Left sided weakness.
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A right sided extra-axial mass arises from the inner surface of the skull vault, adjacent to the superior sagittal sinus which it invades and occludes. The mass is isointense to grey matter on both T1 and T2 with vivid contrast enhancement. It is also isointense on DWI. Unfortunately ADC is not available. No particularly prominent flow voids. It is surrounded by vasogenic edema. The overlying bone is abnormal with loss of the normal fatty marrow and tumor can be extending beyond the outer table.
The patient went on to have a craniotomy and excision of the mass.
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:
- parenchymal invasion
- chordoid histological sybtype