Unusual manifestation of vertebral osteoid osteoma: case report.

We report the case of a 64 year-old man with a clinical history suggesting a low thoracic-cord involvement, in which an unexpected vertebral osteoid osteoma was discovered. The patient underwent MRI of the thoraco-lumbar spine, which included sagittal and axial T1-weighted images, and sagittal double-echo T2-weighted images. Subsequently, CT scan was carried out with 2-mm-thick axial sections, aimed at T10 vertebra. Magnetic resonance imaging disclosed an extra-axial mass at T10 level. Computed tomography scan suggested an osteoid osteoma of the tenth thoracic vertebra, involving the lamina with marked sclerosis and prevalently endocanalar extension. Histology following surgical resection confirmed the diagnosis. In the reported case CT scan provided the correct pre-operative diagnosis of osteoid osteoma despite its unusual clinical--anamnestic presentation. Magnetic resonance imaging was useful in establishing the relationship of the neoplasm with the spinal cord.