Bearing Your Own Twin

May 16, 2008 — -- Doctors in Greece Thursday removed from the belly of a 9-year-old girl what they believe was her embryonic twin absorbed into her abdomen when they were both in the womb.

Andreas Markou, head of the pediatric department at Larissa General Hospital in Athens, said the 2-inch-long embryo removed from the girl's belly was a fetus with a head, hair and eyes, but no brain or umbilical cord, according to The Associated Press.

It is phenomenon called "fetus in fetu," or baby within a baby, said Jay Grosfeld, a professor of pediatric surgery at Indiana University who has written about the "exceptionally rare" condition.

In the first month of pregnancy while developing in the womb, Grosfeld said, one twin "enters into the other through the umbilical cord where it assumes a parasitic position in regard to the host baby. After birth, it presents as an abdominal mass."

In the early days of development, the parasitic twin "goes through that still developing opening in the abdomen. [The embryo] never fully develops, but it is a partially developed fetus that has certain structures like an axial spine and the beginnings of organs," said Grosfeld. "The parasitic twin is neither a true twin nor a conjoined twin."

"This lump or mass palpates in belly," he said. "It appears in images as a calcified structure. You can see the bone structure and axial configuration of the spine."

Grosfeld said that once the mass is removed, children typically recover quickly with no longstanding damage.

"As far as the problems kids can have, it is not that bad," he said. "The child is usually otherwise perfectly healthy."

The girl, whose name has not been released publicly, is recovering well, according to the AP. ABC News could not reach the girl's doctors in Greece.

"[The doctors] could see on the right side that her belly was swollen, but they couldn't suspect that this tumor would hide an embryo," hospital director Iakovos Brouskelis told the AP.

Fetus in fetu is very rare, Grosfeld said. The Greek physicians said it occurred only once in every 500,000 people.