Osteoblastoma of the lumbar spine as a cause of chronic low back pain.

We report a case of osteoblastoma in the uncommon location of the L5 lumbar vertebra, detailing the clinical and radiologic aspects. Although the plain radiographs of the patient were normal, computed tomographic scans of the lumbar region confirmed the diagnosis of osteoblastoma or osteoid osteoma of the L5 vertebra. The patient was referred to the orthopedic department for operation. Histologic examination revealed osteoblastoma of the L5 vertebra. Following surgery, the patient's pain resolved completely. Although osteoblastoma is extremely rare in the spine, it should be included in the differential diagnosis as a cause of chronic back pain, especially in young males with painful scoliosis and/or radicular-type leg pain. The tumor is often not readily apparent on plain radiographs. Therefore, advanced radiological investigation is necessary to establish the correct diagnosis.