Just with my experience of polyps, but in the sinuses not gallbladder.
Short story, they can turn nasty (again I am only refering to my polyps in my sinuses). Mine turned cancerous and grew up around my optic nerve and they were everywhere, so dr said 'I had to take your face off' to get them all. Right through both side sinuses growing wild. Took a bit of the nose but didn't take the jaw he said. Evidently they cut, send to pathology, get results and if the margin between the cancer cells and good skin is OK, they stop cutting but if not they keep going until there is a clear margin. Great specialist and no troubles (except no sinuses and a golf ball hole sized cut in my head).
So that was the very bad news, but, of late I visited Dr for prostrate and he said (amoung other things) I have many sists on my kidneys, but not to worry as that is quite normal for oldish people.
So for me the trick is to see 2 or 3 top notch specialist and go with the opinion you think.
Clarifying: see one dr and he says you have many sists/polyps etc, take out the organ and another specialist says, don't worry.