Atypical meningioma (WHO grade II) with osseous invasion

Case contributed by Dr Henry Knipe

Presentation

Left upper limb weakness and partial seizure.

Patient Data

Age: 70 years
Gender: Male

Large, enhancing right frontal extra-axial tumour with invasion through the right frontal bone into the scalp soft tissues. There is mass effect on the right frontal lobe, with a small amount of adjacent oedema, and partial effacement of the frontal horns. 

Large, enhancing right frontal extra-axial tumour with invasion through the right frontal bone into the scalp soft tissues. The mass has some cystic components. There is mass effect on the right frontal lobe, with a small amount of adjacent oedema, and partial effacement of the frontal horns. 

The patient proceeded to surgery. 

Histopathology

MICROSCOPIC DESCRIPTION: The sections show a meningioma with increased cellularity. The tumour forms solid sheets as well as scattered whorls. The tumour cells have enlarged and mildly pleomorphic nuclei with focal prominent nucleoli. There are up to 16 mitoses per 10 high power fields. Areas of necrosis are seen. Cerebral cortex is present and there is no evidence of brain invasion. The tumour invades through the dura into the skull bone. It involves the entire thickness of the bone through the cortex and it is 0.1mm from the outer periosteum. The tumour involves the circumferential radial bony margin. There is no evidence of malignant change. The features are those of atypical meningioma. The Ki-67 index is about 20%. About 10% of the tumour cells are weakly progesterone receptor positive.

DIAGNOSIS: Atypical meningioma with full thickness invasion into skull bone (WHO Grade II).

Case Discussion

Atypical meningiomas (WHO grade II) are more aggressive than WHO grade I meningiomas with a much higher recurrence rate (~40% vs ~12%). Imaging cannot reliably differentiate between the two.

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Case information

rID: 53654
Case created: 29th May 2017
Last edited: 29th May 2017
Inclusion in quiz mode: Included

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