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Kaposi's
sarcoma is a multicentric vascular tumor caused by herpesvirus type
8. It can occur in AIDS-associated, endemic, and iatrogenic forms.
Diagnosis is by biopsy. Treatment for indolent superficial lesions
involves cryotherapy, electrocoagulation, or electron beam radiation therapy.
Radiation therapy is used for more extensive disease. In the AIDS-associated
form, antiretrovirals provide the best improvement
Kaposi's sarcoma (KS) originates from endothelial cells in response to infection by human herpesvirus 8 (HHV-8). Immunosuppression (particularly by AIDS and drugs for organ transplant recipients) markedly increases the likelihood of KS in HHV-8–infected patients. The tumor cells have a spindle shape, resembling smooth muscle cells, fibroblasts, and myofibroblasts.
Classic KS occurs most often in older (> 60 yr) men of Italian, Jewish, or Eastern European ancestry. The course is indolent, and the disease is usually confined to a small number of lesions on the skin of the lower extremities; visceral involvement occurs in < 10%. This form is usually not fatal.
AIDS-associated (epidemic) KS is the most common AIDS-associated malignancy and is more aggressive than classic KS. Multiple cutaneous lesions are typically present, often involving the face and trunk. Mucosal, lymph node, and GI involvement is common. Sometimes KS is the first manifestation of AIDS.
Endemic KS occurs in Africa independent of HIV infection. There are 2 peaks, prepubertal and adult. The prepubertal lymphadenopathic form is more aggressive and usually fatal. The adult form more resembles classic KS.
Iatrogenic (immunosuppressive) KS typically develops several years after organ transplantation. The course is more or less fulminant, depending on the degree of immunosuppression.
The lymphadenopathic type, most common in endemic KS, predominantly affects children with primary tumors involving lymph nodes (with or without skin lesions). The course is usually fulminant and fatal.
Symptoms,
Signs, and Diagnosis
Cutaneous lesions are asymptomatic purple, pink, or red macules that may coalesce into blue-violet to black plaques and eventually nodules. Some edema may be present. Occasionally, nodules fungate or penetrate soft tissue and invade bone. Mucosal lesions appear as bluish to violaceous macules, plaques, and tumors. GI lesions can bleed, sometimes extensively, but usually are asymptomatic.
Diagnosis is confirmed by punch biopsy. Patients with AIDS or immunosuppression require evaluation for visceral spread by CT of the chest and abdomen. If pulmonary or GI symptoms are present, bronchoscopy or GI endoscopy should be considered if CT is negative.
Treatment
Indolent lesions often require no treatment. One or a few superficial lesions can be removed by excision, cryotherapy, or electrocoagulation. Intralesional vinblastine or interferon-α is also useful. Multiple lesions and lymph node disease are treated locally with 10 to 20 Gy of radiation therapy.
AIDS-related KS responds markedly to highly active antiretroviral therapy (HAART); this is probably a result of improvement in CD4+ count and decreasing HIV viral load, but there is some evidence that protease inhibitors in this regimen may block angiogenesis. AIDS patients with indolent disease and CD4+ counts > 150 /μL and HIV RNA < 500 copies/mL can be treated with IV interferon-α. Patients with more extensive or visceral disease can be given liposomal doxorubicin 20 mg/m2 IV q 2 to 3 wk. If this regimen fails, patients may receive paclitaxel . Other agents being investigated as adjuncts include IL-12, HIV-TAT protein inhibitors, and human chorionic gonadotropin. Treatment of KS does not prolong life in most AIDS patients because infections dominate the clinical course.
Iatrogenic KS responds best to stopping immunosuppressants. In organ transplant patients, reduction of immunosuppressant dosage often results in reduction of KS lesions. If this is not possible, conventional local and systemic therapies used in other forms of KS should be instituted.
Last full review/revision November 2005
Content last modified November 2005
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