Epidemiology
Most common malignancy in patients with untreated HIV
Etiology
- Caused by human herpesvirus 8 (HHV-8), a large DNA gamma herpes virus
- Routes of transmission include
- Saliva
- Sexual contact
- Potentially via blood transfusion and IV drug use
Pathophysiology
HHV-8 infects vascular and lymphatic endothelial cells, causing them to differentiate into a mixed phenotype thought to increase oncogenic potential. The HHV-8 genome contains several viral oncogenes that inhibit cell cycle regulation and apoptosis, thereby promoting endothelial cell growth and tumorigenesis
Clinical features
- Cutaneous Lesions:
- Violaceous (purplish-red to dark brown) macules, papules, plaques, or nodules.
- Non-tender, non-pruritic, non-blanching.
- Common sites: Lower extremities, trunk, face, mucosal surfaces (hard palate, gingiva).
- Progression: may disseminate to the organs, particularly the gastrointestinal tract, respiratory tract, and lymph nodes.
- Gastrointestinal tract involvement: abdominal pain and diarrhea; hemorrhage and bowel obstruction in severe cases
- Often polypoid nodules
- Often polypoid nodules
- Pulmonary: Dyspnea, cough, hemoptysis, fever. CXR shows bilateral interstitial infiltrates and pleural effusions (poor prognosis).
- Gastrointestinal tract involvement: abdominal pain and diarrhea; hemorrhage and bowel obstruction in severe cases
Diagnostics
- Biopsy and histology of cutaneous or visceral lesions (indicated in all patients)
- Dermal proliferation of spindle-shaped endothelial cells with slit-like vascular spaces, red blood cell extravasation, and inflammation.
- Dermal proliferation of spindle-shaped endothelial cells with slit-like vascular spaces, red blood cell extravasation, and inflammation.
| Feature | Bacillary Angiomatosis (BA) | Kaposi Sarcoma (KS) |
|---|---|---|
| Etiology | Bartonella spp. (Bacteria) | HHV-8 (DNA Virus) |
| Histology | Capillary proliferation, plump endothelial cells | Spindle cells, slit-like vascular spaces |
| Infiltrate | Neutrophilic | Lymphocytic & Plasmacytic |
| Special Stain | Warthin-Starry stain shows organisms | N/A |
| Treatment | Antibiotics (Doxycycline, Erythromycin) | ART (first-line), Chemotherapy/Radiation for severe disease |
Treatment
- Systemic Antiretroviral Therapy (ART):
- First-line treatment for all AIDS-related cases. Immune reconstitution often causes regression of cutaneous lesions.
- Systemic Chemotherapy:
- Indicated for extensive cutaneous disease, visceral involvement (GI/pulmonary), or progression despite ART.
- First-line agents: Liposomal doxorubicin or paclitaxel.
- Local Therapy (Symptomatic or cosmetic lesions only):
- Intralesional vinblastine, topical alitretinoin, radiation therapy, or cryotherapy.
- Transplant-related KS:
- Reduce immunosuppressive therapy (e.g., transition to mTOR inhibitors like sirolimus).