A Chinese toddler with an exceptionally large skull made history after becoming the first person in the world to successfully receive skull transplant surgery.

The 3-year-old baby, Han Han, had a peculiar medical condition known as hydrocephalus – a rare, excessive accumulation of a bodily fluid in the head. Due to the huge pressure inside her head, her skull was four times the size of a normal skull.

Chinese state media People’s Daily reported that the body fluid accounted for 85 percent of all the space inside her skull. The circumference of her head reached 85cm, which was significantly higher than the normal adult size of 50cm.

Before the surgery, her head weighed almost half of her total body weight.

Her vision also worsened significantly due to the worsening deformation – the sight in her right eye had already been lost.

Han Han also faced the possibility of death as her thinning skull made her vulnerable to infection.

Doctors estimated that the cost of the transplant surgery could range from RMB400,000 – RMB500,000. Her family were unable to afford the huge medical expense and had to rely on donations to save the toddler. The surgery was carried out in Hunan province on July 15.

During the operation, surgeons drained away a large volume of liquid. Her original skull was removed and replaced with a new skull created with a 3D printer.

According to the US National Institute of Neurological Disorders and Stroke, it is estimated that one to two of every 1,000 babies are born with hydrocephalus – the same medical condition as Han Han’s.

Eric is currently a Bachelor of Journalism student at the University of Hong Kong. Eric has his finger on the pulse of Hong Kong events and politics. His work has been published on The Guardian, Reuters and ABC News (America).