How does one distinguish between an arachnoid cyst and a tumor? without contrast. how can one see if it is an arachnoid cyst and not another type of cyst or a cancerous cyst? also if arachnoid, how can one tell it is or isnt the cause of symptoms?

Neurologist: These questions are not relevant to most specialists in medicine, let alone a lay person. Your neurologist and neurosurgeon should be the ones to figure it out. Wish you good health!

Not difficult : Arachnoid cysts are usually chronic innocent collections of cerebrospinal fluid often discovered by chance that have no pressure effects and remain static in appearance when followed up !