There is an extra-axial hypodense lesion within the right cerebellar pontine angle, extending over the free edge of the right tentorial leaf and into the floor of the right middle cranial fossa. The lesion has no internal calcification or haemorrhagic foci. There is mass-effect upon the right middle cerebellar peduncle and midbrain which are displaced to the left. There is also minor effacement of the 4th ventricle without entrapment. No hydrocephalus. Normal grey-white matter differentiation is maintained with no CT evidence of acute infarction. There is extensive coarse dural calcification, predominantly along the falx and tentorium cerebelli, the cause of which is unclear.