How To Treat Raised Circular Blob On Top Of Middle Finger?

I have a circular abrasion on the top of my middle finger = I have had it for about 2 years. I am a gardener and think it originated when gardening. It started as a depression but has gradually filled in = it is now a rather shiny scar like blob with raised sides and where it smooths out to the normal finger has a red ring around it. It is sore, sometimes painful if I catch it on the side and not pretty. I originally treated it as a wart which had no effect. Any ideas what it might be and how to get rid of it.