Kaposi's sarcoma - What is Kaposi's sarcoma?
The trillions of the cells in the body grow normally, divide, and then die accordingly. Once adulthood is reached cells divide only to replace worn-out or dying cells or to repair injuries.
What happens to cells in cancer?
Cancer starts when cells in a certain organ or part of the start to grow out of control. Cells become cancer cells because of damage to DNA.
Different types of cancer can behave very differently – some may remain at one location while others spread rapidly to other major organs via blood stream or via lymphatic channels. (1-4)
How does Kaposi's sarcoma develop?
Kaposi's sarcoma is a cancer that develops from the cell lining the lymph or blood vessels. The cancer appears as red, purple, or brown raised tumors or spots over the skin.
These lesions are usually non-symptomatic but may cause painful swelling in some areas like legs, groin or skin around the eyes.
Kaposi's sarcoma may become life threatening when it affects major organ like lungs, liver, or the gastrointestinal tract. In the gastrointestinal tract it may lead to bleeding while in the lungs it may lead to severe difficulty in breathing.
Who discovered Kaposi's sarcoma?
Kaposi's sarcoma was first described by Moritz Kaposi, a Hungarian dermatologist in 1872. (2)
Who is at risk of Kaposi's sarcoma?
An HIV-infected person has a 20,000 times increased risk of developing Kaposi's sarcoma to a person without HIV. In the early 1990’s there were approximately 47 cases per million people per year among the HIV infected individuals of United States.
With the advent of anti-HIV drugs the numbers have fallen and it now occurs at a rate of about 7 cases per million people each year.
The rates are highest in Africa where Kaposi's sarcoma herpesvirus (KSHV) (also known as human herpesvirus type 8 - HHV-8) and HIV infection rates are high. About 1 in 200 transplant patients in the United States gets Kaposi's sarcoma. (1-4)
Type of Kaposi's sarcoma
The major types of Kaposi's sarcoma are (1-4):
- AIDS-related or Epidemic Kaposi's sarcoma – This is the commonest type of KS in the United States. It affects patients infected with HIV. An HIV positive patient may harbor the virus in his or her body for years before getting AIDS. AIDS begins when the virus has severely debilitated the immune system. This damage to immune system leads to infections and complications like Kaposi's sarcoma. The CD4 count in blood is a measure of the effect of HIV on the immunity. The lower the CD4 count, the more likely that the patient will get Kaposi's sarcoma. Kaposi's sarcoma indicates that an HIV positive individual officially has AIDS and thus is called an “AIDS defining” illness.
- Classic Kaposi's sarcoma or Mediterranean Kaposi's sarcoma – This affects the elderly living in Mediterranean, Eastern European, and Middle Eastern regions for generations and the Ashkenazi Jews. It affects men more than women. Ashkenazi Jews are people who are descended from Jewish communities that lived in Central and Eastern Europe. Most Jewish people in England are Ashkenazi Jews. Lesions typically begin as one in the legs, ankles, or the soles of the feet. The lesions are usually slow to grow. The immune system of people with classic Kaposi's sarcoma is not as weak as it is in those who have epidemic Kaposi's sarcoma.
- Endemic Kaposi's sarcoma or African Kaposi's sarcoma – this affects people living in Equatorial Africa. These people are more at risk of developing infection with Kaposi's sarcoma Herpes Virus (KSHV). This form of Kaposi's sarcoma affects younger people under age 40. Rarely an aggressive form of the illness may be seen in children before puberty.
- Organ transplant-associated Kaposi's sarcoma – In individuals whose immune systems have been suppressed after an organ transplantation to prevent the body from rejecting the new organ, there is a risk of Kaposi's sarcoma. Most transplant patients need to immunosuppressant drugs to keep the immune system from attacking and killing the new organ that is perceived as a foreign object. If drugs weaken the immunity there is a risk of infection with KSHV and development of Kaposi's sarcoma.
- Kaposi's sarcoma in HIV negative men who have sex with men – this group is found to get mild cases of Kaposi's sarcoma similar to classic Kaposi's sarcoma.
Treatment of Kaposi's sarcoma
Kaposi's sarcoma can be treated using a combination of anti-HIV medication chemotherapy, radiotherapy and surgery.
Prognosis or outlook of Kaposi's sarcoma alone is good. Provided people with HIV-related Kaposi's sarcoma get access to anti HIV medication early on in their HIV disease, they can go into remission with regression of symptoms.
Causes of Kaposi's sarcoma
Kaposi's sarcoma is a form of cancer that affects people with decreased immunity. It is seen in patients with HIV infection, elderly men of Mediterranean, Jewish or African descent and patients taking drugs for suppression of immunity after organ transplantation.
Kaposi's sarcoma and AIDS
The rise of number of cases of Kaposi's sarcoma occurred in the 1980s and 1990s as the number of AIDS cases soared.
After the advent of anti HIV drugs called the highly active antiretroviral therapy (HAART) the incidence of Kaposi's sarcoma has reduced. However Kaposi's sarcoma remains a commonly reported cancer in some African countries commonly due to untreated HIV infection.
Causes of Kaposi's sarcoma
Causes of Kaposi's sarcoma include (1-4):
- Endemic or African Kaposi's sarcoma affects young adult men in equatorial Africa with a normal immune system. Up to 9% of Ugandan men suffer from this condition. Sometimes children may be affected as well.
In them the cancer invades the lymph nodes and lymphatic channels and spares the skin. This is usually associated with spread to other organs may be fatal.
- Transplant-related or acquired Kaposi's sarcoma. Patients after an organ transplant need immunity suppressing drugs. This prevents the patient’s immunity from attacking and killing the newly transplanted organ. These patients on immunity suppressing drugs are at risk of Kaposi's sarcoma.
- Epidemic or HIV associated Kaposi's sarcoma. This is the commonest cause of Kaposi's sarcoma.
- Kaposi's sarcoma-associated herpes virus (KSHV) or Human herpes virus 8 (HH8) is a common infection that can lead to Kaposi's sarcoma. KSHV belongs to the herpes virus family.
This virus is similar to Epstein-Barr virus. The EB virus causes infectious mononucleosis or glandular fever and contributes to several types of cancer like lymphomas.
The KSHV brings in genetic material into the cells. These altered genes cause the cells to divide too much and unnecessarily leading to cancer. HHV-8 does not cause Kaposi's sarcoma in everyone who develops the virus. The virus only seems to cause Kaposi’s sarcoma in people with a high risk.
Risk factors of getting Kaposi's sarcoma
Risk factors of getting Kaposi's sarcoma include (1-4):
- Men are more commonly affected. In African countries male patients who are not HIV positive are more frequently affected with the virus than females.
- Men of the Mediterranean, Middle Eastern or African origin and of Ashkenazi Jewish descent are more at risk. This could be due to an inherited vulnerability to HH8 virus.
- Men who have sex with men are more at risk. Homosexual as well as heterosexual partners of Kaposi's sarcoma patients are at risk of HH8 infection.
- Those with a suppressed immunity with HIV AIDS infection are at a greater risk of Kaposi's sarcoma.
- Those with diabetes and on oral corticosteroid medications are at risk. These conditions lead to decrease in immunity and thus may lead to the predisposition.
Symptoms of Kaposi's sarcoma
Kaposi's sarcoma is a cancer that affects the linings of the blood vessels of lymphatic channels in persons with a lowered immunity typically patients with HIV infection.
Types of Kaposi's sarcoma
Classic Kaposi's sarcoma is rare and affects elderly men of Mediterranean or Ashkenazi Jewish origin.
Endemic or African Kaposi's sarcoma affects young adults living in equatorial Africa. These patients usually have a normal immune system.
Course of the disease
In most cases the course of the disease is slow but in some patients it may assume an aggressive and faster progress.
Children can also be affected with the endemic variety. This form in children usually affects the lymphatic channels and may spread to other organs and become life threatening.
Symptoms of Kaposi's sarcoma
Symptoms of Kaposi's sarcoma include (1-4):
- Node like raised or blotchy flat patches over the skin. These are red, purple, brown or black. These are usually the first symptoms of Kaposi's sarcoma. The lesions can develop quickly and enlarge in size.
Although there may be a single area at first, it is possible for more than one to appear. Often the lesions merge to form a larger tumor. They are most commonly seen over the face around the mouth, ears and tip of the nose. Lesions are also seen commonly over the legs and feet, and genital area.
In dark skinned individuals the lesions are noted as dark brown or black.
- Lesions similar to those on the skin are sometimes visible under or on mucous membranes especially in the mouth, nose, gums, tongue, over the tonsils, over the palate (roof of the mouth) or throat.
- The skin lesions are more often than not painless and non-itchy. They may become painful if there is inflammation or swelling.
- There may be a superimposed or secondary bacterial infection over the skin lesions. Since the patient usually has lowered immunity there is also a risk of secondary infections in other organs like lungs (e.g. pneumonia) etc.
- Some aggressive tumors may spread to other organs. If the spread is in lungs there are respiratory problems and associated symptoms. In case of liver metastasis there are signs of liver damage like jaundice etc.
- Lesions occurring in the oesophagus (food pipe) or respiratory tract may grow to obstruct feeding or breathing respectively.
- Lung affection may lead to breathing difficulties, blood in the sputum and respiratory failure, gastrointestinal tract affection may lead to bleeding (that may be fatal) and affliction of the lymphatic channels may lead to swollen lymph nodes and lymphatic channels.
Swollen and blocked lymphatic channels lead to swollen limbs and is called lymphedema. Lesions in the gastrointestinal tract may lead to nausea, diarrhea, bleeding with stools and vomiting in some individuals.
- Over a long term bleeding may lead to anemia. This is caused due to lowering in the number of red blood cells.
Diagnosis of Kaposi's sarcoma
Kaposi's sarcoma diagnosis in most cases is made clinically and suspected in high risk individuals. High risk individuals include those with HIV infection and those who have received an organ transplant and are receiving immunity suppressing drugs.
Process of diagnosis of Kaposi's sarcoma
Diagnosis of Kaposi's sarcoma includes the following steps (1-4):
- Detailed clinical and medical history including sexual orientation and history of exposure and unprotected sex.
This includes taking a history of or current HIV infection. Elderly males of Mediterranean and Ashkenazi Jewish descent and those living in equatorial Africa are especially evaluated for Kaposi's sarcoma.
- Physical examination. A detailed physical examination is conducted. An oral exam is conducted to see lesions in the mouth.
Rectum and the groin are inspected for lesions as well. Lymph nodes and lymphatic system is also examined in detail.
- Routine blood tests are prescribed to detect abnormalities like anemia and low White blood cell count denoting lowered immunity.
- Blood test for HIV. This is done because HIV infection is the commonest cause for Kaposi's sarcoma.
CD4 cell counts are assessed. If the CD4 cell counts are low there is a higher risk of Kaposi's sarcoma.
- Skin lesions may be mistaken for fungal infections or another type of cancer, non-Hodgkin's lymphoma. These conditions should be ruled out before diagnosis of Kaposi's sarcoma is confirmed.
- Skin lesion biopsy. This is a quick procedure and can be done in an outpatient department.
The skin over the lesion is cleaned with an antiseptic. A small piece of the lesion is cut and removed with a scalpel blade. The area is then dressed and the wound covered. The sample is examined under the microscope.
The area may be sore for a few days. A punch biopsy involves taking a small piece of tissue, while an excisional biopsy involves removing the whole lesion.
Under microscope characteristic features include spindle cells (elongated tumour cells), dense and irregular blood vessels which leak blood into the tumour leading to the red color of the lesion and surrounding inflammation.
- A bronchoscopy is prescribed if lesions in the lungs are suspected. A thin fiber optic tube is inserted. It has a camera on its tube that facilitates viewing of the inner walls of the airways.
If bronchoscopy shows lesions in the lungs, samples may be taken for microscopic examination.
- An upper endoscopic examination is prescribed if lesions in the gastrointestinal tract are suspected. A thin fiber optic tube is inserted. It has a camera on its tube that facilitates viewing of the inner walls of the gastrointestinal tract.
The lower intestine may be examined using a sigmoidoscope that is inserted via the anus.
- A CT (computerised tomography) scan is prescribed to see if there is evidence of lesions in other parts of the body. A CT scan is painless and uses small amounts of radiation.
Staging of the cancer
Staging of the cancer is done based on three parameters. It is called the AIDS clinical trials group (ACTG) system. The parameters are (3-4) –
T - extent of tumour.
I - status of immune system according to the CD4 count.
S - extent of involvement of organs or systemic illness.
Each parameter has two subgroups zero (0, or good risk) or a 1 (poor risk).
For example T0 means a localized tumor and Kaposi's sarcoma is located only in the skin and the lesions in the mouth are flat rather than raised.
T1 indicates more wide spread lesions.
Edited by April Cashin-Garbutt, BA Hons (Cantab)