<s>[INST] Hi. I am a female age 17. I have a large expanding indentation on the top back center of my skull . It was not there since I was born and I noticed it there when I was 14 years old. It is slightly more sensitive than the normal parts of my skull. I do have headaches every now and then but nothing out of the ordinary. Although occasionally it does feel bruised but that pain goes away with in a few days. Could you tell me what could have caused the indentation? And explain to me what it is precisely in detail? [/INST] Hi, Welcome to Chat Doctor forum.  It appears to be the swelling of the scalp skin, with an indentation of the skin in the center.  As it is not there since birth it is not a congenital problem. No pressure symptoms of the brain, so it has no relation with the intro cranial things.  So I advise you to consult a surgeon for diagnosis and treatment.  Wishing for a quick and complete recovery. Thank you. </s>