Unexpected Detection of Abscessualized Lung Carcinoma on Tc-99m-HMPAO-labeled Leukocytes Scintigraphy Misdiagnosed on Chest Computed Tomography.

Technetium-99m (Tc-99m)-hexamethylpropylene amine oxime (HMPAO)-labeled leukocytes scintigraphy is well established for investigating and diagnosing infections in bone and soft tissue, as well as for the detection of occult infection. A 71-year-old female who was recently diagnosed with bronchopulmonary neuroendocrine tumor of the right lung was referred for an intermittent fever of unknown origin associated with chill at night for the last month. Chest computed tomography (CT) scan showed a thrombotic widespread of the superior vena cava and a solid pathological tissue in the superior segment of the inferior lobe of the right lung with consensual atelectasis. Being a carrier of port-a-cath, an infection of this device was suspected. Therefore, Tc-99m-HMPAO-labeled leukocytes single-photon emission computed tomography (SPECT) was performed, and matching pairs of CT scan and Tc-99m-HMPAO-labeled white blood cell SPECT images were fused. Through this means, it was found that the area of the radiotracer increased uptake corresponded with the soft tissue density mass detected by CT scan localized at the inferior lobe of the right lung. The hybrid SPECT/CT fused imaging was crucial for diagnosis of the presence of a lung abscess localized in correspondence with the known lung cancer region.