Often found in the front of the third ventricle of the brain and behind the opening at the base of the skull, a colloid cyst contains a thick fluid and is lined with epithelial cells. These types of cyst can be either very small or very large and are present at birth, with symptoms and signs developing later in life.

Thought to be a leftover piece of structure from the embryonic stage of fetal development, a colloid cyst is formed during brain development and is relatively rare. The smaller versions of the cysts don’t cause symptoms at all, whereas larger ones can lead to headaches and a blockage of cerebrospinal fluid, which can then accumulate dangerously in the brain and spinal cord and cause signs of hydrocephalus including nausea, vomiting, memory loss and coordination problems.

Colloid cysts are diagnosed through imaging (usually a CT scan) which gives its exact location and size and dictates the course of treatment. Surgery is the normal course of action as it is the fastest way to eliminate the cyst and prevent the dangerous results of hydrocephalus resulting from an abnormal build up and lack of circulation of cerebrospinal fluid. Recovery from surgery to remove a colloid cyst is typically quick, and most long-term prognoses are excellent.