Osteoid osteoma: the difficult diagnosis.

The diagnosis of osteoid osteoma can be difficult. We present eight children where the diagnosis of osteoid osteoma was difficult, due to a clinical history suggesting an alternative diagnosis, misleading radiological findings, or where the osteoid osteoma was in an unusual site. In some cases, diagnosis was only reached after biopsy, despite radiological investigation and radioisotope studies. The diagnosis should be considered in a child with bony pain or bony swelling, especially where the history is a chronic one. We present a radiological algorithm for the investigation of patients suspected of having an osteoid osteoma.