Kaposi Sarcoma: A Comprehensive Overview**

**Definition and Epidemiology**

Kaposi sarcoma (KS) is a rare, malignant vascular tumor caused by human herpesvirus 8 (HHV-8) infection. It primarily affects individuals with compromised immune systems, particularly those living with HIV/AIDS. There are four main variants:

1. **Classic KS**: Affects older adults, typically of Mediterranean or Eastern European descent, with a slow-growing, indolent course.
2. **Epidemic KS** (AIDS-associated KS): The most common form, linked to HIV infection, with rapid progression and widespread dissemination.
3. **Iatrogenic KS**: Associated with immunosuppressive therapy, particularly in solid-organ transplant recipients.
4. **Endemic KS**: Found in certain African regions, affecting both HIV-positive and HIV-negative individuals.

**Clinical Presentation**

* **Cutaneous lesions**: Characteristic purple, red, or brown macules, patches, or nodules, often on the lower extremities, face, and mucous membranes.
* **Visceral involvement**: Commonly affects lymph nodes, gastrointestinal tract, lungs, and liver, leading to symptoms like:
+ Gastrointestinal bleeding or obstruction
+ Respiratory distress or coughing up blood
+ Lymphedema or swelling

**Diagnosis and Staging**

1. **Biopsy**: Confirmatory diagnosis through histopathological examination of lesional tissue.
2. **Imaging**: CT, MRI, or PET scans to assess extent of visceral involvement.
3. **Staging**: Tumor burden, immune status, and systemic illness guide prognosis and treatment:
* **Good-risk** (localized, high CD4+ count, low HIV viral load)
* **Poor-risk** (widespread, low CD4+, high viral load, systemic symptoms)

**Treatment and Management**

1. **Antiretroviral therapy (ART)**: Crucial for HIV-associated KS, improving immune function and reducing tumor burden.
2. **Chemotherapy**: Liposomal anthracyclines (e.g., doxorubicin), taxanes, or paclitaxel for advanced or refractory disease.
3. **Targeted therapies**: Inhibitors of angiogenesis (e.g., bevacizumab) or mTOR signaling (e.g., sirolimus) show promise.
4. **Local therapies**: Radiation, cryotherapy, or surgical excision for limited, symptomatic lesions.
5. **Supportive care**: Managing pain, lymphedema, and comorbidities.

**Prognosis and Prevention**

* **Prognosis**: Variable, dependent on KS variant, immune status, and treatment response. Overall 5-year survival: 50-70%.
* **Prevention**: Effective ART, safe sex practices, and HHV-8 screening in high-risk populations (e.g., transplant candidates) can reduce incidence.

**Key Takeaways**

* Kaposi sarcoma is a complex, HHV-8-driven malignancy, predominantly affecting immunocompromised individuals.
* Accurate diagnosis, staging, and tailored treatment (ART, chemotherapy, targeted therapies, and local approaches) improve outcomes.
* Early detection, immune restoration, and prevention strategies are crucial for optimal management and reducing disease burden. Multidisciplinary care, integrating oncology, infectious disease, and dermatology expertise, is essential for delivering comprehensive care to KS patients.