MRI scan; brain cancer (astrocytoma)

Magnetic resonance imaging scan showing cystic cerebellar astrocytoma. These are neoplasms of the brain and spinal cord derived from glial cells which vary from histologically benign forms to highly anaplastic and malignant tumors. Fibrillary astrocytomas are the most common type and may be classified in order of increasing malignancy (grades I through IV). In the first two decades of life, astrocytomas tend to originate in the cerebellar hemispheres; in adults, they most frequently arise in the cerebrum and frequently undergo malignant transformation. Tumours in this location frequently present with ataxia or signs of intracranial hypertension due to obstruction of the fourth ventricle.