Osteoblastoma of the spine with discordant magnetic resonance imaging and computed tomography imaging features in a child.

STUDY DESIGN: Case report. OBJECTIVE: To describe the magnetic resonance imaging (MRI) and computed tomography (CT) findings of spinal osteoblastoma and illustrate how MRI features can be potentially misleading. SUMMARY OF BACKGROUND DATA: Osteoblastoma is a rare benign tumor of bone that is known to incite a localized inflammatory response. These inflammatory features can simulate malignant behavior on MRI and can lead to misdiagnosis and unnecessarily aggressive resection unless one recognizes the classic benign features on CT. We present a case of osteoblastoma in a child to illustrate this concept. METHODS: The patient's clinical and radiologic history is discussed with a brief review of the relevant literature. RESULTS: A 9-year-old girl with back pain receives an MRI of the lumbar spine demonstrating a sacral tumor with potentially malignant features including extensive marrow edema and enhancement. A CT demonstrates a well-circumscribed lesion without lytic changes or malignant bone formation. A benign lesion was favored given the CT features and conservative resection was performed. Final pathologic diagnosis was osteoblastoma. CONCLUSION: This case illustrates that the MRI findings for osteoblastoma can be misleading and caution should be used when evaluating benign tumors with known inflammatory responses on MRI. CT features seem to more accurately reflect the true nature and extent of the tumor.