Retroclival arachnoid cyst presenting with haemorrhage: a brief report of a special case.

Retroclival arachnoid cysts are rarely reported. A 40-year-old woman had a sudden onset of occipitocervical pain. Magnetic resonance imaging (MRI) revealed a cystic mass lesion located in the retroclival region and complicated with intracystic haemorrhage. At operation, by a right lateral suboccipital approach, an old, intracystic haemorrhage was aspirated and the cyst wall removed totally. This report demonstrated the second case of retroclival cyst presenting with symptomatic spontaneous intracystic haemorrhage.