Doctors at a hospital in Vietnam were shocked to find a partially-formed foetus inside a two-month old male infant, reports Thanhnienews.com.
The little one was operated upon in September and underwent a two-hour surgery. One of the surgeons told the media that it was an extremely rare case and in medical terms known as foetus-in-fetu, and it happens when one twin is absorbed inside another one.
Foetus-in-fetu occurs in about one of every 500,000 live births, according to a report in a June 2000 issue of the US journal Paediatrics.
The child's parents took the infant to the hospital for a check-up as they were worried about his swollen belly. Initial investigation suggested a giant tumour in the baby's stomach.
However, it was only during surgery that the doctors realised that the 1kg tumour was a foetus, complete with legs, arms, spinal column, part of the liver, and intestine.