What Causes Lump On The Scalp?

Hello. I have had a bump on my scalp for about 16 years. It is hard like bone, 1 inch wide, no discoloration, my skin covers it and there is no pain. I have never had this looked at by a doctor. I was just wondering if I should be concerned or if I should go have it examined, since it might just be a bone growth, or something more severe. Thank you.