Unusual presentation of fetus in fetu in triplet pregnancy mimicking abdominal wall defect

Fetus in fetu (FIF) is a rare form of twinning in which an immature twin develops parasitically inside the other twin. The most frequent location of a parasitic fetus is the retroperitoneal region. A FIF located on the abdominal wall is an unusual condition, and it should be kept in mind as one of the differential diagnoses of abdominal wall masses.