Cat has a boo-boo

[Moral Gutpunch]

I think my can has a bruise from mild fighting or playing too hard. It's small, but it shows through his white fur as slightly purple (at first I thought he sat on my pens again).

I can't get a good look as he freaks out every time I try to examine it, but he seems unconcerned otherwise.

Is this serious, or just something from roughhousing that'll go away?

[Shanna66]

If he freaks out whenever you try to mess with it i would go to the vet just to be on the safe side

[Flutter Fox]

Double check with a vet! Better safe then sorry.
Animals are very good at hiding pain and could be much worse then what you think.

[Aggressive_Stripper]

I would say take it to the vet just in case. It could be internal hemorrhaging or something of the like if it's worst case scenario.
Cats have been known to run around with broken backs so even if they seem fine, it may not be the case.