Kaposi sarcoma (KS) is an endothelial neoplasm that usually occurs as skin or oral lesions but may involve the internal organs. It is the most common AIDS-associated neoplasm and is an AIDS-defining disease. AIDS-associated KS is one of four types of KS, along with classic, endemic, and organ transplant-associated KS. Although the types vary in epidemiology and clinical presentation, all are associated with human herpesvirus type 8 (HHV-8), also known as KS-associated herpesvirus. The clinical manifestations of AIDS-associated KS (sometimes called epidemic KS) range in severity from mild to life-threatening. The progression of disease may be rapid or slow, but the overall prognosis is poor in the absence of treatment. The skin lesions of KS, even when they do not cause medical morbidity, may cause significant disfigurement and emotional distress.
AIDS-associated KS usually occurs in HIV-infected persons with advanced immunosuppression (CD4 count of <200 cells/µL), but may occur at any CD4 count. In the United States and Europe, KS occurs in all HIV risk groups, but most frequently among men who have sex with men (MSM). Risk factors for MSM include multiple sexual partners and a history of sexually transmitted infections (STIs); risk factors for other groups have not been clearly identified. The transmission of HHV-8 is not well understood. Although experts believe HHV-8 is transmitted sexually, it apparently also passes from person to person by other routes.
The incidence of KS in resource-abundant countries has declined markedly since the early 1990s, in part because of the widespread availability of effective combination antiretroviral therapy (ART). In parts of sub-Saharan Africa, where endemic KS has long existed in people with normal immune function, the incidence of KS has risen sharply in people with HIV. ART appears to be effective in reducing the risk of AIDS-associated KS, particularly when initiated before the development of advanced immunosuppression.
The cutaneous presentation of KS is the most common, occurring in 95% of cases. Lesions may occur anywhere on the skin. Common sites include the face (particularly under the eyes and on the tip of the nose), behind the ears, and on the extremities and torso. Lesions may be macules, papules, plaques, or nodules. At first, the lesions are small and may be flat. Their color may vary from pink or red to purple or brown-black (the latter particularly in dark-skinned individuals), and they are nonblanching, nonpruritic, and painless (lesions may become painful in the setting of immune reconstitution inflammatory syndrome [IRIS] associated with KS). Over time, the lesions often increase in size and number, darken, and rise from the surface; they may progress to tumor plaques (e.g., on the thighs or soles of the feet), or to exophytic tumor masses, which can cause bleeding, necrosis, and extreme pain.
Oral lesions may be flat or nodular and are red or purplish. They usually appear on the hard palate, but may develop on the soft palate, gums, tongue, and elsewhere. Oral lesions, if extensive, may cause tooth loss, pain, and ulceration.
Lymphedema associated with KS usually appears in patients with visible cutaneous lesions, and edema may be out of proportion to the extent of visible lesions. Lymphedema also may occur in patients with no visible skin lesions. Common sites include the face, neck, external genitals, and lower extremities. A contiguous area of skin usually is involved. Lymph nodes may be enlarged.
Pulmonary KS may be asymptomatic or cause intractable cough, bronchospasm, hemoptysis, chest pain, and dyspnea. The patient may exhibit difficulty breathing, bronchospasm, cough (sometimes with hemoptysis), and hypoxemia.
Gastrointestinal KS may arise anywhere in the gastrointestinal tract. Patients usually are asymptomatic except in cases of intestinal obstruction or bleeding. KS may cause protein-losing enteropathy. Visceral disease is uncommon in the absence of extensive cutaneous disease.
During the history, ask about the symptoms noted above and associated characteristics, including the following:
Perform a careful physical examination, with particular attention to the following:
Examine the lungs, abdomen, rectum, and other systems as indicated.
The partial differential diagnosis depends on the type of symptoms present.
For cutaneous, oral, and lymph node presentations, consider the following:
For pulmonary symptoms, consider the following:
For cutaneous or oral KS, a presumptive diagnosis often can be made by the appearance of skin or mucous membrane lesions. Biopsy of a lesion (or a suspect lymph node) is strongly recommended to verify the diagnosis and rule out infectious or other neoplastic causes. Biopsy is particularly important if the lesions are unusual in appearance or if the patient has systemic or atypical symptoms.
If respiratory symptoms are present, obtain chest X rays or computed tomography (CT) studies. The chest X ray typically shows diffuse interstitial infiltrates, often accompanied by nodules or pleural effusion. Radiographic findings may be suggestive of KS, but cannot provide a definitive diagnosis. Bronchoscopy with visualization of characteristic endobronchial lesions usually is adequate for diagnosis.
For patients with gastrointestinal symptoms and suspected KS, perform endoscopy.
If the patient has fever or respiratory, gastrointestinal, or constitutional symptoms, evaluate for other infectious and malignant causes (e.g., by culture or biopsy) as suggested by the history and physical examination.
Treatment of KS is not considered curative, and no single therapy is completely efficacious. ART is a key component of the treatment of KS and should be initiated (or optimized to achieve complete HIV RNA suppression) for all persons with KS, unless contraindicated (for further information, see chapter Antiretroviral Therapy). KS often regresses and sometimes resolves in patients treated with effective ART. Some data suggest that protease inhibitors may have an anti-KS effect; however, non-PI-containing regimens also lead to KS regression. The role of specific antiretroviral agents beyond HIV control in KS remains unclear, although some experts prefer to use PIs for patients with active KS.
KS-associated IRIS has been described, and patients may experience painful enlarged lesions or progression of KS lesions during the first months of ART; they should be advised of this possibility.
Specific treatment of KS depends on various factors such as the number, extent, severity, and location of lesions; cosmetic considerations; and presence of visceral involvement. The goals of therapy may vary according to the clinical presentation and may include controlling symptoms, improving cosmetic appearance, reducing edema, eliminating pain, and clearing lesions. Local treatment (preferably in conjunction with ART) usually is given to patients who have a few small lesions causing only minor symptoms. Systemic therapy (in conjunction with ART) is needed for more extensive or more severe disease, including symptomatic visceral disease, widespread skin involvement, significant edema, and rapidly progressive KS. Consultation with a KS-experienced oncologist or dermatologist is recommended.
Options for local treatment of limited disease include the following:
Extensive or rapidly progressing disease may include lymphedema, intraoral or pharyngeal disease that interferes with eating, painful or bulky lesions, and symptomatic pulmonary or visceral disease. Options for treatment include the following: