If you harvest him, I would visit with my local game biologist to make sure no CWD is involved there! Probably not, but I would not use for consumption there! Ive seen growths under the skin of some deer over the decades I been hunting, but nothing like that.
Mother Nature is gruel at times, and this is product we see!
I agree with stxranchman, these are fibromas. They are caused by a virus, are harmless to the deer and will go away. I know they look rough and I'm not sure about their affect on the meat but they are of now permanent harm to a whitetail. This one looks particularly odd because his rack is rather inferior.
"The world is littered with the bodies of people that tried to stick it to ole J.R."