Aggressive osteoblastoma of the temporal bone: an unusual cause of facial palsy.

Osteoblastoma was first described in 1956 by Lichenstein and Jaffe. It represents 0.8--1% of all bone tumors and affects young adults, with male preponderance. It predominantly affects the axial skeleton and vertebrae with only 14--20% of tumors affecting the skull. The most commonly affected sites are maxilla, temporal, sphenoid, occipital, ethmoid and frontal bones. Histologically it is a benign, vascular, osteoblastic tumor with variable osteoid mineralization and absent mitotic activity or atypia. It can however manifest aggressive behavior, invading the surrounding tissues.