I have had exactly the same thing in one of my emperors. Mine was a female, and also had a strange bulge on one side of the 4 and 5th mesosomal segment. Mine died after 8 months. I think this is a sign of sickness, probably an internal parasite or something, I am not sure what it was, but I suspect it to be the cause of death of my scorp, back then.
I also think it is not well. I can't say what it is but if you just bought it, take it back. If not give it the best existence until it dies, then dissect it to see what really was the problem. (I'm not being mean just logical)
I've seen a scorp in a pet store with a similar 'wound' the shop keeper said that something dropped on it while maintaining the enclosure. I've also heard tell of blockage in the digestive system 'impaction' that will cause a similar bulge. Parasites also have been tossed around as causes for that effect. 'You' can't say with a certainty until 'You' look inside.
It will die, so your best bet is trying to return it. (Preferably get your money back because if theres one bad one, they're might be more.) If this has been in your possesion for a while, I'd suggest just thoroughally examining your setup(s), make sure theres nothing in there thats not supposed to be. If you pruchased it recently that way, it serves as a small reminder to examine things before your purchase them. Either way it's not the end of the world. You just need to save 8 to 15 bucks for a new one, put on an old hat, ripped shirt and jeans and go sit on a busy street sidewalk, you'll be back in business in no time.