Conversation: The conversation between human and AI assistant.
[|Human|] My 20 year old son has a hard lump about three inches up from tthe hair line at the back of the neck the size of small marble. Three years ago he had an xray and it showed it was bone nothing to worry about . This weekend he has worn a full face helmet which was tight and rubbed the lump. It looks a little bigger or swollen and he said tender .Today our doctor sent him for another xray just to check , But thinks its proberly the ill fitting helmet has cause it to swell slightly. Is this normal am a worried mum .
[|AI|]  Hello rearward welcome to Chat Doctor.come have evaluated your query thoroughly. Hope this clears your doubt . Wishing you fine recovery. Welcome for any further assistance. Regards take care. Hello rearward welcome to Chat Doctor.come have evaluated your query for your son in details .* The lump over back of scalp with this description seems to be sebaceous cyst most likely, needs confirmation with clinical examination. Hope this will help you for sure . Wishing him fine recovery. Welcome for any further guidance. Regards .