3.3.8 Kaposi’s Sarcoma
Grading & Level of Importance: C
(Sarcoma idiopathicum multiplex haemorrhagicum: old terminology).
Rare disease, more common in HHV-8 endemic areas (Mediterranean, African) and in immunocompromised subjects.
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.
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).
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.
Biopsy is mandatory: proliferation of spindle-cells that stain for endothelial cell markers such as CD34 and CD31. Immunohistochemistry against HHV-8 antigen.
Classic, endemic: rare systemic involvement. Epidemic, iatrogenic: more frequent systemic involvement.
Untreated Kaposi sarcoma can show a local, slow progression. Lymphedema may occur. Visceral involvement (lung, esophagus, colon) may lead to bleeding or breathing difficulties.
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.
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.
Interdisciplinary approach in epidemic forms of disseminated Kaposi sarcoma.
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