Hmmmmm Maybe? Hahha maybe you guys do XDI think they can get moles. Coming from someone who has randomly grows moles on my body, doctors thought I had skin cancer. Really, I'm just strange. Most of mine grow from places I've got cuts in the past. My cheek one grew randomly over time. The one near my eye and on my arm and leg and finger all came from places where I've taken a small chunk out of my skin. There is a story that everywhere you have a mole, is where you were stabbed in a past life! Anyway... Id take the rat to the vet incase it's cancer. Is the new growth on his tail too? If the rat is over all healthy, then maybe this rat and I somehow share blood from a past life!
Ya it kinda does, but it's a lot smaller than that.Is this kind of what it looks like? http://en.allexperts.com/q/Pet-Rats-3537/2011/5/Large-lump-tail.htm