A clinicopathologic correlation in osteoblastoma of the spine in a child.

Spinal osteoblastomas are considered benign tumors but can be locally aggressive. Patients usually present with pain and undergo radiologic and histologic work-up to establish a diagnosis. Osteoblastomas have discordant appearances on CT scans and MRI because of the inflammatory response seen on MRI that characterizes these tumors - the "flare" phenomenon. Solely using MRI can lead to over-resection, as signal abnormality may include areas devoid of tumor. There are a few reports of this phenomenon in the radiology literature, but to our knowledge, there are none in neurosurgery journals. We report an 11-year-old boy who presented with back pain and radiculopathy with an osteoblastoma at the L4 level. We totally excised the lesion to definitively treat the patient but also, based on MRI findings, differentially biopsied portions of the lesion and correlated them to the imaging studies, to confirm that the intense reactive portion of the lesion was devoid of tumor cells.