Fetus in fetu

الملخص EN

The fetus in fetu (FIF) is statement which is used to describe one of the asymmetrical monozygotic twinning.

In this kind of twinning, which is also called endoparasitic, one of the fetuses grows like a parasite inside the other one.

Endoparasitic twins are usually located in the upper abdominal retroperitoneum with close anastomosis to the vitellin circulation and it consists of vertebrae, dermal structures, extremities, intestine and neural tissues.

Less commonly they have gonads, adrenals, heart and lungs.

The sex ratio is equal.

Presented here is a case report from Iran.