The most likely diagnosis is that of an atypical meningioma, although a hemangiopericytoma or dural metastasis should also be considered.

The patient went on to have a craniotomy and excision.

Histology

Sections show meningioma, focally associated with thin rims of fibrous tissue and neutrophil. The pattern is predominantly meningothelial. Focal infiltration by meningioma into brain tissue is identified. Mitotic activity is not elevated.

Final diagnosis: atypical meningioma (WHO grade II).

Comment: This meningioma was designated as being atypical because of the focal infiltration into brain tissue, which is now sufficient to denote WHO grade II even with all other histological features consistent with a lower grade.