False-positive Uptake on Positron Emission Tomography/Computed Tomography Immediately After Lung Biopsy: A Case Report

18F-fluorodeoxyglucose positron emission tomography (18F-FDG-PET) is an evolving tool in the field of oncology. 18F-fluorodeoxyglucose, however, is not a specific tool for malignant tumor that it may also accumulate in benign processes. To avoid false-positive interpretation of 18F-FDG-PET/computed tomography (CT), having knowledge of the potential pitfalls is important. The authors present a case of a patient with a lung mass who underwent fluoroscopy-guided transthoracic lung biopsy followed by 18F-FDG-PET/CT scan with a 4-hour interval between biopsy and scanning. Abnormally increased FDG uptake in the mass and pleural effusion was detected. Pathologic examination of the specimen, however, revealed only fibrous tissues with chronic inflammatory cells. On performing CT imaging, 1 month later, the mass and effusion had spontaneously resolved without treatment. Our findings suggest that PET/CT performed immediately following invasive procedures can result in false-positive results and thus mislead diagnosis. Therefore, the interval and order, in which PET/CT and invasive procedures are performed, should be carefully considered in oncologic work-up.