Treatment of osteoid osteoma in the vertebral body of the lumbar spine by radiofrequency ablation.

Osteoid osteoma is a rare bone tumor initially described by Jaffe in 1935. It is characterized as a bone-producing tumor that is most frequently observed in the lower extremities of children or young adults (11-22 years). Osteoid osteoma is differentiated from osteoblastoma according to size. Osteoid osteoma is smaller than 1.5 centimeters in diameter. In approximately 10% to 25% of the cases, the tumor is observed in the vertebral column with a predilection for posterior elements of the vertebrae. In only 10% of the cases in which the spine is affected is it found in the vertebral body, but involvement of the spine is more common in the lumbar vertebrae. Here the disease is characterized by localized pain in the affected vertebra, and possibly by radiating pain similar to a disc hernia, although without other findings in the physical and neurological evaluation. The pain is generally worse during the night and improves with the use of non-hormonal anti-inflammatory drugs. Scoliosis secondary to pain and muscular spasms is a common finding in affected adolescents (63% to 70%). If treatment is delayed, scoliosis may become a complication since the curve may become structured through asymmetric inhibition of the growth of the vertebral epiphysis. The tumor is generally located at the apex of the deformity. When the fourth or fifth lumbar vertebra is involved, it is generally associated with pelvic obliquity. The tumor niche, even when small, can generally be observed by means of scintigraphy with technetium. It is possible to identify the lesion on tomographic sections of thickness less than 1.5 centimeters and magnetic resonance images (MRI). Osteoid osteoma is better seen on MRI because of its high signal in the bone around the lesion in sections with T2 weighting, thus demonstrating local edema.