MRI scan; brain cancer (meningioma)

Magnetic resonance image (MRI), axial slice, showing meningioma. This is a relatively common neoplasm of the central nervous system that arises from arachnoidal cells. The majority are well differentiated vascular tumours which grow slowly and have a low potential to be invasive, although malignant subtypes occur. Meningiomas have a predilection to arise from the parasagittal region, cerebral convexity, sphenoidal ridge, olfactory groove, and spinal canal. They tend to present in the fourth to sixth decades of life with signs indicative of a slowly progressive mass lesion. Specific clinical manifestations depend on the location of the tumour, but may include intracranial hypertension, cranial neuropathies, ataxia, and other focal neurologic signs.