Cerebellar glioma (brain tumour). Magnetic resonance image (MRI) of a sagittal section of the brain of a man aged 40 years suffering from a cerebellar glioma, a brain tumour. The tumour appears in bright contrast to the surrounding brain tissue. The general term glioma encompasses tumours of variable malignancy derived from astrocytic origins, that is, from the framework of cells which support the nerve cells. Astrocytomas of the cerebellum, the part of the brain involved in co-ordination & balance, are often benign & very slow growing. They are generally cystic in form.