It may very well be something that is easily treated, but a vet will never take that gamble without ruling out more serious conditions.

Please don't let the fact that a biopsy has been taken make you worry more. It's always better to be safe than sorry and something that is pretty standard where lumps and bumps are concerned

A vet will take a biopsy to be 100% sure of what the lump is and how best to proceed, both of my old dogs had biopsies on lumpos..my girl suffered with lipomas, after the first couple of removals we went down the watch/ wait route...my lad, he had a cyst in a hair follicle. Sometimes no further action will be needed and sometimes it may warrant removal with good margins, I hope all will be well

They removed a lump from my dog's mouth and did a biopsy once even though they were 99% sure it was just a benign tumor (it was). They do them because the possibility is there, even if it's minute, and it's better to know than not.