99mTc-MIBI imaging of cutaneous AIDS-associated Kaposi's sarcoma

Kapoksi's sarcoma (KS) is a common neoplasm complicating acquired immunodeficiency syndrome (AIDS). Skin, mucus membranes, lymph nodes, gastrointestinal tract and lungs may be involved. Kaposi's sarcoma has been demonstrated by scintigraphy, and a (99m)Tc-hexakis-2-methoxy isobutyl isonitrile (MIBI) scan can demonstrate lymphoma and tumors of the brain, nasopharynx, thyroid, parathyroid, lung, breast and kidney. It may also be useful for detecting and delineating the extent of KS. The objective of this study was to determine the efficacy of (99m)Tc-MIBI scanning to demonstrate cutaneous AIDS-associated KS, lymphedema and lymphadenopathy in the extremities.

Whole body (99m)Tc-MIBI scans were obtained on 40 patients with AIDS-associated KS. Abnormal uptake of (99m)Tc-MIBI in the skin, subcutaneous soft tissues and lymph nodes was compared with the clinical assessment.

The (99m)Tc-MIBI uptake was noted in the cutaneous/subcutaneous KS of the extremities with a sensitivity of 73.53%, a specificity of 96.91% and an accuracy of 91.31%. Abnormal lymph nodes and lymphedema were detected in more patients on (99m)Tc-MIBI scans (33 and 18 patients) than clinical assessment (10 and 12 patients), respectively. Lymphedema of the lower extremity was found in four of 17 patients without any palpable or abnormal lymph node uptake of (99m)Tc-MIBI in the inguinal regions. Follow-up (99m)Tc-MIBI scans after treatment showed no uptake in the skin lesions and decreased uptake in the lymph nodes corresponding to complete clearing on clinical assessment.

(99m)Tc-MIBI imaging provides additional information on the extent of lymph node involvement and more precise staging and therapeutic planning. It may be useful as a predictive test or follow up of response of cutaneous KS to treatment.