Kaposi Sarcoma
A cancer caused by a virus (HHV-8) that produces purple skin lesions and affects internal organs, mostly in people with weakened immune systems like advanced HIV.
Emergency Management: Acute respiratory failure secondary to massive pulmonary KS hemorrhage or effusion, requiring emergent intubation, bronchoscopy, and urgent systemic chemotherapy.
Kaposi Sarcoma (KS) is a vascular endothelial malignancy caused by human herpesvirus 8 (HHV-8), characterized by multifocal violaceous cutaneous lesions, often with visceral and mucosal involvement.
Detailed Overview
It predominantly affects immunosuppressed individuals, most notably in the setting of advanced HIV/AIDS (Epidemic KS), but also occurs in solid organ transplant recipients (Iatrogenic KS) and classically in older men of Mediterranean/Eastern European descent (Classic KS). HHV-8 infection promotes massive angiogenesis and spindle cell proliferation.
Epidemiology & Demographics
Epidemic (AIDS-related) KS was historically the most common cancer in HIV patients. With modern antiretroviral therapy (ART), incidence has plummeted. Endemic KS is found in Sub-Saharan Africa. Classic KS is rare and indolent in older men.
Etiological Mechanism
Infection with Human Herpesvirus 8 (HHV-8), also known as Kaposi Sarcoma-associated Herpesvirus (KSHV), combined with immune dysfunction.
Primary Causes
HHV-8 infection (necessary but not sufficient on its own)
Profound immunosuppression (HIV/AIDS, CD4 count < 200)
Immunosuppressive medications (Post-transplant)
HHV-8 targets endothelial cells. In the setting of impaired T-cell immunity, the virus expresses latent genes (e.g., LANA) and lytic genes that inhibit apoptosis, evade the immune system, and profoundly stimulate angiogenesis (via VEGF and inflammatory cytokines). This leads to the proliferation of abnormal, spindle-shaped endothelial cells forming slit-like vascular channels filled with red blood cells, resulting in the characteristic highly vascular, purple-red tumors.
Diagnostic Criteria & Guidelines
Clinical appearance confirmed by skin biopsy showing spindle cell proliferation, slit-like vascular spaces, extravasated RBCs, and positive immunohistochemical staining for HHV-8 LANA.
For Epidemic (AIDS-related) KS: 1. Initiation or optimization of Antiretroviral Therapy (ART) is the absolute cornerstone of treatment. Many mild cases resolve completely with immune reconstitution alone. 2. For local, symptomatic skin lesions: Intralesional chemotherapy (vinblastine), topical alitretinoin, or cryotherapy.
Second-Line & Adjunctive Therapy
For severe, rapidly progressive, or visceral KS: Systemic chemotherapy. Liposomal anthracyclines (Pegylated liposomal doxorubicin 20 mg/m2 IV every 3 weeks) are the standard of care. Paclitaxel is an alternative.
Surgical & Procedural Management
Surgery is rarely indicated due to the multifocal nature of the disease, but simple excision may be used for solitary annoying lesions.
Patient Counseling & Advice
Warn patients starting ART that their lesions might temporarily get worse, swell, and become painful before they get better (IRIS phenomenon). Assure them this is a sign the immune system is waking up.
Follow-Up & Monitoring Schedule
Monitor CD4 and HIV viral loads every 3-4 months. Regular physical exams to monitor the size and number of lesions. Monitor cardiac function (ECHO) if taking liposomal doxorubicin.
Preventive Strategies
Safe sex practices to prevent HIV and HHV-8 transmission. Early initiation of ART for all HIV-positive individuals prevents the profound immunosuppression needed for KS to develop.
Highly dependent on immune status. With modern ART, the prognosis for Epidemic KS is generally good. Pulmonary KS remains a severe condition with significant mortality.