A<unk>  is a cyst in the pineal gland, a small endocrine gland in the brain..  Statisically, these fluid-filled bodies appear on 1-4% of magnetic resonance imaging (MRI) brain scans.  They are more frequent at death, seen in 21-41% of autopsies, though researchers are not sure why.  They are in most cases asymptomatic, and it is rare for a pineal cyst to cause symptoms.  If they do, these would most likely be headache, visual disturbances, or hydrocephalus, which can be extremely dangerous if left untreated. Pineal cysts are not cancer and most of the time they do not enlarge over 2 centimeters.
Asymptomatic cysts require no treatment. Some doctors choose to monitor patients with CT scans or MRI to look for cyst growth, but most doctors do not.
Pineal gland cyst
Pineal gland tumor
Hidrocystoma
Epididymal head cyst
Scrotal cyst
Pilonidal cyst
Pineal embryonal carcinoma
Nabothian cyst