A Chinese girl with a rare medical problem has the appearance of a child - despite being 19-years-old.

Zeng Yushan was born in June 1994 in the township of Huzhu in Fushun County in south-western China's Sichuan Province.

At seven years old, she stopped growing and was diagnosed with a tumour on her pituitary gland, which caused a deficiency in growth hormones.

Zeng Yushan, 19 (left), has the appearance of a seven-year-old as she stopped growing at this age due to a rare tumour on her pituitary gland. This gland releases growth and puberty hormones

Instead of going to school, Zeng was used as a child beggar due to her young appearance. After her father died in 2013, leaving her alone, she was taken in by a couple who have taken her to the doctor. They hope to take her to a specialist soon to see if anything can be done about her condition

The pituitary gland is found behind the bridge of the nose and below the base of the brain, and is about the size of a pea.

It releases hormones growth and puberty hormones, among others, directly into the blood stream.

Tumours on the pituitary gland - though rare - can stop people growing and developing normally, said Ashley Grossman, professor of endocrinology at Oxford University.

He told MailOnline: 'If you've got a pituitary tumour, it can stop growth hormones being released.

'You end up like a Tom Thumb person that looks small but is perfectly formed.

'Without treatment this woman won't grow at all, but she would age normally.

'Some say such children may even live longer than expected but that is uncertain.

'But in China, treatment for pituitary problems is not routinely available unless you pay for it.

'Pituitary patients often don't get the help they need.'

This was the case for Zeng's parents, who couldn't afford to pay for treatment.

They argued bitterly about the disease before finally divorcing, leaving Zeng with her father Yul Wei, 43.

HOW DOES A PITUITARY TUMOUR STOP GROWTH? Ashley Grossman, professor of endocrinology at Oxford University, said of Zeng's condition: ‘If you’ve got a pituitary tumour, it can stop growth hormones being released. ‘You end up a tomb thumb person, that looks small but is perfectly formed. ‘Without treatment this woman won’t grow at all. This woman would age normally, some say such children may even live longer than expected but that is uncertain. The pituitary gland is a pea-sized gland found found behind the bridge of the nose and below the base of the brain ‘In China treatment for pituitary problems is not routinely available unless you pay for it. 'Pituitary patients often don’t get the help they need. ‘This wouldn’t happen in the West, as paediatricians would be vigilant towards it. Pituitary tumour in childhood are very uncommon. One in 1000 adults has one and they are less common in children, he said. Some have a gene defect or a faulty gene. He added: ‘Now we have artificial growth hormones, that can be injected once a day, to treat this condition. ‘If you lose growth hormones you lose other hormones and you don’t ever go through puberty so you can have side effects like losing hair. Advertisement

But shortly after the divorce, her father was also diagnosed as being seriously ill.

Unable to pay any of their bills, the pair ended up on the streets begging, travelling from their home to the cities of Zigong, Chengdu and Guiyang.

Instead of going to school, Zeng was used as a child beggar due to her young appearance.

In 2013, Zeng's father died from gastric cancer, leaving her alone.

After she was spotted begging, a warm-hearted couple who had two grown-up daughters of their own, agreed to take her in.

Guo Liu, 50, said that when they first saw her, he and his wife were unsure if she was a boy or girl because she had no hair, and had suffered horrific physical problems because of her medical condition.

She is now getting regular medical care and although she is 20, still looks as if she is seven or eight-years-old and has the mental ability of a child aged around five or six.

Mr Gui said: 'We plan to take her after the Spring Festival to a doctor in the capital Beijing who might be able to help her.

'For the moment she is okay with us, but we want to try and get into a position where she might be able to do something for herself when we are no longer able to look after her.'

Zeng has made it clear she is hugely attached to her new parents.

Her biggest wish is to be able to go to school, even though no schools at the moment will take her because of her real age rather than her apparent age.

Commenting on the photographs and the story, Professor Grossman told MailOnline: 'This wouldn't happen in the West, as paediatricians would be vigilant towards it.

'Pituitary tumours in childhood are very uncommon. One in 1,000 adults has one and they are less common in children.

'Some have a gene defect or a faulty gene.

'We used to treat people with this condition with pituitaries from cadavers and dead people, but that led to complications.

'But luckily now we have artificial growth hormones, that can be injected once a day.

'If you lose growth hormones you lose other hormones and you don't ever go through puberty, so you can have side effects like losing hair.

He added that any treatment administered now to help her grow may not be successful.

He said: 'Whether anything can be done for her now is unclear. It depends on her bone age.

'I assume she didn't go through puberty so she didn't make sex hormones.

'In that case her bones will have fused.

'If the bones have an age of 8 or 9, she could respond to treatment, if she has bones that have an age of 14, she probably won't grow anymore.

'It would certainly be worth trying.

'She'll have to be investigated for all the other hormones the pituitary gland makes too.'