Hello Becky--I have a Posterior Fossa Arachnoid cyst about the size of a golf ball. It seems that I have had it for many years--maybe since birth. I am 49yrs old. As of right now the surgeon has not opted to do surgery on me. They are so successful in treating these cysts, and I am sure you are seeing a surgeon who specializes in this condition---and it is always good to get a second opinion also?? How old are you and what are your symtoms?? I wish you all the best----hutch