Welcome to Yorkie Talk. Sorry your boy has a lump on his head. Since it is growing, it is best to have it surgically removed and biopsied to make sure it is benign.
How old is your boy? You could combine the lumpectomy with a dental cleaning while he is under.
Anesthesia is my least favorite thing to subject my boys to, but it is sometimes necessary. The risk is minimized with pre-op blood work and the proper anesthesia protocol:
http://www.yorkietalk.com/forums/yor...-protocol.html