- Etiology: benign tumor containing osteoid in a stroma of loose vascular connective tissue
- Bone scan: increased uptake, useful for intraoperative localization
- Extra-articular:
— 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 have sclerotic pedicle on ipsilateral side and scoliosis convex away from side of tumor
— CT: lucent nidus surrounded by focal cortical thickening
— MRI: T2FS shows hyperintense edema surrounding nidus and hypointense surrounding sclerosis, T1 post contrast shows cortical thickening and enhancing nidus - Intra-articular (hip):
— Radiograph: normal (no periosteal reaction or cortical thickening)
— CT: tiny radiolucent nidus which may be nearly inconspicuous and which may have central calcification
— MRI: T2FS shows geographic marrow edema and joint effusion with synovitis - Clinical: age range 6 – 17 years old, pain relieved by NSAIDs, in spine causes painful scoliosis
Radiology Cases of Osteoid Osteoma



