False-positive findings on F-18 fluoro-2-deoxy-D-glucose positron emission tomography in a patient with nasopharyngeal carcinoma and extensive sinusitis

F-18 fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET) scanning has been used to evaluate nasopharyngeal carcinoma (NPC). However, with positive FDG uptake in the contiguous paranasal sinus, it may be difficult to differentiate tumor invasion from an inflammatory process. We describe such a patient with NPC in whom an FDG PET scan revealed intense FDG uptake in and above the nasopharynx, suggesting tumor invasion in the sphenoethmoid sinuses. After fusion PET/CT imaging, sphenoethmoid sinusitis rather than tumor invasion was noted. This patient achieved complete remission after current chemoradiotherapy.