Computed tomographic metrizamide myelography in the evaluation of thoracic spinal osteoblastoma.

Osteoblastoma is an uncommon benign bone-form ing tumor originally described in 1932 by Jaffe and Mayer [1]. it presents c linically with unusually severe pain that mayor may not respond to mild analges ics such as aspi rin . The radiographic appearance of osteoblastoma is often considerably varied, but , in most cases, it is an expanding lytic bone lesion that is usually well circu mscribed even when it has attenuated and expanded the cortex [2 , 3]. Some degree of calcification may be present [2,3]. It is usually more than 1.5 cm in diameter. It has been described in almost all of the bones of the body, but the vertebral co lumn is the most common location of this tumor and it usually involves the appendages [2-5]. Its differenti al diagnostic possib ili ties include osteoid osteoma, aneurysmal bone cyst, osteosarcoma, and giant cell tumor. It bears a close similarity to osteoid osteoma clin ically, histologically [2, 4], and ul trastructurally [6]. Radiographic presentation is the most useful means of differentiating between these two entities [2, 4]. The purpose of this communication is to report on the findings and usefu lness of computed tomography (CT) metrizamide myelography in four patients with spinal osteoblastoma.