Historically, these fluid-filled bodies appeared on 1-4% of magnetic resonance imaging (MRI) brain scans, but were more frequently diagnosed at death, seen in 4-11% of autopsies.

[1] A 2007 study by Pu et al. found a frequency of 23% in brain scans (with a mean diameter of 4.3 mm).

The National Organization for Rare Disorders states that pineal cysts larger than 5.0 mm are "rare findings" and are possibly symptomatic.

If narrowing of the cerebral aqueduct occurs, many neurological symptoms may exist, including headaches, vertigo, nausea, muscle fasciculations, eye sensitivity, and ataxia.

[2] Pineal gland cysts typically require treatment only if they are symptomatic.