Kaposi Sarcoma Workup

Updated: Feb 15, 2022
  • Author: Jessica Katz, MD, PhD; Chief Editor: Edwin Choy, MD, PhD  more...
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Laboratory Studies

All patients who present with Kaposi sarcoma should be evaluated for underlying immunodeficiency and undergo HIV screening. CD4 lymphocyte counts and plasma HIV viral-load studies should be performed for patients with known HIV infection. Patients with AIDS-associated Kaposi sarcoma should also have fecal occult blood testing to screen for possible gastrointestinal involvement. [73] This usually is not necessary for patients with less aggressive forms of Kaposi sarcoma, in which visceral involvement is uncommon.

Patients with Kaposi sarcoma who present with unexplained fevers should undergo additional workup to assess for other human herpes virus 8 (HHV-8)–associated disease, including multicentric Castleman disease or Kaposi sarcoma herpes virus (KSHV)–associated inflammatory cytokine syndrome.

Recommended laboratory tests include the following [74] ;

  • C-reactive protein
  • KSHV/HHV-8 viral load
  • Serum protein electrophoresis (SPEP)
  • Interleukin-6 (IL-6) or IL-10

Imaging Studies

Chest radiographs

Chest x-ray is recommended in all patients with AIDS-associated Kaposi sarcoma to assess for pulmonary involvement. Radiographic findings in Kaposi sarcoma are variable and nonspecific and may include any of the following:

  • Diffuse reticulonodular infiltrates
  • Interstitial infiltrates
  • Pleural effusions
  • Hilar or mediastinal lymphadenopathy
  • An isolated pulmonary nodule

Thallium or gallium scans

These studies may help to differentiate pulmonary Kaposi sarcoma from infection. Pulmonary Kaposi sarcoma lesions typically demonstrate intense thallium uptake and no gallium uptake, whereas infection is often gallium avid and thallium negative.

This differentiation has become less of an issue in the era of highly active antiretroviral therapy (HAART). Prior to that, with the decreasing incidence of Pneumocystis jirovecii pneumonia (PCP), there had been an increased incidence of tuberculosis (TB), Mycobacterium avium-intracellulare (MAI), Kaposi sarcoma, and malignant lymphoma.

In a study performed in the mid 1990s, thallium-positive and gallium-negative pattern of scanning had a sensitivity of 63%, specificity of 95%, positive predictive value of 92%, and negative predictive value of 75%. [75] Presently, this type of scanning has little clinical relevance, and diagnosis must be suspected on more clinical grounds.

Other imaging studies

Additional imaging studies may be warranted, in patients with signs or symptoms that suggest visceral or bone involvement. Computed tomography (CT) scans of the chest, abdomen, pelvis; magnetic resonance imaging with contrast of the spine, and/or positron emission tomography (PET)/CT are helpful to identify lymphadenopathy, visceral masses, splenomegaly, effusions, or bone lesions.



Procedures used for the workup of Kaposi sarcoma include the following:

  • Punch biopsy : A punch biopsy of the skin or an endoscopic, pleural, or transbronchial biopsy is necessary to establish a definitive diagnosis. Typical histologic findings include proliferation of spindle cells, prominent slitlike vascular spaces, and extravasated red blood cells.
  • Bronchoscopy: Pulmonary involvement is typically characterized by a slightly raised (submucosal) cherry-red lesion. Biopsy is generally avoided due to the risk of bleeding.
  • Esophagogastroduodenoscopy (EGD) or colonoscopy: Gastrointestinal lesions are frequently observed. The yield of endoscopic biopsy may be low secondary to the submucosal location of many lesions.


Kaposi sarcoma does not lend itself to conventional tumor, node, metastases (TNM) classification. It should be individualized and customized for the type of Kaposi sarcoma. Patients with classic (sporadic) Kaposi sarcoma tend to have indolent disease and should not be subjected to extensive evaluation by imaging. A good physical examination, routine laboratories, and confirmatory biopsy may be all that is needed. If there is clinical suspicion for systemic disease, then appropriate imaging and even bronchoscopic or endoscopic procedures may be indicated.

Although no staging system has been accepted, several have been proposed. Some have included laboratory parameters as well as clinical features. One must remember that most patients with epidemic Kaposi sarcoma, the most common form of the disease in the United States, do not die of the disease. Therefore, factors other than tumor burden may have a role to play in survival. Because of this, the AIDS Clinical Trials Group (ACTG) has proposed a system based on immune status, extent of tumor involvement, and presence of systemic illnesses. The staging system has not been evaluated prospectively; however, some evidence suggests that it may have prognostic significance.

The ACTG Kaposi sarcoma staging classification has two categories: good risk and poor risk. [76, 40, 77] Criteria for good risk are as follows:

  • Tumor (T) - Confined to skin and/or lymph nodes and/or minimal non-nodular oral disease limited to the palate
  • Immune system (I) - CD4 greater than 150/mm 3
  • Systemic illness (S) - No history of opportunistic infection, thrush, unexplained fevers, more than 10% involuntary weight loss, or diarrhea persisting more than 2 weeks
  • Karnofsky performance status greater than 70

Criteria for poor risk are as follows:

  • Tumor (T) - Tumor-associated edema or ulceration, extensive oral Kaposi sarcoma, gastrointestinal Kaposi sarcoma, Kaposi sarcoma in other non-nodal viscera
  • Immune system (I) - CD4 less than 150/mm 3
  • Systemic illness (S) - History of opportunistic infection, thrush, unexplained fever, night sweats, more than 10% involuntary weight loss, or other HIV-related illness (eg, lymphoma, neurologic disease)
  • Karnofsky performance status less than 70
  • Other HIV-related illness (concurrent malignancy such as lymphoma or neurologic disease)

Good risk is shown with a 0 subscript and poor risk with a 1 subscript. For example, T0, S0, and I0 are good risk, and T1, S1, and I1 are poor risk. In the pre-HAART era, any category with poor risk designated the patient as an overall poor risk. One must remember that previous studies were conducted in the pre-HAART era. HAART has had a clear impact on survival by pushing many patients into the good risk category. Now it appears as though CD4 levels do not carry the same prognostic significance. Two broad categories have been defined, good risk (T0 S0, T1 S0, and T0 S1) and poor risk (T1 S1) in HAART responders. The original TIS classification may instead be more applicable to multidrug-resistant HIV.

Pre-HAART data confirm the use of the original TIS staging system. Analysis of 294 patients placed on ACTG clinical trials for Kaposi sarcoma from 1989 to 1995 confirmed that each of the variables of tumor, immune system, and systemic illness were independently associated with survival. [78] Immune system impairment is the single most important predictor of survival by multivariate analysis. Adverse prognostic factors for survival include prior or coexistent opportunistic infection (OI), the presence of B symptoms (weight loss, fever, and night sweats), and an absolute CD4 count of less than 300/μ L. The most important appears to be opportunistic infection (OI), with a survival of only 7 months versus 20 months without an OI. [79]

Challenges of the ACTG system include the following:

  • An accurate assessment of response to treatment for Kaposi sarcoma is often difficult because the lesions may not be amenable to conventional bidimensional tumor measurements.
  • Standard response evaluation criteria in solid tumors (RECIST) are not very useful for evaluating treatment effect in Kaposi sarcoma. New Kaposi sarcoma response criteria, using an assessment of the impact of treatment on tumor-related symptoms, are currently being evaluated prospectively.
  • ACTG response criteria establish a cutaneous lesion response as a 50% decrease in total body lesion count and a flattening of 50% of previously raised lesions. Evaluation of visceral and oral Kaposi sarcoma is more difficult because lesions in this type do not lend themselves to measurement by either imaging or physical assessment.