18F-FDG PET/CT plays an important role in the management of non-small-cell lung cancers (NSCLC). The treatment options for NSCLC depend upon the initial staging of the disease. The authors report a case with a potential pitfall of overlooking a site of FDG uptake as radiopharmaceutical extravasation at an injection site. The PET/CT demonstrated a T2a N2 bronchial carcinoma, with a solitary focus of FDG uptake at the left antecubital fossa where FDG was administered. Careful interpretation of the images reveals a solitary skeletal metastasis in the left proximal ulna, which makes the disease stage IV rather than IIIA, leading to a significant difference in treatment.