friends hairless rat grows tree bark

Question
Hello I have a friend with a approx. 1 yr old hairless rat, he has had a few rats before but this is his first hairless.  Today when I was visiting him I noticed his rat had a few very strange legions on it.  The first is maybe the size of a nickel, on the left side of the midsection, and looks like well tree bark or maybe the stuff that grows out of an old potato.  Somewhat scab-like but much stranger.  The second just an inch or so behind it was a lump but on top of the lump it appeared as if the lump was birthing this bark-like scab from the top of it.   I have been looking around the internet and haven't seen anything quite the same yet.  My friend doesn't have access to the internet an is an older man on a fixed income.    He said ever since his rat has become full grown he has had these growths, he has tried putting various ointments on it but the critter keeps licking it off so it really has no effect.  Im not sure what he has tried but can find out.  They don't seem to be painful to him nor is he lethargic or having appetite problems.  Do you have any idea of what this might be?  Oh he did tell me as well that his rat doesn't like baths too much he gave him a mini tub in his cage which he will stand in but fights and frights at being washed.  Could this be making matters worse?  And is this something that can be passed to humans or from them?  Thank you for any help and I can get some photos if I need to.  My friend says of all the rats he's had in the past this one is his favorite with the best personality and best temperament, its never even accidentally nipped him.  Oh and pardon me calling him just a rat the critters name escapes me at the moment.

Thank you so much,
Katie

Answer
I would need to see a photo but this sounds like either an infection or cancerous lesions.

Also keep in mind rats cannot pass things to humans other than ring worm, which ANY animal can pass. Everything else is species specific.   

Send photos to my email at sandyscrittercity @ Yahoo.com