Giant arachnoid cyst associated with acute subdural haematoma: A case report.

Arachnoid cysts are extra-cerebral, intra-arachnoidal cerebrospinal fluid collections - the most frequent congenital developmental intracranial cystic lesions. They are often diagnosed incidentally during imaging exams acquired for different reasons, and are usually asymptomatic. Rare complications are post-traumatic rupture with consequent subdural haematomas. Spontaneous bleeding should be acknowledged as a rare but possible complication of this benign lesion. We report on the case of a patient presenting with a giant arachnoid cyst extending to the left frontal, temporal and parietal lobes associated with acute subdural haematoma without history of trauma.