Kaposi Sarcoma

Content of This Page

1- Introduction

2- Causes

3- Symptoms

4- Types of Kaposi Sarcoma

5- Investigations & Lab Results

6- Complications

7- Treatment

Introduction

Kaposi Sarcoma (KS) is a malignant tumor that arises from endothelial cells lining blood or lymphatic vessels. It is strongly associated with infection by Human Herpesvirus 8 (HHV-8), also known as Kaposi Sarcoma-associated herpesvirus (KSHV).

KS is characterized by the development of vascular tumors that appear as purple, red, or brown patches, plaques, or nodules on the skin, but can also involve mucous membranes, lymph nodes, and internal organs (e.g., lungs and gastrointestinal tract).

© image from Wikimedia Commons

Causes

  • HHV-8 Infection (KSHV):

    • Necessary cause of all forms of KS

    • Transmitted through saliva, sexual contact, blood transfusion, and organ transplantation

    • Virus infects endothelial cells and promotes uncontrolled proliferation and angiogenesis

  • Immunosuppression:

    • Reduces immune surveillance, allowing HHV-8–infected cells to proliferate

    • Common in:

      • HIV/AIDS (especially with low CD4 count)

      • Organ transplant recipients (due to immunosuppressive therapy)

      • Cancer patients on chemotherapy

  • Genetic and Environmental Factors:

    • May contribute in endemic and classic forms

    • Higher prevalence in specific geographic areas (e.g., sub-Saharan Africa, Mediterranean regions)

  • Male Gender:

    • KS is more common in males across all subtypes, though the reasons are not fully understood

© image from Wikimedia Commons

Symptoms

1. Skin Lesions (Most Common Symptom)

  • Color: Pink, red, purple, brown, or dark blue

  • Shape: Macules (flat), papules, plaques, or nodules

  • Texture: May be smooth, raised, or firm

  • Location: Face, legs (especially lower limbs), feet, genital area, and oral mucosa

  • Pattern: May occur singly or in clusters, often symmetric

  • Progression: Lesions may enlarge, coalesce, or ulcerate

2. Mucous Membrane Involvement

  • Lesions on the oral cavity (especially hard palate, gums, or tongue)

  • May cause discomfort, bleeding, or difficulty eating

3. Lymph Node Involvement

  • Painless swelling of lymph nodes

  • Can cause lymphedema (swelling of limbs or face due to lymphatic obstruction)

4. Visceral Involvement (Internal Organs)

Seen mostly in AIDS-associated or immunosuppressed patients:

  • Gastrointestinal tract:

    • Abdominal pain, bleeding, weight loss, or diarrhea

    • May be asymptomatic or detected incidentally

  • Lungs (Pulmonary KS):

    • Shortness of breath, cough, chest pain, or hemoptysis

    • Can be life-threatening

5. Constitutional Symptoms (in advanced disease)

  • Fever

  • Night sweats

  • Weight loss

  • Fatigue

Types of Kaposi Sarcoma

1. Classic Kaposi Sarcoma

  • Population: Elderly men of Mediterranean, Eastern European, or Middle Eastern origin

  • Course: Slow-growing and indolent

  • Lesions: Purple to dark brown skin nodules, mainly on the lower legs and feet

  • Systemic involvement: Rare

  • Prognosis: Generally good; often doesn’t require aggressive treatment

2. Endemic (African) Kaposi Sarcoma

  • Geography: Sub-Saharan Africa

  • Population: Affects both adults and children (particularly prepubertal boys)

  • Course: More aggressive than classic KS

  • Lesions: Extensive skin involvement; may affect lymph nodes and internal organs

  • Prognosis: Variable; can be life-threatening, especially in children

3. Iatrogenic (Immunosuppression-associated) Kaposi Sarcoma

  • Population: Organ transplant recipients or patients on long-term immunosuppressive therapy

  • Trigger: Immunosuppressive medications (e.g., corticosteroids, cyclosporine)

  • Lesions: Skin and mucosal lesions; may involve viscera

  • Prognosis: May regress with reduction of immunosuppressive therapy

4. AIDS-related (Epidemic) Kaposi Sarcoma

  • Population: People living with HIV/AIDS (especially with CD4 counts <200 cells/µL)

  • Course: Aggressive, rapidly progressive

  • Lesions: Widespread skin, mucosal, lymph node, and visceral involvement (lungs, GI tract)

  • Prognosis: Depends on response to antiretroviral therapy (ART) and extent of disease

  • Treatment: Often requires both ART and chemotherapy

Investigations & Lab Results

1. Clinical Examination

  • Careful inspection of skin, oral mucosa, and genital areas for characteristic lesions

  • Palpation for lymphadenopathy or limb swelling (lymphedema)

2. Skin or Lesion Biopsy

  • Gold standard for diagnosis

  • Histopathological findings:

    • Spindle-shaped cells forming vascular slits

    • Extravasated red blood cells

    • Hemosiderin deposition

    • Infiltration with inflammatory cells

  • Immunohistochemistry: Positive for HHV-8 (LANA-1 antigen) in tumor cells

3. Laboratory Tests

  • HIV testing: All patients with suspected KS should be tested for HIV

  • CD4 count and HIV viral load:

    • CD4 count <200 cells/µL common in AIDS-related KS

  • Complete Blood Count (CBC):

    • May show anemia or cytopenias in advanced disease

  • Liver and renal function tests: Baseline before systemic therapy

4. Imaging Studies (to assess visceral involvement)

  • Chest X-ray or CT scan: Evaluate for pulmonary KS (e.g., nodular infiltrates, pleural effusions)

  • Abdominal ultrasound or CT scan: Check for involvement of liver, spleen, or lymph nodes

  • Endoscopy or colonoscopy: For GI symptoms or suspected GI KS (may reveal submucosal nodules or bleeding)

5. Other Investigations (as needed)

  • Bronchoscopy: If pulmonary KS is suspected

  • Lymph node biopsy: If lymphadenopathy is present

  • PCR testing for HHV-8 DNA: Rarely used but available in research or complex cases

Complications

1. Skin and Mucosal Complications

  • Ulceration and secondary infection of lesions

  • Bleeding, especially from oral or mucosal lesions

  • Disfigurement and psychosocial distress

  • Lymphedema due to lymphatic obstruction, often in the legs, genital area, or face

  • Functional impairment, especially if lesions involve eyelids, hands, or joints

2. Pulmonary Involvement

  • Can cause life-threatening respiratory compromise

  • Symptoms: cough, shortness of breath, hemoptysis, chest pain

  • Pleural effusions may develop, leading to breathing difficulty

  • May resemble pneumonia or tuberculosis on imaging

3. Gastrointestinal Involvement

  • Bleeding: May cause melena or hematemesis

  • Obstruction or pain: If large or numerous lesions are present

  • Often asymptomatic, but complications may emerge with progression

4. Lymphatic and Systemic Involvement

  • Generalized lymphadenopathy

  • Severe lymphedema causing chronic swelling and secondary infections

  • Cachexia, fever, night sweats, and weight loss in advanced disease

5. Treatment-Related Complications

  • Chemotherapy toxicity: Myelosuppression, fatigue, nausea

  • Drug interactions with ART or immunosuppressants

  • Immune reconstitution inflammatory syndrome (IRIS): Worsening of KS after starting ART due to recovering immune response

6. Mortality

  • Death may occur due to complications of visceral involvement, particularly pulmonary or gastrointestinal KS, or due to opportunistic infections in immunocompromised patients.

Treatment

Antiretroviral Therapy (ART) – For AIDS-related KS

  • First-line treatment in HIV-positive patients

  • ART alone can lead to regression of KS lesions in early or mild cases

  • May be combined with chemotherapy for extensive or rapidly progressing disease

2. Local Treatments – For limited skin or mucosal disease

  • Cryotherapy: Freezing of superficial lesions

  • Surgical excision: For isolated or cosmetically bothersome lesions

  • Radiation therapy: Effective for localized lesions, particularly in classic or endemic KS

  • Topical agents:

    • Alitretinoin gel (0.1%) – for cutaneous lesions

    • Imiquimod cream – immune response modifier (limited efficacy)

3. Systemic Chemotherapy – For advanced, symptomatic, or visceral disease

  • Indicated for:

    • Rapidly progressing KS

    • Extensive skin involvement

    • Pulmonary, gastrointestinal, or lymphatic KS

    • Poor response to ART alone

Common regimens:

  • Liposomal doxorubicin (preferred due to lower toxicity)

  • Paclitaxel (for refractory or aggressive cases)

  • Vincristine, bleomycin, or etoposide (used in some settings)

4. Immunomodulatory and Targeted Therapies (in specific or refractory cases)

  • Interferon-alpha: For early-stage disease with good immune function (less used now)

  • Immune checkpoint inhibitors (e.g., nivolumab): Under investigation for advanced or recurrent KS

  • Thalidomide or lenalidomide: Occasionally used in difficult-to-treat cases

5. Management of Iatrogenic KS (post-transplant)

  • Reduce or adjust immunosuppressive therapy when possible

  • Switch to mTOR inhibitors (e.g., sirolimus), which may help control KS while maintaining graft function

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