Kaposi sarcoma

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Kaposi sarcoma is a malignant, multifocal, highly vascularized tumor of the endothelial cells that most commonly affects the skin but may also involve the lymph nodes, mucosa, and viscera. It is commonly associated with HIV and can occur at any CD4 count (typically < 500/mm³). Diagnosis is confirmed with biopsy. Treatment depends on whether the disease is localized or disseminated; all patients with HIV should be started on ART.

• Caused by human herpesvirus 8 (HHV8), a large DNA gamma herpes virus
• Routes of transmission include ^[2]
  • Saliva
  • Sexual contact
  • Potentially via blood transfusion and IV drug use

Patients typically present with multiple cutaneous or visceral elevated tumors with rapid growth. ^[2][3]

• 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.

Cutaneous lesions are the typical initial manifestation of KS. However, extracutaneous lesions (disseminated disease) can precede skin involvement. ^[4]

Lesions resemble those of bacillary angiomatosis and histology is required to differentiate between the conditions.

• HIV/AIDS-associated KS (epidemic KS):
  • Most common HIV-associated tumor disease
  • Commonly manifests as multiple cutaneous lesions on the face, limbs, and torso
• Classic KS; : usually occurs in older Mediterranean or Eastern European men
• Iatrogenic KS; : usually occurs in immunosuppressed patients after organ transplants
• Endemic KS
  • Most commonly occurs in Sub-Saharan Africa in HIV-uninfected individuals
  • Aggressive disease with lymph node and visceral involvement is common in children

References: ^[2][3][5]

• HIV screening
• Biopsy and histology of cutaneous or visceral lesions (indicated in all patients)
  • Spindle shaped cells, leukocyte infiltration, and angiogenesis
  • Immunostaining helps differentiate KS from other similar diagnoses (e.g., bacillary angiomatosis)
• CT with IV contrast: contrast-enhancement of lesions ^[6]
  • Chest: diffuse reticulonodular infiltrates, pleural effusion, peribronchovascular nodules
  • Abdomen/pelvis: hepatomegaly, multifocal liver nodules with contrast-enhancement, bowel wall thickening, lymphadenopathy
  • Lytic bony lesions and soft tissue masses may also be seen.
• Additional studies (depending on symptoms): Endoscopy and bronchoscopy may show red-purple lesions; hemorrhage may also be visible.

References: ^[2][3][5]

The decision to treat depends on whether the disease is localized or disseminated, as well as whether there is any underlying immunosuppression.

• Immunosuppressed patients: Manage underlying immunosuppression (first-line treatment).
  • HIV-associated KS: Start ART. ^[2]
  • Chemotherapy (liposomal doxorubicin and paclitaxel): indicated for systemic disease; consider for disseminated cutaneous disease.
  • If feasible, reduce doses of, or change, immunosuppressive medications.
• Immunocompetent patients or inadequate response to first-line therapy for immunosuppressed patients
  • Localized disease: intralesional chemotherapy , cryotherapy, radiation therapy, or laser therapy
  • Systemic disease
    • Systemic chemotherapy with liposomal anthracyclines or paclitaxel
    • α-interferon

References: ^[2][3][5]

Prognosis is variable, depending on subtype and whether disease is localized or systemic ^[3][7][8]