Growth on rats tail

Question
I just noticed my year and one month old female rat Roobee has a red/pinkish scab or growth on her tail.  Not sure what it is and couldn't find anything on it online.  It's about half the size of a pencil eraser.  I took a wet clothe and gently rub it on top of the growth to see if it was something just stuck on there and it didn't move, but didn't seem to bother Roobee at all, no flinch, no squeal, nothing.  It looks like it could have small white flecks on the top of it, but not positive on that.  If you could give me any information on what it could be, I would really appreciate it.  If you need or would prefer a picture, please let me know and I'll see if I can take one that shows enough detail lol.  Thanks so much for your time and expertise.

Amber

Answer
I do need a picture so I can get a better idea. I have had many people come to me with questions on stuff like this, some were very deep ulcerations that needed the tail to be amputated, others were simple abscesses that cleared up quickly.  You can attach one photo after each question or send to Sandyscrittercity@yahoo.com