CASE HISTORY / CLINIC:
54-year-old patient with headache after a head injury.


FINDINGS:
Unenhanced CT-scan (without contrast administration).
Well circumscribed, smooth-edged liquor-isodense mass lesion around the left sylvian fissure. Thin skull cap in this area.


DIAGNOSIS:
Arachnoid cyst. Cerebellar atrophy as secundary finding.