I was tempted to suggest your neuro did not mention it because he expected it would be a cause of increasing your anxiety. Your anxiety can be worse than the cyst.

It is not a foreign mass. It is just a sack of fluid that normally just drains or is absorbed by the body. Nationwide, less than 100 are symptomatic and require treatment each year. Historically, these fluid-filled bodies appeared on 1-4% of magnetic resonance imaging (MRI) brain scans, but are more frequent at death, seen in 21-41% of autopsies.

One of the problems with getting MRI's done, especially when there are no valid indicators for the MRI, is that benign things are often found. Benign means the condition has no negative health impact or is not spreading.

There are many imaging and diagnostic systems that if used frequently, would have lots of people seeking treatment for conditions that are not worthy of treating. Many MRI's are done just to alleviate anxiety and protect doctors from liability. Few are done for true medically necessary reasons.