Meningioma - Tumours of the nervous system

Meningioma

Definition

Slow growing tumour arising from the meningeal covering of the brain and spinal cord.

Incidence

They account for ∼20% of all intracranial tumours.

Age

Peak age 40–70 years.

Sex

F > M (2.5:1)

Pathophysiology

Meningiomas may grow to a large size over a period of years. Most are benign, with 10% behaving in a malignant fashion. If they arise close to the skull they may erode the bone. Meningiomas often occur along venous sinuses.

Clinical features

Most are asymptomatic and detected incidentally on neuroimaging. The most common presentation is a seizure or slowly progressive focal neurology. Visual or hearing abnormalities may be present, depending on the site. Frontal tumours cause changes in personality. A parasagittal (falx) meningioma causes a characteristic pattern of bilateral leg weakness mimicking a spinal cord lesion. Spinal meningiomas cause limb weakness and numbness.

Investigations

CT or MRI scans show an enhancing tumour adjacent to dural structures. There may be areas of calcification. Angiography may be used for surgical planning, which shows a delayed ‘vascular blush’ due to arterial supply from the meninges.

Macroscopy/microscopy

Meningiomas are rounded, rubbery lesions, composed of meningothelial cells with small foci of calcification (psammoma bodies).

Prognosis

Depends on histological features.

The vast majority are typical (WHO grade 1) menin-giomas, which are slow growing and have a low risk of recurrence after surgical removal.

A small proportion are atypical (WHO grade 2–3) meningiomas with increased mitoses, nuclear pleomorphism and focal necrosis. These have a higher rate of recurrence.

There is a rare group of malignant (WHO grade 4) meningiomas which are locally invasive and may metastasise.