Fatty tumor is a term meaning NOT cancer cell tumor.

My dog developed one where the vet had given a vaccination, down her back and on her side, I remember the shot because it was not in the usual place.

Within 6 months a lump formed, he tested and found fat. The dog was not overweight by any means.

I have read that they can be 'drained', but it may take several times before they stop coming back, or they may keep coming back forever.