I never do these things but my cat is having surgery today that will more than likely lead to his tail being amputated.
One of my cats, Jinx, has had a lump right near the base of his tail for quite a while. It was small and didn't hurt or bother him. It started growing earlier this year and we took him to the vet and they did 2 aspirations both of which were mostly inconclusive (the second came back as possibly nothing possibly cancer).
Since then, 2 months, it's been growing like crazy and has ulcerated now (likely from him licking/biting at it). It definitely is painful to the touch for him now and is bothering him.
He has surgery scheduled for this morning to have the lump removed. The vet told us that due to the size and placement there is pretty much no way that there will be enough skin to cover the wound area and he'll have to have his tail completely amputated. They'll do testing on the lump to finally determine exactly what it is. Hopefully it's not cancerous, but if it is hopefully it hasn't spread... I'm really worried for him. I really hope they are able to keep his tail. Since the lump is at the base of his tail he wouldn't even have a nub left really.
Please keep him in your thoughts & prayers today ladies.