Atypical meningioma

Case contributed by A.Prof Frank Gaillard

Presentation

Headache.

Patient Data

Age: 45-year-old

MRI Brain

Modality: MRI

A heterogeneously enhancing extra-axial solid mass with a large cystic component is noted on the left. Underlying sulci and gray matter are distorted. Some underlying vasogenic oedema significant mass effect are present. 

The solid component demonstrates some restricted diffusion (similar ADC to parenchyma). Punctate susceptibility on the gradient echo sequences with no identifiable calcification on the CT  (not shown) likely represents hemosiderin. 

Conclusion: The imaging characteristics are somewhat atypical, while the large cystic component and the lack of significant contrast enhancement on CT is atypical for meningiomas, however the extraaxial location, diffusion restriction and the overall high prevalence of meningiomas suggests that meningioma is most likely, particularly an atypical or malignant meningioma. Other differentials include meningosarcoma or haemangiopericytoma. 

The patient went on to have surgery.

Histology

MACROSCOPIC DESCRIPTION:  A sheet of roughly triangular cream tissue consistent with dura, 65x50mm in cross section. One of the surfaces is smooth. The opposite surface is focally ragged and few small cream papillary outgrowths are seen. 

MICROSCOPIC DESCRIPTION: The sections show a moderately cellular tumour with infiltration into the attached dura. It comprises whorls and fascicles. In some areas, there is a loss of whorls with sheeting arrangement. Microcystic change is present in the background. The tumour cells have ovoid nuclei and prominent nucleoli. There is no small cell change. Up to 5 mitoses per 10 high power fields are seen. There are occasional foci of necrosis. No brain parenchyma is included in the biopsy. The dura is chronic inflamed. The features are those of atypical meningioma. There is no evidence of malignant change. Less than 5% of the tumour is progesterone receptor positive. The Ki-67 index is about 8%.

FINAL DIAGNOSIS: Atypical meningioma (WHO Grade II).

MRI Bain (selected images) - 8 years later

Modality: MRI

Selected multiplanar images demonstrate multiple extra-axial solid enhancing tumours scattered along the left cerebral hemisphere: left anterior frontal, left posterior frontal parafalcine, left frontoparietal region at the vertex, and left posterior temporal region. These have been increasing in size over the last years. 

Modality: Pathology

The patient underwent a new resection due to the recurrent tumour.

MICROSCOPIC FINDINGS: The sections show a meningioma with attached dura. There is mild increase in cellularity. The tumour forms sheets. Whorls are inconspicuous. The tumour cells have focal mildly enlarged nuclei with conspicuous nucleoli. There are up to 5 mitoses per 10 high power fields. No necrosis is seen. No brain parenchyma is present. There is no evidence of malignant change. The dural edges appear clear of tumour. The features are those of atypical meningioma. The Ki-67 index is about 10%. About 5% of the tumour cells are progesterone receptor positive.

DIAGNOSIS: Left parietal lesion: Atypical meningioma (WHO Grade II).

Case Discussion

Atypical meningioma (WHO Grade II) is a more aggressive subtype of meningioma that has significantly higher five-year recurrence rate (41%) compared to that seen in grade I (benign) meningiomas (12%).

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Case Information

rID: 48775
Case created: 23rd Oct 2016
Last edited: 1st Nov 2016
Inclusion in quiz mode: Included

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