Osteoid Osteoma

  • Etiology: benign tumor containing osteoid in a stroma of loose vascular connective tissue
  • Radiograph: < 2 cm in size, femur / tibia / humerus most common, usually in cortex, central calcification, small radiolucent nidus with reactive sclerosis, periosteal new bone, if in spine posterior elements has sclerotic pedicle on ipsilateral side and scoliosis convex away from side of tumor
  • Bone scan: increased uptake, useful for intraoperative localization
  • CT: small lucent nidus that may contain calcification surrounded by sclerosis
  • MRI: radiolucent nidus (T2 hyperintense), surrounding sclerosis (T2 hypointense)
  • Clinical: age range 6 – 17 years old, pain relieved by NSAIDs, in spine causes painful scoliosis

Cases of Osteoid Osteoma

Radiograph and CT of osteoid osteoma of the spine
AP radiograph of the thoracic spine shows an indistinct margin of the left T10 pedicle and mild scoliosis convex right. Axial CT without contrast of the T10 vertebral body with coronal and sagittal 2-D reconstructions shows a small round lucent nidus with central calcification in the left T10 pedicle surrounded by sclerosis.
Radiograph and CT of osteoid osteoma of the femur
AP radiograph of the pelvis shows a round lucent lesion in the right femoral neck. Coronal 2D reconstruction and axial CT without contrast of the pelvis shows the lesion to be centered in the cortex, to have a central calcification in a radiolucent nidus, and to be surrounded by reactive sclerosis. There is also a left hip effusion on the lower left CT image.