more severe cases, lesions can develop in internal organs such as the digestive tract, lungs, liver, and lymph nodes^[1][2].

The disease was first described in 1872 by Moritz Kaposi, an Austro-Hungarian dermatologist who observed it in five patients^[3]. From that time until the HIV and AIDS epidemic in the 1980s, Kaposi’s sarcoma remained a rare tumor^[5].

Types of Kaposi’s Sarcoma

There are four main types of Kaposi’s sarcoma, each affecting different groups of people and progressing at different rates^[1][2].

Classic Kaposi’s sarcoma occurs primarily in older men, typically between ages 50 and 70, of Mediterranean, Eastern European, or Middle Eastern descent^[1][3]. This type usually grows slowly over 10 to 15 years or more and is often limited to one or both lower legs, especially the ankles and soles^[10]. Swelling in the legs and lymph buildup are common complications^[10]. As many as 33% of patients with classic Kaposi’s sarcoma develop a second primary cancer, most often non-Hodgkin lymphoma^[10].

Endemic Kaposi’s sarcoma, also called African Kaposi’s sarcoma, affects people living in Sub-Saharan Africa, particularly near the equator^[2][6]. This form is more aggressive than classic Kaposi’s sarcoma and affects both adults and children^[6]. While adults present with symptoms similar to classic Kaposi’s sarcoma, children can develop more aggressive disease with widespread lymph node involvement, significant swelling, and spread to internal organs^[14].

AIDS-related Kaposi’s sarcoma, also known as epidemic Kaposi’s sarcoma, is the most common type in the United States^[2]. This form occurs in people infected with HIV, particularly those not taking highly active antiretroviral therapy (HAART)^[3]. It can affect many parts of the body, including the skin and internal organs^[3]. Over 35% of people with AIDS may be affected by Kaposi’s sarcoma^[5].

Transplant-related Kaposi’s sarcoma, also called iatrogenic Kaposi’s sarcoma, happens in people who take medicines to suppress their immune system after an organ or bone marrow transplant^[1][2]. This type mostly affects the skin but can spread to other parts of the body^[3].

What Causes Kaposi’s Sarcoma

The main cause of Kaposi’s sarcoma is infection with human herpesvirus 8 (HHV-8), also known as Kaposi’s sarcoma-associated herpesvirus (KSHV)^[1][3]. This virus is present in all forms of Kaposi’s sarcoma^[3]. The virus infects the cells that line blood and lymph vessels, and it is thought that this causes them to become cancerous^[6].

HHV-8 is mostly transmitted through sexual contact and can also spread through blood between people who share needles^[6]. It is a common infection, but not everyone infected with HHV-8 develops Kaposi’s sarcoma^[6]. In healthy people, this infection usually causes no symptoms because the immune system keeps it under control^[1].

The virus interferes with many normal cell functions and requires additional factors like certain proteins or immune system problems to result in the development of Kaposi’s sarcoma^[3]. Scientists agree that having a weakened immune system or certain types of infection along with HHV-8 plays an important part in a person developing the disease^[6].

Several risk factors increase the likelihood of developing Kaposi’s sarcoma. Being male increases risk, as men are affected more often than women at a ratio of approximately 10 to 15 men to 1 woman in classic Kaposi’s sarcoma^[10]. Age also matters, as the disease mostly affects people between ages 40 and 70^[2]. People of Mediterranean, Southwest Asian, Eastern European, or Ashkenazi Jewish descent have a higher risk^[2].

The most significant risk factor is having a weakened immune system from HIV/AIDS or from taking immunosuppressive medicines after an organ transplant^[1][2]. Having unprotected sex increases the risk of contracting both HHV-8 and HIV, with men who have sex with men and bisexual men having higher risk^[2][15].

Signs and Symptoms

The symptoms of Kaposi’s sarcoma vary depending on whether the lesions are on the skin or inside the body^[6].

Skin Lesions

Lesions on the skin are more common than internal lesions^[6]. They usually start out very small and flat, appearing most often on the face, arms, or legs^[1][6]. These lesions may look like bruises but do not lose their color when pressed, unlike actual bruises^[6]. They can be red, purple, brown, pink, or blue in color^[1][2].

As the lesions grow, they might start to rise above the surrounding skin and grow into each other^[6]. The lesions typically do not cause pain or itching at first and seem harmless^[6]. However, they can eventually form nodules that may become ulcerated and bleed^[6]. Some lesions grow very slowly with no changes for months, while others grow more quickly with new areas appearing weekly^[6].

Internal Symptoms

When Kaposi’s sarcoma affects internal organs, symptoms depend on which organs are involved^[6]. Lesions in the lungs can cause shortness of breath or coughing up blood^[2][22]. Lesions in the digestive system can lead to belly pain, blood in stool, constipation, diarrhea, or vomiting^[2].

Lesions in the mouth can cause pain when eating^[2]. When Kaposi’s sarcoma affects lymph nodes, it can block the flow of fluid through the lymphatic system, causing painful swelling in the arms or legs called lymphedema^[6]. This swelling can be very uncomfortable, and early treatment is important to help control it^[6].

How Doctors Diagnose Kaposi’s Sarcoma

Because Kaposi’s sarcoma is rare, getting an accurate diagnosis can take time and may require seeing several different healthcare providers and specialists^[2].

Physical Examination

Diagnosis begins with a physical examination where the healthcare provider checks the skin for lesions and asks about symptoms and health history^[2][9]. They will look at the mouth and check for any unusual lumps or changes^[2].

Skin Biopsy

A skin biopsy is the main test to confirm Kaposi’s sarcoma^[9]. The healthcare provider removes a small piece of a skin lesion and sends it to a laboratory for testing^[9]. Lab tests look for signs of cancer and can detect the viral protein from HHV-8 in the tissue^[11].

Testing for Internal Disease

If doctors suspect Kaposi’s sarcoma inside the body, additional tests may be needed^[9]. Tests to find Kaposi’s sarcoma in the digestive tract include a fecal occult blood test to detect hidden blood in stool, an endoscopy to look at the esophagus and stomach, a colonoscopy to examine the colon, or a CT scan of the abdomen and pelvis^[9].

Tests to find Kaposi’s sarcoma in the lungs include a chest X-ray, a CT scan of the chest, or a bronchoscopy in which a thin tube is passed through the nose or mouth into the lungs^[8][9].

Treatment Approaches

There is no cure for Kaposi’s sarcoma because there is no treatment available to eliminate HHV-8 infection^[15]. Instead, the purpose of therapy is to relieve symptoms and slow disease progression^[15]. Treatment decisions vary depending on the type of Kaposi’s sarcoma, whether symptoms are present, and how widespread the disease is^[15].

Treatment for Classic Kaposi’s Sarcoma

Classic Kaposi’s sarcoma usually has a slow course, and observation alone may be sufficient for people without symptoms who have a healthy immune system^[15]. Lower leg swelling can be managed with compression stockings^[18]. Local therapies such as surgery, radiation therapy, cryotherapy, or chemotherapy injected directly into lesions can treat bothersome or cosmetically unacceptable lesions^[15]. Chemotherapy given throughout the body is reserved for patients in whom local therapy fails or who have extensive disease^[15].

Treatment for AIDS-Related Kaposi’s Sarcoma

Treatment for AIDS-related Kaposi’s sarcoma centers on the use of highly active antiretroviral therapy (HAART), which has decreased both the occurrence and severity of this disease^[15]. HAART prevents and often treats Kaposi’s sarcoma on its own^[5]. Most patients with less severe disease show tumor shrinkage with HAART alone^[15]. Local therapies can also be used for symptomatic or disfiguring skin lesions^[15]. Patients with more severe disease usually require a combination of chemotherapy with HAART^[15].

Treatment for Transplant-Related Kaposi’s Sarcoma

Transplant-related Kaposi’s sarcoma commonly responds to reducing or stopping immunosuppressive medicines^[15]. In one study, reducing immunosuppression alone led to complete or partial shrinkage of Kaposi’s sarcoma in 9 of 20 patients^[15]. However, this approach may not always be possible and can put patients at risk for organ rejection^[15]. Several studies have shown benefit from switching from certain immunosuppressive drugs to a medication called sirolimus, which may have a direct effect against Kaposi’s sarcoma tumor cells^[15].

Treatment Options

Various treatment options are available depending on the extent of disease. For localized skin lesions, options include surgical removal, injections of chemotherapy directly into the lesion, or radiation therapy^[4]. For widespread disease, treatment may include chemotherapy or biologic therapy^[4]. The least invasive and least toxic treatment should be used, especially in people with weakened immune systems who have higher risk for infections^[15].

Outlook and Follow-up

The outlook for people with Kaposi’s sarcoma varies greatly depending on the type and extent of disease and the person’s immune system function^[8]. With widespread disease, death may occur^[2]. However, many people can live with controlled disease for extended periods with proper treatment.

Follow-up care is an important part of treatment and safety^[18]. People should make and attend all appointments and contact their doctor if they are having problems^[18]. It is important to let the doctor know about any new Kaposi’s sarcoma spots, swelling that might be lymphedema, or if improvement does not occur as expected^[18].

Kaposi’s sarcoma can return even after successful treatment^[2]. Regular monitoring helps detect any recurrence early so treatment can begin promptly.