Osteoblastoma

Abstract

Osteoblastoma is a benign osteoid and bone-forming tumor with numerous osteoblasts lining immature bone trabeculae and scattered multinucleated giant cells of osteoclastic type and a loose fibrovascular stroma. It lacks peripheral bone sclerosis. Diameter is greater than 2 cm. The incidence is greater in males than in females (2:1). The first two decades of life account for more than 70 % of cases. Sites of involvement: One-third in spine, where in vertebrae, osteoblastoma tends to involve the posterior elements, and one-third in tubular bones with predilection for proximal and distal femur and proximal tibia and proximal humerus. The radiographic appearance is quite variable and often nonspecific. The lesion is oval and expansile but usually well defined. It may be radiolucent, radiodense, or mixed. Histologically, the lesion is similar to the “nidus” of osteoid osteoma. Osteoblastoma is usually very well circumscribed. The lesion is composed by anastomosing immature osteoid and bone trabeculae embedded in a loose fibrovascular stroma. Treatment is wide excision or en bloc resection of the lesion.