The patient went on to have a craniotomy and excision of the mass. 

Histology

MICROSCOPIC DESCRIPTION: The sections show a moderately cellular meningioma with infiltration into the attached dura. The tumor forms whorls in some parts. In others, it has a chordoid-like appearance, in which cords of tumor are seen in myxomatous stroma. The chordoid-like areas occupy about 50% of the tumor. The tumor cells have ovoid nuclei with no nuclear pleomorphism. Mitoses are inconspicuous. There is no necrosis. Several tumor
nests invade into the cerebral cortex. There is no malignant change.

The tumor cells are EMA positive and they are CAM5.2 negative. The Ki-67 index is up to about 10%. About 30% of the tumor cells are progesterone receptor positive with 2+ intensity.

DIAGNOSIS: Chordoid meningioma (WHO Grade II). 

Note that this tumor is designated WHO grade 2 on two grounds:

1. parenchymal invasion
2. chordoid histological sybtype