Diagnosis of Spinal Osteoid Osteoma

Even though several hundred cases of extra-axial osteoid osteoma have been recorded, there are reports of only approximately 50 cases of this lesion in the spine (14), and few of these have appeared in the radiological literature (3, 4, 11). The cases in this communication illustrate the diagnostic challenge and clinical importance of this benign lesion when it occurs in the spine. Due to the many excellent articles on the subject (10), a description of the pathology will not be included in this discussion. Case I: This unfortunate boy was first investigated at nine and one-half years of age for a limp and increasing right flank and thigh pain. No significant abnormality was found. When he was admitted to Children's Hospital Medical Center, he had the features of Cushing's syndrome due to three injections of a long-acting corticosteroid preparation. He walked with an erratic, jerky gait and had a most peculiar posture (Fig. 1). Plain roentgenograms of the spine (Fig. 2) showed marked osteoporosis and multiple, small, vertebral end-plate infractions, but no structural cause was found for the scoliosis. A myelogram was normal. Without a definitive diagnosis, the boy was managed on aspirin and a back brace to correct the scoliosis. During the next three years the deformity and pain gradually decreased. At the end of this time, plain roentgenograms of the lumbar spine (Fig. 3) showed that his bones were normally mineralized, but for the first time the radiological diagnosis of osteoid osteoma of the right side of the neural arch of L4 was made. The right lamina and inferior articular process of L4 were expanded and dense, and a small central nidus was surrounded by a sclerotic margin (Fig. 3, A). As he was improving spontaneously, it was decided to continue conservative management. He was last seen seven years after the onset of his symptoms. At this time he had a normal gait and posture and was able to control occasional back pain with small doses of aspirin. A roentgenogram (Fig. 4) showed complete bony fusion between the right side of the vertebral arches of the fourth and fifth lumbar vertebrae. The nidus was no longer visible. On a review of the original spinal roentgenogram (Fig. 2), there can be no doubt that the lesion was present at that time; in fact, the sclerosis of the right inferior articular process of L4 was highlighted by the steroid-induced osteoporosis of the other bones. Case II: This 13-year-old girl gave a 4-month history of left lower back pain which caused difficulty in moving and walking. She had to stop participating in sports and was finally hospitalized because of the pain. On examination there was local tenderness in the lumbar area, limitation of movement, and mild right scoliosis with its apex in the lumbar region. No motor or sensory changes could be demonstrated, and the reflexes were normal. All special examinations including plain roentgenograms and a myelogram were considered normal.