LAUSR

Osteoblastoma is a rare nonfibroblastic osteoid tissue forming primary bony tumor usually arising in the medullary cavity /diploic space of any bone. Calvarium is an extremely rare site of its origin. Clinically, two types of Osteoblastomas are noted: benign/conventional/typical and aggressive/high grade. Their imaging features are non-differentiating and nonspecific, histopathological features have afew subtle but nonspecific differences, and they have highly distinct clinical behavior. We hereby report an extremely rare case of a large aggressive cranial Osteoblastoma, which developed massive inoperable multifocal recurrence 15 months after total en-bloc resection with wide margins. A concise review of cases of aggressive Osteoblastomas involving cranium available in English Literature is also presented as an update.