(See also Overview of Skin Cancer Overview of Skin Cancer Skin cancer is the most common type of cancer and commonly develops in sun-exposed areas of skin. The incidence is highest among outdoor workers, sportsmen, and sunbathers and is inversely related... read more .)
Kaposi sarcoma originates from endothelial cells in response to infection by human herpesvirus type 8 Herpesviruses That Infect Humans Eight types of herpesviruses infect humans (see Table: Herpesviruses That Infect Humans). After initial infection, all herpesviruses remain latent within specific host cells and may subsequently... read more (HHV-8). Immunosuppression (particularly by AIDS and drugs for organ transplant recipients) markedly increases the likelihood of Kaposi sarcoma in HHV-8–infected patients. The tumor cells have a spindle shape, resembling smooth muscle cells, fibroblasts, and myofibroblasts.
Classification of Kaposi Sarcoma
Classic Kaposi sarcoma
This form occurs most often in older (> 60 years) 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 Kaposi sarcoma (epidemic Kaposi sarcoma)
This form is the most common AIDS-associated cancer Cancers Common in HIV-Infected Patients AIDS-defining cancers in HIV-infected patients are Kaposi sarcoma Lymphoma, Burkitt (or equivalent term) Lymphoma, immunoblastic (or equivalent term) Lymphoma, primary, of central nervous system read more and is more aggressive than classic Kaposi sarcoma. Multiple cutaneous lesions are typically present, often involving the face and trunk. Mucosal, lymph node, and gastrointestinal (GI) involvement is common. Sometimes Kaposi sarcoma is the first manifestation of AIDS.
Endemic Kaposi sarcoma
This form occurs in Africa independent of HIV infection. There are 2 main types:
Prepubertal lymphadenopathic form: It predominantly affects children; primary tumors involve lymph nodes, with or without skin lesions. The course is usually fulminant and fatal.
Adult form: This form resembles classic Kaposi sarcoma.
Iatrogenic Kaposi sarcoma (immunosuppressive Kaposi sarcoma)
This form typically develops several years after organ transplantation. The course is more or less fulminant, depending on the degree of immunosuppression.
Symptoms and Signs of Kaposi Sarcoma
Cutaneous lesions are asymptomatic purple, pink, or red macules that may coalesce into blue-violet to black plaques and nodules. Some edema may be present. Occasionally, nodules fungate or penetrate soft tissue and invade bone. Although less common, visceral involvement most often involves the oral cavity, gastrointestinal tract, and the lungs. Symptoms depend on specific organ involvement. Mucosal lesions appear as bluish to violaceous macules, plaques, and tumors. GI lesions can bleed, sometimes extensively, but usually are asymptomatic.
Diagnosis of Kaposi Sarcoma
Diagnosis of Kaposi sarcoma is confirmed by punch biopsy.
Patients with AIDS or immunosuppression require evaluation for visceral spread by CT of the chest and abdomen. If CT is negative but pulmonary or gastrointestinal (GI) symptoms are present, bronchoscopy or GI endoscopy should be considered.
Treatment of Kaposi Sarcoma
Surgical excision, cryotherapy, electrocoagulation, intralesional chemotherapy, or possibly topical imiquimod for superficial lesions
Local radiation therapy and chemotherapy for multiple lesions, diffuse involvement, or lymph node disease
Antiretroviral therapy with similar local treatments or chemotherapy depending on extent of disease for AIDS-associated Kaposi sarcoma
Reduction of immunosuppressants for iatrogenic Kaposi sarcoma
Treatments for classic and AIDS-associated Kaposi sarcoma overlap considerably.
Indolent lesions often require no treatment. One or a few superficial lesions can be removed by excision, cryotherapy, or electrocoagulation or treated with intralesional vinblastine or interferon alfa. Topical imiquimod has also been reported to be effective. Multiple lesions, diffuse involvement, and lymph node disease are treated locally with 10 to 20 Gy of radiation therapy and chemotherapy. Recurrence is common, and it is difficult to obtain a complete cure.
AIDS-associated Kaposi sarcoma responds markedly to highly active antiretroviral therapy (HAART), probably because the CD4+ count improves and the HIV viral load decreases; however, there is some evidence that protease inhibitors in this regimen may block angiogenesis. In AIDS patients with indolent local disease who have CD4+ counts > 150/mcL and HIV RNA < 500 copies/mL, intralesional vinblastine can be added. Pomalidomide can also be used for more indolent lesions. Patients with more extensive or visceral disease can be given pegylated liposomal doxorubicin 20 mg/m2 IV every 2 to 3 weeks. Paclitaxel is an alternative first-line treatment or can be given if pegylated liposomal doxorubicin fails. Other agents being investigated as adjuncts include interleukin (IL)-12, desferrioxamine, and oral retinoids. Treatment of Kaposi sarcoma does not prolong life in most AIDS patients because infections dominate the clinical course.
Iatrogenic Kaposi sarcoma responds best to stopping immunosuppressants. In organ transplant patients, reduction of immunosuppressant dosage often results in reduction of Kaposi sarcoma lesions. If dosage reduction is not possible, conventional local and systemic therapies used in other forms of Kaposi sarcoma should be instituted. Sirolimus may also improve iatrogenic Kaposi sarcoma.
Endemic Kaposi sarcoma treatment is challenging and typically palliative.
Consider Kaposi sarcoma in older men, Africans, and patients with organ transplants or AIDS.
Test patients with immunosuppression (including AIDS) for metastases.
Treat superficial lesions with locally ablative methods.
Treat multiple lesions, diffuse involvement, or lymph node disease with local radiation therapy and chemotherapy.