Thank you for posting your query.
It is uncommon for sutures to remain open till the age of 51. So, most likely, it is a case of partial closure.
It is not of much clinical significance and would not lead to any serious problems.
Pain on touching at that spot is probably due to hypersensitivity
of the nerves in the scalp
(skin over the skull bone).
You may benefit from neuropathic pain
medications such a pregabalin
Best wishes for a good health,
Dr Sudhir Kumar MD DM (Neurology)
Senior Consultant Neurologist
Apollo Hospitals, Hyderabad