Indium-111 labeled leukocyte uptake: false-positive results in noninfected pseudoaneurysms

Indium-111 (In-111) leukocyte scintigraphy was performed in two patients with postsurgical pseudoaneurysms as part of preoperative evaluation for evidence of graft infection. Despite positive In-111 uptake by the pseudoaneurysms, surgical and pathologic examinations failed to reveal any evidence of infection. The most likely explanation for the false-positive results is the labeling of "contaminating" platelets and erythrocytes in the leukocyte mixture. Caution must be exercised in interpretation of In-111 leukocyte scans in patients with postsurgical pseudoaneurysms.