If you're on Horse Vet Corner on Facebook you could post there and ask about it. You'll probably be told to have it biopsied, though. They might be able to tell you what treatments are okay for it topically, though, in the meantime. Or at least, which ones not to use.
I know the vets there seem to hate all the "kote" products, as the main active ingredient is alcohol which, according to their posts, kills healthy cells and impairs healing -- and also makes it impossible to suture if you use it on a fresh injury.