False-positive 18-fluorodeoxyglucose positron emission tomography-computed tomography (FDG PET/CT) scans mimicking malignancies.

AIM 18-Fluorodeoxyglucose (FDG) positron emission tomography-computed tomography (PET/CT) is an imaging modality that is often used to help differentiate benign from malignant pulmonary lesions and it has been shown to be more efficacious than conventional chest computed tomography (CT). However, some benign lesions may also show increased metabolic activity which can lead to false-positive PET findings. We aim to illustrate false positive findings of PET scan that simulate lung cancer in a variety of diseases. METHODS Patients referred to Yedikule Chest Diseases and Surgery Teaching and Research Hospital with increased FDG uptake for which histological results were available over a 2-year period (2013-2014) were reviewed. Seven patients with false-positive PET/CT findings were reported in this study. RESULTS The majority of lesions showing increased metabolic activity were due to malignant diseases. However, increased 18 F-FDG uptake was also seen in benign lesions such as active pulmonary inflammation or infection, granulomatous processes and fibrotic lesions. CONCLUSION The integration of clinical history, morphologic findings of lesions on the CT component, and metabolic activities of PET/CT scan can help reduce false interpretations. Interventional procedures may be needed for tissue confirmation for differential diagnosis.