We present a 73-year-old man with a new diagnosis of right upper lung adenocarcinoma. Right elbow x-ray and Tc-99m MDP whole body bone scan were performed due to a reddish, swollen, and painful right forearm for 1 week. X-ray, performed on March 25, 2008, showed an osteolytic lesion in the proximal right radius with surrounding soft tissue swelling. Tc-99m whole body bone scan, performed on March 19, 2008, had shown a single area of intense tracer uptake in the proximal right radius and no other bony lesion was identified. Infectious processes were considered initially, but the clinical symptoms and signs didn't improve after antibiotic treatment for 10 days. Incisional biopsy of the proximal right forearm was performed for diagnosis. Histopathologic examination confirmed a bone metastasis in the proximal right radius.