Osteoid osteoma is a benign osseous tumor. They usually present in adolescents but can be seen in older patients and younger children as in this case. They are classically associated with significant night pain that is relieved by NSAIDs.
The appearance on radiographs and CT consists of a lucent nidus surrounded by reative sclerosis. Central mineralization may be seen within the nidus. If the nidus measures over 2cm in length the lesion should be termed osteoblastoma.