A 59-year-old female patient with a 2-year history of lung cancer complained of pain throughout her whole body, especially in the left forearm, that had lasted 1 month. No evidence of fever or trauma was found, and no significant abnormalities were observed in laboratory examinations that investigated the tumor marker, serum alkaline phosphatase, calcium, and parathyroid hormone levels. She was referred for an evaluation of metastatic disease through a whole-body bone scan using 99mTc-methylene diphosphonate (MDP), which revealed a marked striped tracer accumulation in the left distal forearm (Fig. 1). Single photon emission computed tomography/computed tomography (CT) hybrid imaging of the left forearm was performed and only revealed cortical thickness in the radius on CT corresponding to the high tracer uptake region (Fig. 2A and 2B). The C-terminal cross-linking telopeptide of type I collagen value was 1.04 ng/mL (normal range, 0.12 to 0.75). Using the radiologic, biochemical, and biopsy (Fig. 2C) findings a final diagnosis of Paget disease (PD) was established.