A five-year-old boy is having to 'sit and wait' while a life-threatening lump grows on his brain.
Harvey Hawkins has developed a rare tumour on his brain called a colloid cyst. It is a 'ticking time bomb' that could cause severe brain damage or sudden death.
But the 9mm non-cancerous cyst cannot be removed until it has grown large enough for neurosurgeons to access it more easily.
Harvey's parents, Anita and Neil, from Milton Keynes, have spoken about the agonising wait ahead of them:
"If you saw him you wouldn't think there is anything wrong with him. He's a normal happy little boy but with a ticking time bomb in his brain," said Anita, 37.
"We just have to wait for the worst to come and then it is a matter of time whether we can save him. It could be tomorrow or it could be in 20 years, but once it grows too big it can cause sudden death."
"It's very hard to live with but we will try our utmost to save him when it comes to the worst."
Harvey began showing symptoms just before Christmas last year when he had an intense bout of vomiting, which doctors initially said may have been caused by gastoenteritis.
But when Harvey was still suffering from vomiting two days later, Anita took him back to the doctor and he was admitted to hospital for tests.
Harvey was sent home after five days and it seemed he was on the mend, until the symptoms returned on Boxing Day.
He then underwent an MRI scan at John Radcliffe Hospital in Oxford, which showed that he had a colloid cyst on the third ventricle of his brain - a location which makes operating on the cyst more dangerous.
Surgeons analysed the amount of pressure the cyst was placing on Harvey's brain and decided that operating on it would be more risky than waiting until it became larger - and easier to reach.
The danger is, if the cyst becomes too large it could stop vital fluids from reaching Harvey's brain, and raise the pressure within his skull, which could leave him brain damaged, or even kill him, if it's not removed in time.
Surgeons are currently keeping a close eye on Harvey and his family have to rush him to hospital if there are any changes to his condition.
"If his temperature goes above 37 degrees, or he has weakness in his limbs we have to act fast," said Anita.
"I had a call from his school that he was complaining his eyes were hurting, we spent three hours in A&E and it turned out he was just tired - but we can't take any chances.
"They call it a 'sit and wait' condition as there is nothing we can do. We try to put it to the back of our minds and to live a normal life, but this is reality."