Hi, I am a 55-year-old woman, 158 cm, and 53 kilos. About 2 weeks ago, as i was scratching my head, i noticed that there was a concavity in central part of my skull about the size of a cola cap. The next day, I went for a check-up. After seeing my scan result, my doctor said it was nothing to be worried about. The point is that, unfortunately, he didn t know what could the reason be, and why it happened. I would really appreciate it if you could give me some information about such phenomenon. how it happens? why it happens? is it something to be worried about? and is there any treatment?