A newborn baby was successfully operated on in the western Indian city of Mumbai after he was found to be 'pregnant' with his own twin.
Doctors believe it is a rare case of "foetus in foetu" – one of around 200 ever recorded. The 7cm mass – complete with a brain, arm and legs – was successfully removed from the baby's body.
Radiologist Dr Bhavna Thorat from Bilal Hospital, who first spotted the unusualness during a routine check-up of the mother, said: "It was inside a fetal sac of the newborn."
When the baby was born on 20 July, doctor immediately scanned him and found "another small child" inside it. "I could see bones of the upper and lower limbs of the fetus. The unique thing about it was I could see a tiny head with the brain inside," Dr Thorat said.
"However, this parasitic twin didn't have a skull bone," the doctor added, according to Zee News.
The baby boy was born in Bilal hospital, but was taken to another hospital named Titan for the surgery.
Dr Neena Nichlani, who performed the operation, said: "It is a case of monozygotic twin pregnancy sharing single placenta, where one fetus wraps itself around and envelops the other and robs the host of its nutrition."
"It can be implanted in [the] skull, abdomen or tail bone of the host. Sometimes it can also lead to the death of the host because both get nutrition from a single cord," Dr Nichlani said, adding that the baby and his 19-year-old mother both are doing well.
IBTimes UK contacted the Titan hospital and a staff member confirmed the news. The parents of the baby boy could not be contacted.
What is foetus in foetu?
Foetus in foetu is a rare medical condition in which a mass of tissue forms inside the hosts' body. The malformed and parasitic foetus resides inside the body of its host twin.
German anatomist Johann Friedrich Meckel described the condition in the late 18th century. Unlike the general notion at the time that the condition was the result of a highly developed teratoma – a tumour made up of out-of-place tissue, such as teeth and bone; Meckel believed that the growth was actually an underdeveloped twin.
Usually both the twins from parasitic pregnancies die before birth, but sometimes the parasitic twin remains inside its host for several years, Medical Daily reports.
According to the Embryo Project Encyclopedia, if the parasitic twin is removed on time, it does not create any problem for the host twin. Once it is removed from the host, regardless of their age, the host usually starts living a normal life.
One of the most widely covered cases of the condition is that of Sanju Bhagat. In 1999, Bhagat, then 36 years old, was rushed to Memorial Hospital in Mumbai after he complained of severe pain in his abdomen.
The doctor, who was expecting to remove a tumor from Bhagat's belly, found himself holding the hand of Bhagat's dead parasitic twin instead.
"To my surprise and horror, I could shake hands with somebody inside," Dr. Ajay Mehta told abc in an interview in 2006. "It was a bit shocking for me."
Another doctor recalled the extraordinary incident. "He just put his hand inside and he said there are a lot of bones inside," she said. "First, one limb came out, then another limb came out. Then some part of genitalia, then some part of hair, some limbs, jaws, limbs, hair."
In another incident, a 15-year-old Malaysian boy had his parasitic twin removed from his body in 2015.
The mother of the boy said she took her son to the hospital after he complained of pain in the stomach. After a successful surgery, doctors removed a foetus from his body. The parasitic twin had legs, hands and genitals; only "the nose and mouth were not complete", the 38-year-old mother had reportedly said.
In August 2016, a 15-month-old baby was operated on in India. According to reports, her stomach was so bloated that she could not eat or drink.
Scans found that she had an 8lb foetus in her body. Doctors successfully removed a mass of bone, flesh and hair from her body.