Colloid cyst

A colloid cyst is a cyst containing gelatinous material in the brain. It is almost always found just posterior to the foramen of Monro in the anterior aspect of the third ventricle, originating from the roof of the ventricle. Because of its location, it can cause obstructive hydrocephalus and increased intracranial pressure. A Colloid cyst of the third ventricle accounts for 0.55 to 2 percent of all intracranial tumors, about one per 1000 in asymptomatic patients.