Vertebral osteoid osteoma associated with paravertebral soft-tissue changes on magnetic resonance imaging. Report of two cases.

Soft-tissue changes associated with osteoid osteoma have been described in the digits of the hands and feet as well as the long bones. Only six cases in which such changes occurred in the spine have been reported. Magnetic resonance (MR) imaging facilitates the determination of such changes. Establishing a diagnosis, however, is especially difficult in spinal osteoid osteoma when using MR imaging. Therefore, osteoid osteoma-related soft-tissue changes demonstrated on MR imaging raise the question of malignancy and may lead to unnecessary long-term treatment or biopsy sampling. The authors report two cases of spinal osteoid osteoma in which paravertebral soft-tissue changes were observed on MR imaging to mimic malignant soft-tissue tumors.