What Is Kaposi Sarcoma

Overview

Kaposi sarcoma (KS) is a type of soft-tissue cancer that forms in blood and lymph vessels, causing purplish spots and lesions on the skin and mucosal areas, primarily the legs, face, genital area, mouth, and lymph nodes. Infection with human herpesvirus 8 (HHV-8) is the causative agent of developing Kaposi sarcoma. Not everybody infected with HHV-8 develops Kaposi sarcoma, though people with weakened immune systems, such as those with acquired immunodeficiency syndrome (AIDS), or organ transplant recipients on immune-suppressing drugs, are at higher risk of this cancer. Cancer resulting from AIDS infection is the most common type of Kaposi sarcoma, termed ‘Epidemic Kaposi sarcoma’.¹ 

Types of kaposi sarcoma

There are four different types of Kaposi sarcoma:²

• Epidemic Kaposi sarcoma- also known as ‘AIDS-related’ or ‘HIV-related’, is the most common type of KS, wherein individuals with a dysregulated immune system are at higher risk of suffering malignant effects of prior HHV-8 infection.
• Iatrogenic Kaposi sarcoma- also termed ‘Immunosuppressant-associated’ or ‘transplant-associated’, this type of KS is prevalent in those taking immunosuppressant drugs following organ transplant, putting them at more risk of HHV-8 infection. 
• Classic Kaposi sarcoma- is the rarest and slowest-developing form of KS cancer. It is associated with elderly males in ethnic backgrounds in countries where HHV-8 is more prevalent, such as Eastern European and Mediterranean countries. 
• Endemic Kaposi sarcoma- appears in some communities in Sub-Saharan Africa where HHV-8 is prevalent. 

Causes of kaposi sarcoma

• HIV and HHV-8 (KSHV) coinfection and;
• Suppression of the immune system due to medical treatment

Kaposi sarcoma arises most commonly in individuals with suppressed, non-functional, or dysregulated immune systems who are infected with Human Herpesvirus 8. Those with a functional immune system would usually combat this virus before cancer develops. 

Signs and symptoms of kaposi sarcoma

AIDS-related Kaposi sarcoma (KS) exhibits diverse clinical manifestations:

• Cutaneous lesions, usually of colours pink, purple, brown, and red, are prevalent in nearly all patients.
• Lesions manifest as multicentric, with a spectrum of developmental stages.
• Tumour-induced lymphedema is likely, particularly in the lower extremities or facial regions.
• Lesions on the soles of the feet can induce pain during walking.
• Gastrointestinal lesions are possible and manifest anywhere within the gastrointestinal tract; these may, but not always, cause stomach pain, vomiting, and bowel problems. 

Pulmonary system involvement may result in the following:

• Symptoms like cough, chest pain, and breathing difficulties.
• Exudative and bloody pleural effusions.

Oral involvement can display a range of manifestations:

• Isolated spots to bleeding, painful, necrotic swellings, and nodules.
• Lymphadenopathy – swelling of lymph nodes.
• Dysphagia (difficulty swallowing). 

Classic Kaposi sarcoma often follows a slower progression:

• Gradual enlargement of existing lesions and potential development of new ones.
• Cutaneous lesions predominantly in the lower extremities, the head and neck area.
• Lesions can vary in size, appearance, and colour.

Mucous membrane involvement is common and may impact daily functions:

• Potentially affecting speech or mastication.²

Diagnosis

Various tests are used to diagnose internal Kaposi's sarcoma:

• Faecal occult blood test- to identify concealed blood in stool.
• Chest X-ray- to identify any abnormalities in the lungs.
• Bronchoscopy-  to examine the lungs and collect samples only in the event of breathing difficulties or if abnormalities are detected on a chest X-ray.
• Upper endoscopy-  to examine the oesophagus, stomach, and small intestine. This is unnecessary if no blood is detected in the stool.¹
• Colonoscopy-  to examine the rectum and colon, but it is unnecessary if no blood is detected in the stool.¹
• Biopsy- of the lymph nodes or other tissue to analyse for tumour markers. 

Differential diagnosis

Bacillary angiomatosis and Kaposi sarcoma can be hard to distinguish. Bacillary angiomatosis is caused by Rochalimaea species and is treated with antibiotics.

Bacillary angiomatosis is characterised by capillary proliferation and neutrophilic inflammation. Meanwhile, slit-like vascular spaces and lymphoplasmacytic infiltrates are seen in Kaposi sarcoma.

Other possible differential diagnoses: Hematoma, Hemangioma, Dermatofibroma, Pyogenic granuloma, and Purpura.²

Management and treatment for Kaposi sarcoma

• No cure is currently available for Kaposi sarcoma (KS), but current treatment aims to alleviate symptoms and slow disease progression.
• Observation alone may be sufficient for immunocompetent asymptomatic patients with classic KS.
• Local therapies (surgical resection, radiotherapy, cryotherapy, intralesional chemotherapy) for symptomatic or cosmetically unacceptable lesions.
• Systemic chemotherapy is reserved for patients with local therapy failure or extensive disease.
• Highly active antiretroviral therapy (HAART) is used for epidemic KS in AIDS patients, though alone may result in tumour regression for low-risk patients.
• A combination of chemotherapy and HAART is recommended for poor-risk patients.
• Reduction or discontinuation of immunosuppression for iatrogenic or post-transplantation KS
• Cytotoxic (cell-killing) agents, such as Liposomal doxorubicin, paclitaxel, Bevacizumab, Pomalidomide, and Imatinib, are used for systemic therapy. Clinical trials for treatments like liposomal doxorubicin are being conducted in clinical oncology and HIV medicine.
• Local therapy (radiation) for palliation of advanced symptomatic disease or cosmetically unacceptable lesions.

Ultimately, treatment decisions are individual and depend on disease extent, symptoms, and therapeutic goals.

FAQs

How can I prevent Kaposi sarcoma?

• Currently, there is no vaccine or primary prevention for KSHV (Kaposi sarcoma-associated herpesvirus). Thus far, clinical trials to find inhibitors of KSHV have been unsuccessful. The most effective way to prevent the development of Kaposi sarcoma is to undertake HIV prevention measures, such as using protection during sex and avoiding blood contamination. Halting saliva exchange can also help prevent KSHV transmission at the population level.⁵

How common is kaposi sarcoma?

In the US, there are approximately 2,000 cases of Kaposi sarcoma per year. Kaposi sarcoma increased among men who have sex with men (MSM) during the AIDS epidemic, and having HIV remains a high risk factor for developing Kaposi sarcoma, though the incidence of Kaposi sarcoma has decreased since the introduction of HAART antiretroviral therapy. Kaposi sarcoma also occurs in heterosexual individuals. Kaposi sarcoma is more prevalent in central Africa, Mediterranean countries, and the Middle East, with classic Kaposi sarcoma primarily affecting men aged 50-70 years and endemic Kaposi sarcoma occurring at ages 35-40 years.²

Who is at risk of kaposi sarcoma?

The National Cancer Institute and the American Cancer Society identified these risk factors of Kaposi sarcoma:

Certain ethnicities: Jewish, of Mediterranean descent, and equatorial Africans.

Sex: Men are at higher risk of developing Kaposi sarcoma.

Human herpesvirus 8 (HHV-8): Most people with HHV-8 don't develop Kaposi sarcoma, but those with immune system problems are more susceptible.

Immune deficiency: People with HIV/AIDS or those with suppressed immune systems after organ transplantation.

Sexual activity: Unprotected sexual activity increases the risk of HHV-8 and HIV infections.³

What can I expect if I have kaposi sarcoma?

• Painless discoloured patches on the skin or inside the mouth.
• Patches may grow into lumps and merge.’
• Lymph nodes, lungs, and digestive systems can be affected.
• Symptoms include uncomfortable swelling, breathlessness, coughing up blood, chest pain, nausea, vomiting, stomach pain, and diarrhoea.
• Progression speed varies depending on the type of Kaposi's sarcoma; without treatment, most types worsen quickly in weeks or months.⁴

When should I see a doctor?

You should see a healthcare provider if:

• You have symptoms that you suspect to be caused by Kaposi's sarcoma or;
• Your diagnosed Kaposi's sarcoma symptoms worsen or;
• You have previously had Kaposi's sarcoma, and it has returned.
• If you have HIV, contact a local HIV clinic for concerns about Kaposi sarcoma.⁴

Summary

Kaposi sarcoma is a cancer affecting blood and lymph vessels, manifesting purplish lesions on the skin, legs, face, genitals, mouth, lymph nodes, digestive tract, and lungs. Its primary cause is human herpesvirus 8 (HHV-8) infection. Those with weakened immune systems, like HIV/AIDS or organ transplant patients, face a higher risk. 

Different types of Kaposi sarcoma include epidemic (AIDS-related), iatrogenic (linked to immunosuppressant treatment), classic, and endemic. Symptoms differ based on the type and may encompass skin lesions, lymphedema, gastrointestinal and oral lesions, lung involvement, and lymph node swelling. Diagnosis necessitates a biopsy and further tests to detect internal Kaposi sarcoma.

Treatment aims to ease symptoms and slow disease progression. This includes local treatments (radiotherapy), systemic chemotherapy, antiretroviral therapy, reduced immunosuppression, and participation in clinical trials. There is currently no vaccine or primary prevention specifically for Kaposi sarcoma, but practising HIV prevention measures can be beneficial. While incidence has diminished with antiretroviral therapy, Kaposi sarcoma remains more prevalent in specific demographics and in those with HIV/AIDS or compromised immune systems. If you experience symptoms or have concerns, seeking medical attention, especially if you have HIV, is advised.