MICROSCOPIC DESCRIPTION: The sections show a moderately cellular meningioma with infiltration into the attached dura. The tumour forms scattered whorls. The background contains abundant mucoid material, in which embedded cords of tumour cells are seen, imparting a chordoid-like appearance. The chordoid pattern occupies more than 50% of the total area. Microcystic change is also focally seen. The tumour cells have ovoid nuclei with no nuclear pleomorphism. Mitoses are inconspicuous. The tumour cells are progesterone receptor positive. The Ki-67 index is about 2% (not shown).
There is no necrosis. No brain parenchyma is seen. In one specimen tumour invades into, but not through, the cortical bone. There is no malignant change.
Chordoid meningioma with bone invasion (WHO Grade II).