Epidemiology

Most common malignancy in patients with untreated HIV

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Etiology

• Caused by human herpesvirus 8 (HHV8), a large DNA gamma herpes virus
• Routes of transmission include
  • Saliva
  • Sexual contact
  • Potentially via blood transfusion and IV drug use

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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

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Clinical features

Patients typically present with multiple cutaneous or visceral elevated tumors with rapid growth.

• Most commonly affects the skin but may also involve the lymph nodes, mucosa, and viscera
• Can occur at any CD4 count (typically < 500/mm3)
• Initial stage:
  • Painless, nonpruritic, violet papules or nodules on skin and mucosa (especially face/oral cavity and chest)
  • Solitary, darkly pigmented plaques, which can evolve into nodular, bluish, submucosal, and painful skin changes
  • Lesions resemble those of bacillary angiomatosis.
• 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
  • Pulmonary involvement: Lesions cause dyspnea, cough, and/or hemoptysis.

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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.

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Treatment

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