Updated

A four-year-old boy has become the smallest person in the UK to undergo a lung transplant, Sky News reported Wednesday.

Mason Lewis is just three feet tall and received lungs measuring only four inches long and weighing five ounces each. The organs were so small that surgeons at London's Great Ormond Street Hospital had to use amazingly delicate surgical techniques.

Mason, of Atherstone, Warwickshire, suffers from pulmonary hypertension, a rare blood vessel disorder of the lung, meaning he had to wear a backpack which continuously pumped drugs into his body in an attempt to keep open his blood vessels.

The only long-term treatment was a double lung transplant, which would normally only be done on children over 3-foot-3  tall.

Mom Rebecca said: "Mason will have to take anti-rejection drugs for the rest of his life, but he is able to take these orally and they are nothing like the continuous treatment he was on before."

Dr. Helen Spencer, consultant in transplant respiratory medicine, said: "We hope the fact we have been able to do this in someone as small as Mason will offer hope for patients like him in the future."

She added, "He has been incredibly lucky, not only to have a transplant, but to receive one so quickly."

The hospital would not say when the operation took place, to prevent the donor being identified.

Rebecca thanked the donor family. "They lost a child and have displayed courage and selflessness," she said.

Click here to read more on this story from Sky News.