Doctors find bizarre mass of bone, teeth & hair in teen's stomach... and it that of her ......

A teenager in India was discovered to have a bizarre mass of bone, teeth and "hairy cheesy material" in her abdomen, according to a new report of the case. 

It was her own "twin" growing inside her, the result of an extremely rare condition called "fetus in fetu."

The 17-year-old went to the doctor after developing a lump in her abdomen that had been gradually increasing in size over the last five years, according to the report, published Aug. 12 in the journal BMJ Case Reports. The teen told doctors that she sometimes experienced abdominal pain and a feeling of fullness, even when she had not eaten much food.

A CT scan revealed that the teen had a large mass in her abdomen that appeared to contain multiple bones "resembling the shape of vertebrae, ribs and long bones," the authors wrote.

 Doctors diagnosed the teen with fetus in fetu, a condition that is estimated to occur in only about 1 in 500,000 people worldwide.

The new case is even more unusual because it was diagnosed in a teenager, whereas most previous cases have been found in infancy or early childhood, the authors said. What's more, the mass appears to be the largest one ever discovered in a case like this, they said.

When doctors took it out, the mass was about two-thirds the size of a full-term baby: It measured 14 by 6 by 4 inches (36 by 16 by 10 centimeters) "and was composed of hairy cheesy material, multiple teeth and structures resembling limb buds". It also contained skin, hair and fat tissue, they said.