Raised bumps in the center of both of my thumbs?

Both of my thumbs, on the pad side, have a raised bump in the center of them. When I look at my thumb from above, it looks like there is some kind of tiny soft ball underneath the skin which is causing the raised area but if I press on them I can't feel anything in there. If I slowly run my finger across them, while it's travelling the bump disappears and my thumb looks flat, but after I lift it off again the bump reappears. So I don't know what's causing them to be raised but the fact I have it in both my thumbs in the exact same place is pretty weird. Any corrective surgery for this?