What is the role of nuclear imaging in the workup of Kaposi sarcoma (KS)?

Updated: Apr 11, 2019
  • Author: Jessica Katz, MD, PhD, FACP; Chief Editor: Edwin Choy, MD, PhD  more...
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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%. [73] Presently, this type of scanning has little clinical relevance, and diagnosis must be suspected on more clinical grounds.

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