OP...Oh thank goodness!! I am so glad.

I kept checking back on here hoping you would give us an update.
Thank you for doing so and I am so glad your cat is okay!

I'm glad it was just that

OP -- turns out it was a fatty deposit, can't remember what they are called. They're going to do a biopsy just to be sure but the vet seemed pretty confident from looking at it.

I don't know--my cats had internal tumors that were cancerous and there was nothing to be done by the time they were sick, so maybe it's a good sign that it's external and caught early!

Could be a fatty tumor. Hopefully whatever it is, it is benign. Good luck

Biopsy tomorrow and obviously we're concerned. This is an 8 year-old indoor cat who hasn't been vaccinated (because he stays indoors). Its on his back, hard and lumpy, maybe an inch, inch and a half. He is a fat cat.

Any thoughts on what it might, other than cancer? Likelihood of cancer? Can a fatty tumor feel hard?

Ack!