You need to contact Dr. Rudolph Schrot at UC Davis in Sacremnto California, he's the expert on the west coast. I had a 6cm removed now have 3 in sacrum and 9 thoracic. If you have any questions I can help been down this road. A cyst that large can leak and or burst. Not trying to scare you just want you to understand this is the largest I've ever heard of. I have been living Tarlov Cyst for 10 plus years since my first large one was found. Most neuro surgeons will not touch or operate. Dr. Schrot will.. Nancy