A Case of Fetus in Fetu / 대한주산의학회잡지

Fetus in fetu is an extremely uncommon cause of abdominal mass in the neonate with an incidence of 1 in 500,000 births. This is thought to occur when a monozygotic, diamniotic twin is incorporated into the body of its sibling early in embryonic development. A case of retroperitoneal fetus in fetu in a 3 day old male infant is reported, the excised round mass contained the vertebral column, 2 feet, 2 arms, small penis and testis. The presence of vertebral axis and organogenesis differentiates it from a teratoma. More than 100 cases of fetus in fetu have been reported, most of which have been in the abdomen. We report a case of a well developed fetus in the retroperitoneal area of a neonate delivered at term.