The angry, ulcerated red growth not only left three-year-old Millie Field terribly disfigured but was also growing around her windpipe, jaw and larynx and choking her.
Now the toddler has become the first person in Britain to trial a miracle drug which shrunk the birthmark – and saved Millie's life.
The youngster was born with a small, blue mark on her face which doctors told her parents Michelle and Stuart was a bruise from a super-speedy 90 minute labour.
But a few days later the mark had developed and at the age of just three weeks Millie was taken into intensive care where she spent the next six months.
By this point the birthmark, known as a hemangioma, had grown so large that Millie needed a tracheostomy just to breathe.
The operation in June 2008 left her unable to make a sound. But now she can speak and smile just like a typical todder after her parents took a gamble on the new drug.
"Millie is a little fighter," her mum, Michelle, 37, from Rochford in Essex said.
"Right from the beginning she was not going to let this thing beat her and we are just so proud of everything she has had to overcome.
"The results of the drug were instant. We could see before our very eyes that the birthmark was changing colour and getting smaller over a period of days. Now she is doing remarkably well. It's completely changed her life.
"I am just so grateful for everything the doctors and nurses have done for us in allowing Millie to live a totally normal life, which at one point we feared would never be possible."
Michelle recalled the terror she felt as the birthmark took hold and she saw her daughter deteriorate.
"One of the saddest parts was not being able to feed her and look after her and never hearing her cry or make a sound," she said.
"The tumour was growing everywhere meaning she couldn't suck, swallow and breathe at the same time.
"It's hard to describe how we felt about everything because we barely had time to adjust to it. It all happened so fast. One minute we had our baby daughter and were imagining what she was going to do in the future and the next minute all those things felt like a pipe dream.
"Now she couldn't even breathe on her own."
Millie was admitted to hospital but her future seemed uncertain until one day Michelle heard about a new drug trial taking place in France. There doctors had seen some success in treating hemangiomas with a drug called propanolol, a beta-blocker used to treat hypertension and heart conditions.
Doctors noticed that when children with heart complaints who also had hemangiomas were treated with the drug that their tumours appeared to shrink. However, doctors were at first reluctant to take a risk, but Millie's parents insisted.
"She wasn't improving and had no quality of life - she was just getting worse and worse," her mum said.
Eventually the doctors relented and while under strict supervision Millie was given the drug from July 2008 to August 2010 in slowly increasing doses.
Miraculously, the birthmark which had blighted her young life began to fade before her parents' eyes.
Michelle said: "The result was almost instant. We could see it changing colour straightaway and developing clear patches on her face.
"It changed her life completely. The tumour was really sore and she never liked to be touched or picked up because it gave her so much pain. She needed morphine on a regular basis just to make her comfortable.
But now, we were able to kiss and cuddle her and within a few days she was able to move her head from side to side.
After a few failed attempts to remove Millie's tracheostomy, it was decided she would need to have her airway reconstructed using a piece of rib cartilage as the tumour had damaged it so severely.
So in April 2010 she underwent a complicated surgery to rebuild her airway and after two weeks in hospital was finally able to breathe on her own. In January Millie is due to have plastic surgery to reconstruct her lip although she will still have extensive scarring.
Michelle said: "She still has some speech problems because of the damage to her mouth, but her naso-gastric tube was taken out last October and since then she can basically do everything a normal three-year-old can do.
"I do sometimes worry about how people will react to her when she starts school as my instinct is to protect her. Sometimes even adults stare and say thoughtless things like, 'Oh, your daughter has chocolate on her face'.
"As far as I'm concerned she is beautiful and we are just glad she has been given the chance to live her life like any other little girl because at one time we weren't sure any of this would be possible."
• For more information about birthmarks, contact The Birthmark Support Group at www.birthmarksupportgroup.org.uk or by calling 0845 045 4700