2 of my dogs have lipomas.
one has a quite large on on one shoulder.
the other younger dog has a very large one on the front of her chest.
It looks just like a breast implant LOL a mono boob.
Vet said to keep an eye on it but it grew quite fast as she gained weight, now it's too big to remove per vet.

I would have your dr look at them just to note the size and verify, if dr hasn't noticed them before.