A 19-year-old man has had part of his right breast removed after it grew to the size of an A cup.
According to The Sun UK, the young man from Cangnan County in China’s eastern Zhejiang Province, first noticed his single man boob growing when he was just 13.
The condition was put down to his body producing an excess of female hormones.
Known only by his nickname Xiao Feng, the teen sought help from doctors after his uneven chest became more obvious.
Last month he checked himself into Zhejiang’s Wenzhou Central Hospital.
Chief of Medicine Pan Zhongliang said: “The right side of the patient’s body resembles a woman, while the left – a man.”
He said that hormonal imbalances were very common in young adults, especially as they go through puberty.
Xiao had breast reduction surgery and was allowed home five days later.
Man boobs, or “moobs”, are caused by a medical condition called gynecomastia.
It can be caused by a hormone imbalance or a build up of fatty tissue around the breast area.
Generally, if it is hormonal, it begins during puberty and the tissue is more like fibrous breast tissue.
Men who have more female sex hormones than normal will develop breasts.
During puberty it is normal for a boys breasts to swell slightly.
As their body goes through puberty their hormones begin to change and they start to produce more testosterone, the male sex hormone.
But, men with gynecomastia tend to have less testosterone than oestrogen, the female sex hormone.
This can be caused by a natural hormone imbalance, medications, steroids and possibly underlying health problems like liver failure and cirrhosis, which causes hormonal fluctuations.
Luckily, there is a way for the condition to be fixed.
If the swelling doesn’t go down after a man has gone through puberty, plastic surgeons can excise the fibrous breast tissue to even out and flatten his chest.