If you received Deer Tracking (Spring issue), pg 22-we had a "warty buck" update that explained the fibroma virus. Some think it may be spread by mosquitoes, generally hits yearlings, fibromas fall off by end of season and generally the deer don't get them again. Unless it looks like it will cause blocked vision, or a secondary infection is noticed, experts recommend leaving them run their course. This topic has been covered as "Ask The Experts" in different issues of the magazine with different pictures and explanations.
Hope that helps