There are a lot of things it could be. If they did an aspirate of it, they probably would have been able to diagnose a lipoma (fatty cyst) then. Maybe it was inconclusive? Maybe there was something there that concerned the vet? Maybe it was in a bad location and the vet was worried about it growing and causing other problems by being in the way?
Even if it's not a lipoma, there are a lot of things that are equally benign that it could be. And if it's something less benign, taking it off is the best thing to do! So either way, you're doing the right thing for her. I hope the lab results come back quickly and you can know what your'e dealing with or set your mind at ease.
Rory actually has a little lipoma! Usually older dogs get them, but he's onoly 19 mo and Shelby's not much older!
Will be thinking good thoughts for you and your baby!
Dogs are not our whole life, but they make our lives whole.