Colloid cyst is a cyst containing gelatinous material in the brain. Colloid cysts are relatively rare intracranial lesions located in the rostral aspect of the third ventricle. They may produce acute hydrocephalus, brain herniation, and lead to death. These cysts account for approximately 1% of all intracranial tumors. Symptoms can include headache, vertigo, memory deficits, diplopia and behavioral disturbances. Other symptoms are associated with signs of increased intracranial pressure (eg, papilledema, emesis). Additionally, symptoms similar to normal pressure hydrocephalus have been associated with the presentation of colloid cysts.

The developmental origin is unclear, though they may be of endodermal origin, which would explain the mucin-producing, ciliated cell type. Colloid cysts account for 0.3% to 2% of all brain tumors. Presenting symptoms are usually related to impaired flow of cerebrospinal fluid. Symptomatic cysts vary from 6 mm to 9 cm in diameter. Hydrocephalus is the increased accumulation of cerebrospinal fluid within the ventricles of the brain. Colloid cysts enlarge by increased secretion of mucinous fluid from their epithelial cell wall lining. Cyst cavities may be filled with blood degradation products such as cholesterol crystals.

Colloid cysts normally originate in the anterior part of the third ventricle between the fornices. The cysts are attached to the roof of the third ventricle and often to the choroid plexus. Usually, the cysts are instantly dorsal to the foramen of Monro. These cysts have too been reported to often originate in the septum pellucidum, the fourth ventricle, and the sella turcica. Medical handling of these lesions is not proper nor indicated if the patient is symptomatic. Surgery is frequently indicated for these lesions and should be performed in a timely style. The goals are to alleviate hydrocephalus and to withdraw the danger of worsening in clinical position.