Giant intraosseous meningioma mimicking fibrous dysplasia

We illustrate a case of a giant primary intraosseous meningiomas (PIMs) with optic nerve compression treated by partial resection. A 48-year-old female presented with visual disturbances exophthalmus, diplopia and eye pain due to optic nerve compression. The patient had a past history of fibrous dysplasia treated surgically with partial resection by ENT in 2010. Histology confirmed the diagnosis. Two years later she presented with further decrease in visual acuity and diffuse hyperostosis. In this context she underwent a neurosurgical procedure consisting in craniotomy and further partial resection of the lesion including optic canal decompression. The second pathological examination demonstrated an extensive meningioma (WHO grade I) of the skull base. We recommend that in cases of diffuse hyperostosis the differential diagnosis include diffuse intraosseous meningioma. If complete surgical resection is not achievable, a biopsy to confirm the diagnosis is recommended. Treatment options include complete or partial resection followed by adjuvant radiotherapy.