In some people, like Liang Xiuzhen, such a horn even falls off and grows back, like a deer. The second horn then grew much faster.
These horns are actually made of horn, the same stuff our fingernails are made of: keratin.
Most of the time the horns are harmless, but there is often a fear that they could be tumors.
And in recent years, other elderly people from China have also made headlines with their own impressive growths.
(Wang, a Chinese farmer, the "human unicorn")
Why only Chinese people?
Human horns are not a new phenomenon. In 1930, Robert Ripley brought to the world's attention a Manchurian farmer named Wang, dubbed "The Human Unicorn." Wang's horn was 33 cm long and grew on the back of his head. Wang worked with a group of Chinese fakirs, and a tourist took a picture of him and sent it to Ripley.
Unfortunately, the photo was all Ripley would ever get. For years, Ripley offered a large reward to anyone who could track down Wang and bring him to America.
But the horned farmer proved to be as elusive as a real unicorn and was never to be found again.
(I don't know who this woman is)
Madame Dimanche, a 19th-century Parisian woman, began growing a thick horn on her forehead at the age of seventy. At first, the old woman didn't know what to make of the strange brown lump that appeared like an ash-colored patch in the middle of her head. But she knew she had to hide it, and she developed the habit of avoiding eye contact.
But the stump grew relentlessly, bigger and bigger, until it was as thick and dark as a branch." The horn reached over her face and eventually measured almost 20 cm in length.
Fortunately for Dimanche, an innovative French surgeon successfully removed it using an early form of plastic surgery.
A wax model of her face before the operation was acquired by Dr. Thomas Dent Mütter during a visit to Paris and can now be seen in the Mütter Museum of the College of Physicians of Philadelphia.
In 2010, a 101-year-old Chinese woman named Zhang became famous because two horns grew from her forehead. The first horn was almost 7 cm long, while the other had only just begun to grow.
I wouldn't have been particularly happy about such an "addition," but she was thrilled and wouldn't let them be removed.
Such horn growth generally begins with a mole, which eventually ruptures.
Many cases of human horns are documented in the 1894 book Anomalies and Curiosities of Medicine by Dr. George Gould and Dr. Walter Pyle.
( Horm in the ear )
They write
"Perhaps the most remarkable case of a horn was that of Paul Rodrigues, a Mexican doorman, who had a horn on the top and side of his head with a circumference of 14 inches, which was divided into three shafts and which he concealed by constantly wearing a peculiarly shaped red cap."
While most horns appear to occur on the head, Gould and Pyle also reported several cases of penis horns.
One of these very unfortunate men grew his horn at the age of 52. He had been circumcised four years earlier – which is painful and frightening enough – only to have a marble-sized horn grow at the surgical site.