This article reports a case of osteoid osteoma of the proximal humerus. A 22-year-old man had pain in the right shoulder for 18 months after a traffic accident. We found a small sclerotic change in the proximal humerus on X-ray images and typical nidus on CT in his first visit to our hospital. The tumor was removed and the pain in the shoulder disappeared completely after operation. He underwent arthroscopic surgery for the pain at another hospital one year ago, but the cause of the pain was not identified. We reviewed X-ray images which were taken 18 months ago at that hospital. The images did not show any marked changes. Osteoid osteoma of the proximal humerus is rare but we should consider the diagnosis of osteoid osteoma for patients with severe and long-term pain in the shoulder.
