FIG. I FIG. 2 808 THE JOURNAL OF BONE AND JOINT SURGERY Benign Osteoblastoma of the Atlas

We recently encountered a patient with benign osteoblastoma ofthe atlas. The roent-genographic and microscopic features ultimately were characteristic 1,2.3,5.7, but the loca-tion ofthe lesion was unusual. Case Report J. B.,an eleven-year-old white boy, first noted pain and stiffness in the back of his neck in December 1968. He denied any episode of trauma to the neck. An examination at that time revealed moderate paracervical ten-derness and spasm with no tenderness of the spinous processes. Cervical spine roentgenograms were interpreted as normal and the patient was treated with aspirin. heat, and gentle message. His condition improved over the next few months, but in May 1969 he began to have aching pain in the occiput and high cervical spine. He had neck stiffness in the morning which improved during the day. but reappeared at night. This persisted throughout the summer and he could neither swim nor dive because ofthe pain in his neck. New roentgenograms were made in August 1969. While the anteroposterior roentgenogram did not demonstrate a lesion, the lateral view showed an expansile mass of the posterior arch of the first cervical vertebra with a mildly sclerotic rim (Fig. 1). Tomo-grams showed the slightly expansile, irregularly lucent lesion ofthe first cervical vertebra. A careful neurological examination at this time was entirely normal. A skeletal survey and appropriate laboratory work were withi