Kaposi’s Sarcoma

Synonyms

(Sarcoma idiopathicum multiplex haemorrhagicum: old terminology).

Epidemiology

Rare disease, more common in HHV-8 endemic areas (Mediterranean, African) and in immunocompromised subjects.

Definition

Multifocal neoplasm of spindle-shaped lymphatic-endothelium-derived cells infected with HHV-8 (human herpes virus 8).

Aetiology & Pathogenesis

Kaposi’s sarcoma is associated with HHV-8 infection. Immunosuppression is a well-known risk factor (HIV and transplantation).

Signs & Symptoms

Blue-red (purple) macules, plaques or tumours on the skin and mucosae +/- lymphoedema.

Localisation

Classic Kaposi’s sarcoma typically begins as nodules of the legs and has a slow progression. In immunosuppressed patients disseminated macules are frequently found on the skin and mucous membranes, along with involvement of lymph nodes, gastrointestinal- or respiratory tract (lungs).

Classification

Kaposi’s sarcoma is classified into four types: classic Kaposi’s sarcoma (older men in southeastern Europe and the Mediterranean basin), endemic (African) Kaposi’s sarcoma, HIV-associated (epidemic) Kaposi’s sarcoma. Kaposi’s sarcoma in immunosuppressed patients (iatrogenic) may occur for example in solid organ transplant recipients.

Laboratory & other workups

HIV serology and standard blood tests in all cases. HHV-8 viraemia and CD4 T cell count in epidemic (HIV) and iatrogenic forms.

Dermatopathology

Biopsy is mandatory: proliferation of spindle-cells that stain for endothelial cell markers such as CD34 and CD31. Immunohistochemistry against HHV-8 antigen.

Course

Classic, endemic: rare systemic involvement. Epidemic, iatrogenic: more frequent systemic involvement.

Complications

Untreated Kaposi sarcoma can show a local, slow progression. Lymphedema may occur. Visceral involvement (lung, esophagus, colon) may lead to bleeding or breathing difficulties.

Diagnosis

Clinical features, histology, and detection of HHV-8. A total body CT scan +/- lung and digestive endoscopies can be performed depending on the clinical form.

Differential diagnosis

Benign and malignant vascular tumours (angiosarcomas/lymphangiosarcomas), bacillary angiomatosis, T and B-cell lymphomas, pseudo-Kaposi’s sarcoma (acroangiodermatitis), described in more detail in chapter 8.9 on “Eruptive Angiomatous Lesions”.

Pseudo-Kaposi-Sarcoma (Acroangiodermatitis Mali) is a reactive process. It presents as red brown (hemosiderin deposits) plaques on the back of the toes or on the ankle in patients with chronic venous insufficiency. Histology reveals the feature of stasis dermatitis with fibrosis and grouped capillary vessels.

Prevention & Therapy

Reduction of the immunosuppression in epidemic (antiretroviral therapy) and iatrogenic (reduction of immunosuppressants, switch to mTOR inhibitors) forms. In classic Kaposi sarcoma, no treatment is needed in many cases. Surgery or laser may be used to destroy lesions. Radiotherapy, intralesional chemotherapies and electrochemotherapy. Topical treatments such as imiquimod. Systemic treatments are reserved for locally aggressive extensive and disseminated Kaposi sarcoma: pegylated liposomal doxorubicin, paclitaxel, pegylated interferon.

Special

Interdisciplinary approach in epidemic forms of disseminated Kaposi sarcoma.

3.3.8 Kaposi’s Sarcoma