It looks like it could be an abscess that needs drained.
I bet your right! Maybe it got a injury at one time and now is like that.
Caleb,
I personally like these types of “ID discussion” posts, but just to give you a heads-up, something like the below is likely incoming from a moderator:
Should I flag my own topic so it’s deleted?
You COULD do that, or better yet, you could:
Is the new title better?
IMO it’s better than a “What is this?” type of ID request, but you could go even broader. For example, a discussion about wildlife that seems okay despite (what you would think would be) medical problems.
For example, a lot of marine mammals in the Arctic contain very high levels of heavy metals due to bioaccumulation, but they seem to be okay. Etc.
Thanks for the help!
To keep this thread alive for the moment, reptiles in particular (I’m looking at you, crocodilians) can suffer horrific injuries (legs bitten off, jaws ripped off, etc.) and keep “doing their thing” for years.
That’s crazy!
I think a completely ripped off jaw would lead to starvation
In this case, humans helped it out:
https://www.cnn.com/travel/alligator-half-jaw-gets-name-gatorland-florida/index.html
There’s a deer in my area that I’ve passed by a few times with a similar lump in its chest. I haven’t been able to get a photo but it definitely doesn’t seem normal.
Interesting
Seroma?
I wanted to “like” this because the idea of flagging one’s own content for moderation made me smile, but I didn’t want to imply that’s what you should actually do. 
Let’s just make this a discussion anyway. 
Never a deer, but I had a mourning dove once with a huge growth on its head. I don’t know if it was cancerous or benign. Saw it for several days and that was it, so I assume either something got it or the growth was temporary and went away. I’ve also had a pet hamster with a giant tumor. It lived a normal hamster life other than the giant ugly growth on its head.
Two animals with growths on their heads? Makes me wonder where you live…