Osteoid osteoma of the acetabulum: diagnosis and medical treatment.

We describe the medical management of an acetabular osteoid osteoma in an 11-year-old girl. There was a 2-year delay until proper diagnosis of the patient's pathology was made. Accurate localization of the nidus in the subchondral bone, involving the cartilage, is difficult on the basis of plain radiographs.