Positron emission tomography (PET) with fluorine-18-2-fluorodeoxyglucose (F-18 FDG) is a noninvasive diagnostic modality in various cancers. Unexpectedly increased physiologic muscle uptake may be encountered on F-18 FDG PET scans. A 46-year-old male farmer (right-handed user) with papillary thyroid cancer underwent F-18 FDG PET/CT scan for evaluation and following treatment planning. The PET/CT images unexpectedly showed asymmetrically increased uptake in right pectoralis major, right subscapular muscle, and right triceps brachii. These appearances of the imaging characteristics led to a manifestation of right chest and right upper arm result from heavy workload from his job.