Doctors diagnosed it as a hemangioma – a collections of blood vessels that gather underneath the skin to form a reddish-purple lump.
Within seven months, the small mark swelled in size and became larger than her nose.
After specialist treatment the birthmark stopped growing, but it was still five times the size of her lip, which caused her difficulties talking, eating and smiling.
Fearing her daughter would be bullied, her mother, Hollianna Lockhart, 26, desperately looked for a surgeon to perform intricate surgery to reduce the mass.
Last week, Brianna, from Portsmouth, Ohio, was flown to Miami for the operation to remove the blood vessels and tissue in her mouth as well as reconstruct her lip.
Ms Lockhart, a call centre worker, said: ‘At its largest the hemangioma was the size of a kiwi and was so big that Brianna was struggling to eat and we had to feed her from an angle.
‘It was in front of where all of her teeth came in, so I’ve never seen her smile.
‘At one point it was bigger than her nose and poked out far past her nostrils.
‘Because it was so large, her speech was affected too, she couldn’t use the front of her mouth to make sounds and everything had to come from the back of her mouth.
‘I knew she needed surgery because of how hard it would be growing up and looking different from everyone else, I didn’t want her to be bullied or embarrassed by how she looked.
It takes between three and ten years for hemangiomas to reduce in size, according to the Vascular Birthmark Foundation (VBF), typically fading completely by adulthood.