Thanks for writing in.
A bump on your head for a while, that is hard and firm might be a cyst arising from your scalp
. It may or may not be arising from the skull. If it has been present for a long time and is slowly growing, then it must be a benign lesion. In benign firm lesion, they can be osteoma
, epidermoid cyst
or dermoid cyst.
I would suggest you to consult a neurosurgeon and get a CT scan
done if necessary. Most likely it is not a brain tumor
and CT scan will tell if it needs to be removed.
Hope this helps.