Hi Bathsheba, welcome to able2know.
I don't have an answer for you, really. Maybe one of our vet. members will stop by your thread. I do have some experience with lumps-on-dogs.
My dog, a boxer, used to get lumps which were called mass or (mast?) cell tumors. They would pull cells (asperate) from the lump and rate the rate of growth is they found it to be cancerous. Hers were always slow-growing and I had them removed as she got them. She was always put under for the procedure.
She also had lumps which were fatty tissue. She had them removed while other tumors were being removed (at great expense
![Mad](https://cdn2.able2know.org/images/v5/emoticons/icon_mad.gif)
). The tumors ranged from what looked like a wart (her first one, on the surface of her skin) to a lump under the skin which was fairly uniform/round. I don't recall any difference in firmness between the two.
My sister's young pointer has a lump on her head. It's irregularly shaped and sometimes gets bigger and smaller. Their vet calls it scar tissue. It makes me nervous as it's so similar to my dog's lumps. But, the vet knows best.
The only real suggestion I can give you is to get a second opinion if it'll help you settle your nerves.