A woman in China's eastern Jiangxi province cut off her son's penis to "get back at her husband's family", Chinese media reported.
The boy, identified by Chinese news website Sina.com as Xiao Wen, is no longer in a critical condition.
The incident took place in Chongren county, in Jiangxi's Fuzhou city.
Xiao Wen was taken to hospital by his grandparents, with his trousers soaked in blood.
Doctors performed a phalloplasty or penis construction surgery, and his condition has stabilised, Sina.com reported on Wednesday (Aug 23).
Doctors said he will likely experience some difficulties in penile functions. However, he may still be able to have children in future, if he recovers well, they added.
The boy's paternal grandmother told Chinese media that the woman had left the family over a year ago, and married someone else.
The motives behind her actions are unclear.
Netizens expressed outrage, with many of them blasting the mother for "being sick".
One person wrote: "If you have any grudges, go look for the adults. Why do you hurt your own son?"
Police investigations are ongoing.