Kaposi sarcoma !
Kaposi sarcoma is a cancer of blood and lymphatic vessel cells caused by a herpesvirus, seen mostly in people with HIV, causing purple skin spots.
Updated 2026-11-01
Structures involved
Tap one to see what it is and open it in 3D.
Microorganisms that cause it
Why it happens
- Tumour angiogenesis
- Evading cell death and replicating without limit: BCL2 and telomerase
- How tumours evade the immune system
- Oncogenic viruses and H. pylori: the table to know
- Blood vessels: artery, vein and capillary layers
What it is
A low-grade vascular tumour of lymphatic endothelial origin caused by human herpesvirus 8 (HHV-8, Kaposi sarcoma-associated herpesvirus). It produces purple, red or brown macules, plaques and nodules on the skin and mucosa and can involve lymph nodes, the gut and the lungs. Kaposi sarcoma is an AIDS-defining illness.
Who gets it
The most common HIV-associated cancer worldwide, especially in men who have sex with men with low CD4 counts. In Colombia and Latin America it is seen mainly in people with late HIV diagnosis or poor adherence to antiretroviral therapy. Classic disease affects older men of Mediterranean or Jewish ancestry, endemic disease occurs in sub-Saharan Africa, and iatrogenic disease follows organ transplantation.
Causes
- Infection with HHV-8, transmitted mainly through saliva and also sexually, by blood and by transplanted organs
- Immunosuppression that allows the virus to drive tumour growth (HIV, transplant drugs, corticosteroids)
Risk factors
- HIV infection with low CD4 count or uncontrolled viral load
- Men who have sex with men
- Organ transplantation and immunosuppressive treatment
- Older age and Mediterranean ancestry (classic type)
- Living in sub-Saharan Africa (endemic type)
Pathophysiology
HHV-8 infects endothelial cells and expresses viral proteins that mimic cell cyclins, block apoptosis (viral FLIP, LANA inhibiting p53) and activate angiogenic signalling (viral G-protein-coupled receptor, VEGF). Infected spindle cells form slit-like vascular spaces with red cell extravasation and haemosiderin, which gives lesions their purple colour. Immune suppression removes T-cell control of the virus.
Classification
- Classic (indolent, older men, lower legs)
- Endemic (African, including aggressive childhood lymphadenopathic form)
- Iatrogenic (transplant-associated, may regress when immunosuppression is reduced)
- Epidemic or AIDS-associated (the most aggressive and widespread)
Symptoms and signs
- Painless purple, red-brown or violaceous macules, plaques or nodules that do not blanch
- Common sites: lower legs and feet, face, nose, genitals and oral cavity (hard palate and gums)
- Lymphoedema of the legs, genitals or face
- Gastrointestinal involvement: often silent, or bleeding, pain or obstruction
- Pulmonary involvement: cough, breathlessness, haemoptysis, pleural effusion
Diagnosis
- Clinical
- Suspected from typical violaceous lesions, especially in a person with HIV; the oral cavity, especially the palate, must always be examined.
- Tests
- Skin or mucosal biopsy is required: spindle cells, slit-like vessels, extravasated red cells and positive immunostaining for HHV-8 latency-associated nuclear antigen (LANA). HIV test, CD4 count and viral load in every patient. Stool occult blood and endoscopy when gastrointestinal disease is suspected.
- Imaging
- Chest X-ray or CT for respiratory symptoms; bronchoscopy shows red-purple mucosal lesions (biopsy carries bleeding risk). Imaging guides staging of visceral disease.
Differential diagnosis
- Bacillary angiomatosis (Bartonella; responds to antibiotics)
- Pyogenic granuloma and haemangiomas
- Melanoma and other pigmented tumours
- Stasis dermatitis and acroangiodermatitis
- Angiosarcoma and other vascular tumours
Goal of treatment
Restore immune function, control symptomatic or visceral disease, and relieve lymphoedema and cosmetic burden; in AIDS-associated disease, effective antiretroviral therapy is the foundation.
Treatment
- Medical
- Antiretroviral therapy for every person with HIV-associated Kaposi sarcoma; it alone controls many limited cases. In transplant patients, immunosuppression is reduced and switching to an mTOR inhibitor (sirolimus) may help.
- Medical
- Systemic chemotherapy for advanced, visceral or rapidly progressive disease: liposomal doxorubicin or paclitaxel are first-line; immunomodulators such as pomalidomide are options in refractory disease.
- Procedure
- Local therapy for limited lesions: radiotherapy, intralesional vinblastine, cryotherapy, topical alitretinoin or surgical excision.
- Follow-up
- CD4 count and viral load, watch for immune reconstitution flares, prophylaxis of opportunistic infections, and lymphoedema care.
Drugs for this condition
Complications
- Gastrointestinal bleeding or obstruction
- Respiratory failure and haemorrhage from pulmonary disease
- Lymphoedema and secondary infection
- Immune reconstitution inflammatory syndrome after starting antiretrovirals
- Associated HHV-8 diseases: primary effusion lymphoma and multicentric Castleman disease
Prognosis
Classic disease is indolent over decades. With antiretroviral therapy, AIDS-associated disease has a much better outlook, but pulmonary involvement and low CD4 counts carry a worse prognosis.
Prevention
- Early HIV diagnosis and sustained antiretroviral therapy
- Safer sex practices
- Careful management of immunosuppression in transplant recipients
Test yourself
Think of the answer, then tap the question to see it.
Which virus causes Kaposi sarcoma?
Human herpesvirus 8 (HHV-8, Kaposi sarcoma-associated herpesvirus).
What is the first step in treating AIDS-associated Kaposi sarcoma?
Start or optimise antiretroviral therapy.
Which oral site should always be examined in someone with HIV and suspected Kaposi sarcoma?
The hard palate (and gums).
Which infectious lesion mimics Kaposi sarcoma in HIV and responds to antibiotics?
Bacillary angiomatosis caused by Bartonella.
Which two other diseases are caused by HHV-8?
Primary effusion lymphoma and multicentric Castleman disease.
Related conditions
- HIV infection and AIDS
- Pneumocystis pneumonia (PCP)
- Lymphoedema
- Upper gastrointestinal bleeding
- Bartonella infections (cat-scratch disease, Carrion disease)
- Melanoma
Educational information, not medical advice. For any symptom, see a health professional.
Sources: Kaposi sarcoma (MedlinePlus, US National Library of Medicine, 2026).
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Representative model, for educational purposes only.
