I think it just happens like in humans.I had a bottle fed buck get a wart high on his hip that I thought that could have been from a dart.That was just my thought. I would tie dentil floss around it real tight about every 3 days.It grew to about 3 inches.It took about a month to strangle the blood supply and it finally fell off.
I think they are caused by biting insects or soil conditions in combination with a break in the skin that give the virus to the deer. I know they can spread from deer to deer. They should eventually go away on their own and not return. Maybe someone else can shed some more light on your question.
scott I did do it a little backwards after I posted it I looked it up and read the same thing on the site you recomended, thankyou everybody for your reply
My first breeder buck had a wart between his eyes on his forehead. It started as a pea and grew to a marble. Just when I started getting worried, it shrank and disappeared. Hope this is the case for you, too.