Help, what is this on my purple tang?!

[Biff0rz]

Hey everyone, I'm not sure what this is. This just showed up tonight, nothing added to the tank for a long while. I do have 3 long spine urchins in the tank. Did he get stung by one? He's eating, swimming, etc just fine.

Note, any specs other than the white blotch are just particles in the water from feeding.

 

[fishguy242]

Hi,looks like surface wound/scrape, at this point would watch close, should heal itself ,pretty quick,
anything worsens ,come back here asap ,we can get you some expert help.