What is Kaposi Sarcoma?
Kaposi sarcoma is a kind of tumor that affects the soft tissues in the body. This type of tumor can appear in different groups of people and may show different symptoms and progress in various ways. Most commonly, Kaposi sarcoma is found in people whose immune systems are weak, such as those with Acquired Immune Deficiency Syndrome (AIDS) and people who have had an organ transplant and are taking medication to suppress their immune system.
The disease was first described in 1872 by Moritz Kaposi, a doctor from Austro-Hungary, in five patients who had the disease in many areas of their bodies. In the 1980s, researchers discovered that the Kaposi sarcoma herpesvirus (human herpesvirus/Kaposi sarcoma herpesvirus or HHV-8) causes Kaposi sarcoma. This discovery was made during the AIDS epidemic.
The disease can show up in four different ways:
- The first, called the classic form, usually affects older men from Mediterranean and Eastern European backgrounds. It typically shows up on their lower legs.
- The second is the endemic African form. This affects children and often involves the lymph nodes, which are small glands that make and store cells that fight infection.
- The third form is linked to HIV (the virus that can lead to AIDS). This type affects patients not taking specific HIV medicines (known as highly active antiretroviral therapy or HAART) and can involve the skin and internal organs.
- The last form is the iatrogenic form, which affects people who have weakened immune systems due to medication. This form also involves the skin and internal organs.
The course of the disease can vary for each form, with some developing slowly over time, and others being more aggressive and potentially leading to death, particularly the ones that are anaplastic (meaning the cells are abnormal and divide uncontrollably).
What Causes Kaposi Sarcoma?
The Human herpesvirus-8 (HHV-8) is found in all cases of a type of cancer known as Kaposi sarcoma. This virus disrupts many normal cell functions and needs additional elements like cytokines (proteins that influence the behavior of immune cells) to result in the development of Kaposi sarcoma.
HHV-8 is also associated with other types of cancer. These include plasmablastic multicentric Castleman disease (a rare disorder involving an overgrowth of cells in the body’s lymph nodes), primary effusion lymphoma (a rare form of non-Hodgkin lymphoma), intravascular large B cell lymphoma (a rare type of lymphoma that is mostly found in the blood vessels), and occasionally angiosarcoma (a cancer that forms in the lining of blood vessels and lymph vessels) and inflammatory myofibroblastic tumor (a rare tumor that often occurs in the lungs).
Risk Factors and Frequency for Kaposi Sarcoma
Classic Kaposi sarcoma is most often seen in men and people over 50 from Eastern Europe and the Mediterranean. This type of sarcoma is more common among these patients and puts them at a higher risk for other types of cancer. In the US, the frequency of this disease has remained stable. On the other hand, Endemic Kaposi sarcoma is unusually common among children and is related to the presence of the HHV-8 virus. This disease is widespread in Africa, with the number of cases among men and women decreasing from a 7:1 ratio to 2:1 since the start of the HIV epidemic in Africa. Now, it is the most common cancer among men and the second-most common among women in Uganda and Zimbabwe.
Worldwide, the presence of the HHV-8 virus varies significantly, with the highest rates seen in Saharan Africa, and the lowest rates in Northern Europe, Southeast Asia, and the Caribbean. The virus is also somewhat common in the Mediterranean, US, and South America. Among people with HIV, Kaposi sarcoma related to AIDS is the second-most common tumor, especially if they have a very low count of a certain type of immune cell (CD4). People with HIV who don’t take high-activity antiretroviral therapy may develop Kaposi sarcoma, and gay men with HIV are more likely to have this disease.
Iatrogenic Kaposi sarcoma, another type of this disease, more commonly affects men. Around 5% of transplant patients who develop a new case of cancer will develop Kaposi sarcoma, which is a lot higher than the general population. The risk is lower for those with bone marrow or blood stem cell transplants compared to solid organ transplant patients.
Signs and Symptoms of Kaposi Sarcoma
A routine health check and physical examination are conducted initially. During this exam, the doctor checks the skin for purple patches or swelled lymph nodes that could indicate a condition known as Kaposi sarcoma. If there are any suspicious marks on the skin or lymph nodes, a sample may be taken for lab testing. It’s especially important to examine the areas where the skin and mucous membranes meet as Kaposi sarcoma often shows up there first.
Testing for Kaposi Sarcoma
To conclusively identify Kaposi sarcoma, which is a kind of cancer, your doctor may need to take a small sample from the suspected area through a procedure called a biopsy, or they may need to remove the suspicious area entirely through an excision. This sample will then be studied in detail under a microscope by a professional called a pathologist. The pathologist will look out for specific features to confirm Kaposi sarcoma, such as unusual cell growth in the skin layer.
The pathologist uses a method called immunohistochemistry, which is a specialized lab test that uses antibodies to interact with the tissue sample in a way that makes it easier for them to observe specific cells, structures or microorganisms under the microscope. For Kaposi sarcoma, immunohistochemistry helps to identify the presence of LANA1, a marker indicating the presence of a virus known as HHV-8. This virus is often linked to Kaposi sarcoma.
Apart from LANA1, the suspicious cells are also expected to show CD34, factor VIII, PECAM-1, D2-40, VEGFR-3, and BCL-2. Together, the presence of these specific markers helps the pathologists to differentiate Kaposi sarcoma from other similar-looking conditions.
Treatment Options for Kaposi Sarcoma
Kaposi sarcoma is a type of skin cancer that can be treated in various ways, depending on its extent and progression. When it affects the skin, it can be treated by removing the affected part, using freeze therapy with liquid nitrogen, or injecting a chemotherapy drug called vincristine. This type of approach is specifically valuable in treating localized cancer that hasn’t spread to other body parts.
Chemotherapy, a treatment that uses drugs to destroy cancer cells, is often used for more widespread or aggressive forms of Kaposi sarcoma, especially in children.
In cases where Kaposi sarcoma is related to HIV, it’s found that the cancer responds well to a treatment known as HAART (Highly Active Antiretroviral Therapy), which helps control HIV. HAART can lead to the reduction or even complete elimination of the sarcoma. In severe instances, this anti-HIV treatment is combined with chemotherapy to combat the cancer.
Treating Kaposi sarcoma that occurs due to drugs suppressing the immune system (known as iatrogenic Kaposi sarcoma) can be challenging. It’s crucial to strike a balance between reducing these medications (or stopping them entirely) and preventing rejection of a transplanted organ, all while effectively treating the cancer.
What else can Kaposi Sarcoma be?
When examining skin lesions that have a spindle cell vascular nature, pathologists consider various possible diagnoses, including:
- Interstitial granuloma annulare
- Spindle cell hemangioma
- Acquired tufted angioma
- Kaposiform hemangioendothelioma
- Cutaneous angiosarcoma
- Fibrosarcomatous dermatofibrosarcoma protuberans
- Aneurysmal dermatofibroma
- Acroangiodermatitis
- Spindle cell melanoma
- High-grade sarcomas
Similarly, when diagnosing Kaposi sarcoma on areas of the body where mucous and skin meet, the following conditions may also be considered:
- Nevi
- Pyogenic granuloma
- Bacillary angiomatosis
- Hemangioma
- Angiosarcoma
- Melanoma
What to expect with Kaposi Sarcoma
About 10% to 20% of patients suffering from the typical form of Kaposi sarcoma, a type of skin cancer, may unfortunately pass away due to the disease. However, there’s a larger percentage of patients who could develop another form of deadly cancer. There are different types of Kaposi sarcoma, including endemic, HIV-related, and iatrogenic, each having different survival rate.
The patient’s likely outcome (or prognosis) often hinges on several factors. For those with HIV-related Kaposi sarcoma, the key factors include the number of a certain type of immune cell (CD4 count) and whether or not they have any additional opportunistic infections. Opportunistic infections are infections that occur more frequently in individuals with weakened immune systems.
For those suffering from iatrogenic Kaposi sarcoma (caused by certain medical treatments), the prognosis depends on their underlying health condition and their body’s capacity to endure a decrease in immunosuppression, or the reduction of the body’s ability to fight infections.
A worse prognosis is typically observed in patients where the disease has spread to vital organs like the lungs.
Possible Complications When Diagnosed with Kaposi Sarcoma
Larger sores may cause pain and swelling, resulting in changes in the skin’s appearance. If Kaposi sarcoma, a type of cancer, affects the lungs, it can make it hard to breathe and can even be fatal. There’s also a known risk of developing another type of cancer from classic Kaposi sarcoma.
Chemotherapy is a cancer treatment that can have damaging side effects. These side effects can include harm to the nervous system, fertility problems, heart damage, and pain in your nerves.
Radiation therapy, another cancer treatment, can lead to skin dryness, poor blood supply, slow healing, increased risk of new cancers, and swelling caused by blockage in your body’s system of waste removal.
Possible Side Effects:
- Pain
- Swelling
- Skin disfigurement
- Respiratory distress from lung involvement
- Potential death
- Increased risk of secondary cancers
- Chemotherapy effects: neurotoxicity, infertility, cardiac toxicity, nerve pain
- Side effects of radiation therapy: Skin dryness, reduced blood flow, poor healing, risk of new cancers, lymphedema
Recovery from Kaposi Sarcoma
After their treatment, patients should be regularly checked to ensure their disease has been completely resolved or to observe if it has come back.