Colloid cysts i.e. cysts filled with gelatinous material, in the central nervous system often are found in the third ventricle. Due to their location, chronic or intermittent hydrocephalus can result. Case reports of sudden death due to acute obstructive hydrocephalus are in the literature. Colloid cysts are benign lesions that should be considered for neurosurgical resection. [from
NCI]