Feline intracranial meningioma with skull erosion and tumour extension into an area of skull hyperostosis.

Skull hyperostosis is a frequently recognised feature of meningioma in feline and human patients, occurring at a frequency of around 4.5% of human cases. Evidence of osteolysis with extension of meningioma into, and in some cases through, the region of skull hyperostosis is much less commonly described in human patients. Here we present a 12-year-old cat with marked skull hyperostosis secondary to an intracranial meningioma, with magnetic resonance imaging and computed tomography evidence of tumour extension into the skull, centrally within the region of hyperostosis. Only a thin layer of bone was remaining between the mass and the extracranial region. Surgical resection of the region of skull demonstrating tumour invasion and the underlying mass resulted in good resolution of clinical signs and no post-surgical recurrence of meningioma within the 5 months follow-up period. Histopathological examination confirmed the mass to be fibroblastic meningioma.