Atypical meningioma (WHO grade II)

The patient went on to have a resection. 

Histology

MICROSCOPIC DESCRIPTION: The sections show a moderately cellular meningioma with focal infiltration into the attached dura. The tumour forms whorls and fascicles. No sheeting arrangement is seen. The tumour cells have enlarged nuclei and prominent nucleoli. There are up to 8 mitoses per 10 high power-power fields. Scattered small foci of necrosis are noted.

There is no brain parenchyma included. No malignant change is seen. The features are those of an atypical meningioma. The Ki-67 index is about 25%. Most of the tumour cells are progesterone receptor negative (about 5% positive).

FINAL DIAGNOSIS:

Atypical meningioma (WHO Grade II).

There is a large left frontal region extra-axial mass of variegated density and vivid slightly heterogeneous contrast enhancement measuring 6 x 4 x 5cm. The mass demonstrates some small hyperdense foci in its periphery that may represent calcifications, less likely subtle haemorrhage. The mass exerts positive mass effect upon the left cerebrum narrowing of the left interhemispheric fissure and with minor rightward subfalcine herniation.

There is 2.5 mm rightward midline shift. There is some mild oedematous changes within the white matter of the left frontal lobe. There is some inner table skull remodelling in the vicinity of the mass. No additional mass is identified.

Conclusion:

Large enhancing left frontal extra-axial durallydually based mass remodelling inner table, likelyalmost certainly a meningioma. Differential includes haemangiopericytoma.