Imaging studies in 17-year-old girl who complained of left thigh pain for several months. Anteroposterior (A) and lateral (B) radiographs of left hip show small radiolucent lesion with thick sclerotic rim of reactive bone, suggestive of osteoid osteoma. C, Computed tomography clearly shows nidus and confirms diagnosis. D, Radiofrequency ablation probe placed into nidus under CT guidance.