Five year-old Wang Xingao desperately needs surgery to remove the growth or is facing a premature death.
The swelling appeared last year as a pimple-sized lump but has grown so large it leaves the little boy in permanent pain.
Now his family - who are poor farmers from Guannan county, in east China's Jiangsu province – have appealed for help after being turned away by dozens of hospitals because of the cost.
Wang Xingao's granddad, Liu Jun, said: "It was just a pimple when it appeared and then when it got to be the size of a small egg we tried to get help.
"I and my daughter, the boy's mother, went to a great many hospitals but it was all completely in vain. All we could do as we went from hospital to hospital was watch it getting bigger and now it is as big as his head.
"It weighs so much it is pushing his head to one side and now we are at the point where he is in a lot of pain. It is not even possible for him to see out of one eye any longer."
The frail old man has taken to begging at subway stations to try to raise the money his grandson needs.
Hospital officials have confirmed that without urgent treatment - which has to be paid for by the family - the boy will not live much longer.
A hospital spokesman said: "Even with treatment it will be very difficult to do anything because any cancer in the head is extremely hard to tackle – especially one as advanced as this."
Journalismwithoutborders.com has agreed to help raise funds and is in contact with the family about helping to get the operation organised as soon as possible.
Spokesman David Rogers said: "Our staff in China have spoken to the family and we will do all we can to raise some of the money so that the medical treatment can at least begin. Every day now is crucial."
If you would like to donate money in the hope of giving Wang Xingao a better future, click here.