Misinterpretation of FDG-avid Pelvic Lymph Node Lesions as Distant Metastasis in a Patient with Recurrent Lung Cancer

F-18 FDG PET/CT is a sensitive imaging modality for evaluating the recurrence of nonsmall-cell lung carcinoma (NSCLC), and also for detecting the inflammatory and infectious processes which can frequently cause false positive results when attempting to evaluate the tumor status. Here, we present a case of recurrent NSCLC at the chest wall identified by F-18 FDG PETICT imaging. Increased FDG uptake foci at the right pelvic lymph nodes were also found. Local recurrence of cancer with distant metastases at the pelvic nodes was highly suspected, but the pelvic lymph nodes signal was proven to be a false positive result caused by tuberculosis (TB) after surgical dissection. Iliac lymphadenopathy is an unusual presentation of TB reactivation, and no previous reports have suggested that it may cause false positive F-18 FDG PET findings in cancer patients. The possibility and the various presentations of opportunistic infections, such as TB, should be carefully considered in patients with malignancies. In addition, the study of the common pattern of failure in NSCLC recurrence may be helpful to prevent the misinterpretation of FDG-avid inflammatory lesions as distant metastases.