What Causes Pulsating Bump On Forehead?

I have had a bump on the top right hand side of my forehead for some years now, I never really took it serious. It doesn't hut at all even if I push on it. When i put my fingers on it I can feel my pulse. Could this be something dangerous ? I don't seem to have had any side effects since I got it. If i remembered correctly, I got it when I ran into a pose. It started out as a hard pimple under my skin which would itch. It no longer itches tho there is still some pimples around it.I know it is wise to go and check it but can you give me an idea on what it might be ?