Benign osteoblastoma accounts for approximately 1% of all primary bone tumors and 3% of all benign bone tumors. The exact relationship between this lesion and osteoid osteoma is unclear. Osteoblastomas are characteristically larger in size than osteiod osteomas with usual diameter measuring greater than 1.5 cm. This lesion most commonly occurs in individuals in the second or third decade of life. Males are more commonly affected . Muscle spasm, scoliosis, and neurologic manifestations sometimes accompany spinal lesions, which tend to involve the posterior elements of the spine. Although they may affect any bone, they are commonly found in the thoracic and lumbar vertebral bodies as well long tubular bones of the lower extremities. The long tubular bones of the upper extremity are less common sites of involvement. Plain radiographic findings of a geographic, expansile, partially calcified lesion suggest the diagnosis of osteoblastoma. Associated soft tissue mass, bone expansion and cortical thinning would suggest aggressive (malignant)osteoblastoma. Plain-film radiographs are usually sufficient to demonstrate the lesion and suggest the diagnosis. CT may aid in differential diagnosis located in complex anatomic regions such as the vertebrae. MRI may be helpful to evaluate lesions that extend into the soft tissues. Depending on the location of the lesion, differential diagnosis includes aneurysmal bone cyst, eosinophilic granuloma, enchondroma, fibrous dysplasia,chondromyxoid fibroma, or solitary bone cyst. Differential diagnosis for agressive osteoblastoma includes osteosarcoma.