A rare form of cancer, which induces rapid growth, makes 10 year old, Declan Gray, look like a teenager.
The tumor that grew in his chest caused him to show almost puberty type symptoms.
"Over a few months Declan suddenly shot up in size and we noticed he had body hair. It was heartbreaking for him because he knew he was different from other boys his age. He'd come home from school upset, because they'd been making fun of the size of his feet and he didn't want to get involved in school assemblies because he had a deep voice and everyone else's was still squeaky. He was also getting spots and blackheads just like a teenager," the Daily Express quoted his mum Linda, as saying.
She added: "It was obvious something was wrong. When I hugged Declan it was like holding a young man. He didn't have any facial hair but in terms of size and looks he was more like a 14 year old."
Tests showed high testosterone levels in Declan's blood, although, the source could not be identified. Then a scan last summer diagnosed a tumor on his chest that was surgically removed.
Further tests showed that it was a rare malignant germ cell tumor, which developed in less than 50 children in the UK every year. What causes the tumor is not clear, but they generally develop in the testicles and sometimes in the ovaries, but can also form in other parts of the body.
Linda recalled: "I broke down in tears...We had no warning it might be cancer. Apart from the symptoms of puberty there was no sign that Declan was ill."
Thereafter, Declan took chemotherapy sessions for six months at the Royal Manchester Children's Hospital
Linda says: "He was most scared about losing his hair. Every morning he'd tug at it. One day it just started coming out in clumps."
The treatment was successful and Declan returned to school. His mother says: "I always say it's like having two Declans.... One is a 10 year old and the other can be a moody teenager because the tumor also left him with some of the behavioral traits of a 14 year old."
She added: "I do feel symptoms of the tumor have cheated Declan out of part of his childhood. It's easy to forget he's only just 10. He doesn't know his own strength, which can cause problems when he's playing with other children - he sends the other lads flying. We've tried to explain to his school but he's often getting told off and he feels it's very unfair when he's punished."
Declan's parents also visited his school to speak to other children about their son's condition. He was often mocked at school for his size and even older boys bullied him, but all of it stopped after his parents spoke at school.
The 5ft 7in tall Declan will go through puberty again at the normal time but he might grow further.
Linda reveals: "We've been told to expect him to reach at least six foot."
Declan was nominated for a Cancer Research UK/TK Maxx Little Star Award, which are given to the under-17s who have cancer or have been treated for it in the last five years