[DMB FAN2]

I am not sure if this is the right forum- but here it goes! My friend was just dx with a subarachnoid cyst- which is very large- 9cm x 6cm x 4cm- and he has to see the neurologist yet- but I was wondering if this is something that needs to be surgically removed d/t the size- or if it can be left as is for now? Do these cysts have a certain etiology? I am scared for him- as a hospice nurse I deal with the worst outcomes.....I really need some info on this....and I knew that you all would come through for me.....any and all advice would be appreciated Thanks!