• The second most common primary brain tumour in adults (after
• Meningiomas are typically benign, extrinsic tumours of the central nervous system. They arise from the arachnoid cap cells of the meninges and are typically located next to the dura and cause symptoms by compression rather than invasion.
• They typically are located at the falx cerebri, superior sagittal sinus, convexity or skull base.
• Histology: Spindle cells in concentric whorls and calcified psammoma bodies
• Investigation is with CT (will show contrast enhancement) and MRI, and treatment will involve either observation, radiotherapy or surgical resection.

MRI showing the typical well-circumscribed appearance. A dural tail can be where the tumour 'connects' to the dura. It is seen in around 65% of meningiomas.

GBM

![Glioblastoma multiforme - CT showing a peripherally enhancing lesion within the left frontal lobe. Note the contrast to the more homogenous meningioma above.

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Glioblastoma multiforme - CT showing a peripherally enhancing lesion within the left frontal lobe. Note the contrast to the more homogenous meningioma above.

Meningioma

slow-growing, benign tumors comprising 15% of intracranial tumors;

they are most common in the elderly.

They originate from either dura mater or arachnoid and are sharply demarcated from brain tissue.

Meningiomas often incite an osteoblastic reaction in the overlying cranial bones. (hyperostosis of the clavarium on SXR)

Microscopically, the meningioma cells have a tendency to encircle one another, forming whorls and psammoma bodies. Clinically, they present as mass lesions; seizures may occur. The superior parasagittal surface of the frontal lobes is a favorite site of origin. This can often produce leg weakness, since the leg motor fibers that pass down through the internal capsule originate in parasagittal cortical regions.