Aggressive osteoblastoma with degeneration to secondary aneurysmal bone cyst

Abstract

ABSTRACT A 4-year-old male patient presented with headaches that started 18 months ago and were associated with progressive loss of balance and difficulty walking. Magnetic resonance imaging (MRI) demonstrated an expansile extra-axial mass lesion in the posterior aspect of the posterior fossa on the left, compressing the adjacent brain, as well as the cerebellar hemispheres; it also distorts the fourth ventricle with severe obstructive hydrocephalus upstream. Histological evaluation diagnosed aggressive osteoblastoma with a secondary aneurysmal bone cyst of the skull. We report a case of aggressive osteoblastoma in which the lesion in the MRI was mimicking brain tumor or intracranial primary tumor rather than primary bone tumor.